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-DNSEXT D. Blacka
-Internet-Draft VeriSign, Inc.
-Intended status: Standards Track April 7, 2006
-Expires: October 9, 2006
-
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- DNSSEC Experiments
- draft-ietf-dnsext-dnssec-experiments-03
-
-Status of this Memo
-
- By submitting this Internet-Draft, each author represents that any
- applicable patent or other IPR claims of which he or she is aware
- have been or will be disclosed, and any of which he or she becomes
- aware will be disclosed, in accordance with Section 6 of BCP 79.
-
- Internet-Drafts are working documents of the Internet Engineering
- Task Force (IETF), its areas, and its working groups. Note that
- other groups may also distribute working documents as Internet-
- Drafts.
-
- Internet-Drafts are draft documents valid for a maximum of six months
- and may be updated, replaced, or obsoleted by other documents at any
- time. It is inappropriate to use Internet-Drafts as reference
- material or to cite them other than as "work in progress."
-
- The list of current Internet-Drafts can be accessed at
- http://www.ietf.org/ietf/1id-abstracts.txt.
-
- The list of Internet-Draft Shadow Directories can be accessed at
- http://www.ietf.org/shadow.html.
-
- This Internet-Draft will expire on October 9, 2006.
-
-Copyright Notice
-
- Copyright (C) The Internet Society (2006).
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-Blacka Expires October 9, 2006 [Page 1]
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-Internet-Draft DNSSEC Experiments April 2006
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-Abstract
-
- This document describes a methodology for deploying alternate, non-
- backwards-compatible, DNSSEC methodologies in an experimental fashion
- without disrupting the deployment of standard DNSSEC.
-
-
-Table of Contents
-
- 1. Definitions and Terminology . . . . . . . . . . . . . . . . . 3
- 2. Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
- 3. Experiments . . . . . . . . . . . . . . . . . . . . . . . . . 5
- 4. Method . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
- 5. Defining an Experiment . . . . . . . . . . . . . . . . . . . . 8
- 6. Considerations . . . . . . . . . . . . . . . . . . . . . . . . 9
- 7. Use in Non-Experiments . . . . . . . . . . . . . . . . . . . . 10
- 8. Security Considerations . . . . . . . . . . . . . . . . . . . 11
- 9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 12
- 10. References . . . . . . . . . . . . . . . . . . . . . . . . . . 13
- 10.1. Normative References . . . . . . . . . . . . . . . . . . 13
- 10.2. Informative References . . . . . . . . . . . . . . . . . 13
- Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 14
- Intellectual Property and Copyright Statements . . . . . . . . . . 15
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-1. Definitions and Terminology
-
- Throughout this document, familiarity with the DNS system (RFC 1035
- [5]) and the DNS security extensions ([2], [3], and [4] is assumed.
-
- The key words "MUST, "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
- "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY, and "OPTIONAL" in this
- document are to be interpreted as described in RFC 2119 [1].
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-2. Overview
-
- Historically, experimentation with DNSSEC alternatives has been a
- problematic endeavor. There has typically been a desire to both
- introduce non-backwards-compatible changes to DNSSEC and to try these
- changes on real zones in the public DNS. This creates a problem when
- the change to DNSSEC would make all or part of the zone using those
- changes appear bogus (bad) or otherwise broken to existing security-
- aware resolvers.
-
- This document describes a standard methodology for setting up DNSSEC
- experiments. This methodology addresses the issue of co-existence
- with standard DNSSEC and DNS by using unknown algorithm identifiers
- to hide the experimental DNSSEC protocol modifications from standard
- security-aware resolvers.
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-3. Experiments
-
- When discussing DNSSEC experiments, it is necessary to classify these
- experiments into two broad categories:
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- Backwards-Compatible: describes experimental changes that, while not
- strictly adhering to the DNSSEC standard, are nonetheless
- interoperable with clients and servers that do implement the
- DNSSEC standard.
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- Non-Backwards-Compatible: describes experiments that would cause a
- standard security-aware resolver to (incorrectly) determine that
- all or part of a zone is bogus, or to otherwise not interoperate
- with standard DNSSEC clients and servers.
-
- Not included in these terms are experiments with the core DNS
- protocol itself.
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- The methodology described in this document is not necessary for
- backwards-compatible experiments, although it certainly may be used
- if desired.
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-4. Method
-
- The core of the methodology is the use of strictly unknown algorithm
- identifiers when signing the experimental zone, and more importantly,
- having only unknown algorithm identifiers in the DS records for the
- delegation to the zone at the parent.
-
- This technique works because of the way DNSSEC-compliant validators
- are expected to work in the presence of a DS set with only unknown
- algorithm identifiers. From [4], Section 5.2:
-
- If the validator does not support any of the algorithms listed in
- an authenticated DS RRset, then the resolver has no supported
- authentication path leading from the parent to the child. The
- resolver should treat this case as it would the case of an
- authenticated NSEC RRset proving that no DS RRset exists, as
- described above.
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- And further:
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- If the resolver does not support any of the algorithms listed in
- an authenticated DS RRset, then the resolver will not be able to
- verify the authentication path to the child zone. In this case,
- the resolver SHOULD treat the child zone as if it were unsigned.
-
- While this behavior isn't strictly mandatory (as marked by MUST), it
- is likely that a validator would implement this behavior, or, more to
- the point, it would handle this situation in a safe way (see below
- (Section 6).)
-
- Because we are talking about experiments, it is RECOMMENDED that
- private algorithm numbers be used (see [3], appendix A.1.1. Note
- that secure handling of private algorithms requires special handing
- by the validator logic. See [6] for further details.) Normally,
- instead of actually inventing new signing algorithms, the recommended
- path is to create alternate algorithm identifiers that are aliases
- for the existing, known algorithms. While, strictly speaking, it is
- only necessary to create an alternate identifier for the mandatory
- algorithms, it is suggested that all optional defined algorithms be
- aliased as well.
-
- It is RECOMMENDED that for a particular DNSSEC experiment, a
- particular domain name base is chosen for all new algorithms, then
- the algorithm number (or name) is prepended to it. For example, for
- experiment A, the base name of "dnssec-experiment-a.example.com" is
- chosen. Then, aliases for algorithms 3 (DSA) and 5 (RSASHA1) are
- defined to be "3.dnssec-experiment-a.example.com" and
- "5.dnssec-experiment-a.example.com". However, any unique identifier
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- will suffice.
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- Using this method, resolvers (or, more specifically, DNSSEC
- validators) essentially indicate their ability to understand the
- DNSSEC experiment's semantics by understanding what the new algorithm
- identifiers signify.
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- This method creates two classes of security-aware servers and
- resolvers: servers and resolvers that are aware of the experiment
- (and thus recognize the experiment's algorithm identifiers and
- experimental semantics), and servers and resolvers that are unaware
- of the experiment.
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- This method also precludes any zone from being both in an experiment
- and in a classic DNSSEC island of security. That is, a zone is
- either in an experiment and only experimentally validatable, or it is
- not.
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-5. Defining an Experiment
-
- The DNSSEC experiment MUST define the particular set of (previously
- unknown) algorithm identifiers that identify the experiment, and
- define what each unknown algorithm identifier means. Typically,
- unless the experiment is actually experimenting with a new DNSSEC
- algorithm, this will be a mapping of private algorithm identifiers to
- existing, known algorithms.
-
- Normally the experiment will choose a DNS name as the algorithm
- identifier base. This DNS name SHOULD be under the control of the
- authors of the experiment. Then the experiment will define a mapping
- between known mandatory and optional algorithms into this private
- algorithm identifier space. Alternately, the experiment MAY use the
- OID private algorithm space instead (using algorithm number 254), or
- MAY choose non-private algorithm numbers, although this would require
- an IANA allocation.
-
- For example, an experiment might specify in its description the DNS
- name "dnssec-experiment-a.example.com" as the base name, and declare
- that "3.dnssec-experiment-a.example.com" is an alias of DNSSEC
- algorithm 3 (DSA), and that "5.dnssec-experiment-a.example.com" is an
- alias of DNSSEC algorithm 5 (RSASHA1).
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- Resolvers MUST only recognize the experiment's semantics when present
- in a zone signed by one or more of these algorithm identifiers. This
- is necessary to isolate the semantics of one experiment from any
- others that the resolver might understand.
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- In general, resolvers involved in the experiment are expected to
- understand both standard DNSSEC and the defined experimental DNSSEC
- protocol, although this isn't required.
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-6. Considerations
-
- There are a number of considerations with using this methodology.
-
- 1. Under some circumstances, it may be that the experiment will not
- be sufficiently masked by this technique and may cause resolution
- problem for resolvers not aware of the experiment. For instance,
- the resolver may look at a non-validatable response and conclude
- that the response is bogus, either due to local policy or
- implementation details. This is not expected to be a common
- case, however.
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- 2. It will not be possible for security-aware resolvers unaware of
- the experiment to build a chain of trust through an experimental
- zone.
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-7. Use in Non-Experiments
-
- This general methodology MAY be used for non-backwards compatible
- DNSSEC protocol changes that start out as or become standards. In
- this case:
-
- o The protocol change SHOULD use public IANA allocated algorithm
- identifiers instead of private algorithm identifiers. This will
- help identify the protocol change as a standard, rather than an
- experiment.
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- o Resolvers MAY recognize the protocol change in zones not signed
- (or not solely signed) using the new algorithm identifiers.
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-8. Security Considerations
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- Zones using this methodology will be considered insecure by all
- resolvers except those aware of the experiment. It is not generally
- possible to create a secure delegation from an experimental zone that
- will be followed by resolvers unaware of the experiment.
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-9. IANA Considerations
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- This document has no IANA actions.
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-10. References
-
-10.1. Normative References
-
- [1] Bradner, S., "Key words for use in RFCs to Indicate Requirement
- Levels", BCP 14, RFC 2119, March 1997.
-
- [2] Arends, R., Austein, R., Larson, M., Massey, D., and S. Rose,
- "DNS Security Introduction and Requirements", RFC 4033,
- March 2005.
-
- [3] Arends, R., Austein, R., Larson, M., Massey, D., and S. Rose,
- "Resource Records for the DNS Security Extensions", RFC 4034,
- March 2005.
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- [4] Arends, R., Austein, R., Larson, M., Massey, D., and S. Rose,
- "Protocol Modifications for the DNS Security Extensions",
- RFC 4035, March 2005.
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-10.2. Informative References
-
- [5] Mockapetris, P., "Domain names - implementation and
- specification", STD 13, RFC 1035, November 1987.
-
- [6] Austein, R. and S. Weiler, "Clarifications and Implementation
- Notes for DNSSECbis", draft-ietf-dnsext-dnssec-bis-updates-02
- (work in progress), January 2006.
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-Author's Address
-
- David Blacka
- VeriSign, Inc.
- 21355 Ridgetop Circle
- Dulles, VA 20166
- US
-
- Phone: +1 703 948 3200
- Email: davidb@verisign.com
- URI: http://www.verisignlabs.com
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-Full Copyright Statement
-
- Copyright (C) The Internet Society (2006).
-
- This document is subject to the rights, licenses and restrictions
- contained in BCP 78, and except as set forth therein, the authors
- retain all their rights.
-
- This document and the information contained herein are provided on an
- "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS
- OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND THE INTERNET
- ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED,
- INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE
- INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED
- WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
-
-
-Intellectual Property
-
- The IETF takes no position regarding the validity or scope of any
- Intellectual Property Rights or other rights that might be claimed to
- pertain to the implementation or use of the technology described in
- this document or the extent to which any license under such rights
- might or might not be available; nor does it represent that it has
- made any independent effort to identify any such rights. Information
- on the procedures with respect to rights in RFC documents can be
- found in BCP 78 and BCP 79.
-
- Copies of IPR disclosures made to the IETF Secretariat and any
- assurances of licenses to be made available, or the result of an
- attempt made to obtain a general license or permission for the use of
- such proprietary rights by implementers or users of this
- specification can be obtained from the IETF on-line IPR repository at
- http://www.ietf.org/ipr.
-
- The IETF invites any interested party to bring to its attention any
- copyrights, patents or patent applications, or other proprietary
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- this standard. Please address the information to the IETF at
- ietf-ipr@ietf.org.
-
-
-Acknowledgment
-
- Funding for the RFC Editor function is provided by the IETF
- Administrative Support Activity (IASA).
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-DNSEXT Working Group Bernard Aboba
-INTERNET-DRAFT Dave Thaler
-Category: Standards Track Levon Esibov
-<draft-ietf-dnsext-mdns-46.txt> Microsoft Corporation
-16 April 2006
-
- Linklocal Multicast Name Resolution (LLMNR)
-
-Status of this Memo
-
- By submitting this Internet-Draft, each author represents that any
- applicable patent or other IPR claims of which he or she is aware
- have been or will be disclosed, and any of which he or she becomes
- aware will be disclosed, in accordance with Section 6 of BCP 79.
-
- Internet-Drafts are working documents of the Internet Engineering
- Task Force (IETF), its areas, and its working groups. Note that
- other groups may also distribute working documents as Internet-
- Drafts.
-
- Internet-Drafts are draft documents valid for a maximum of six months
- and may be updated, replaced, or obsoleted by other documents at any
- time. It is inappropriate to use Internet-Drafts as reference
- material or to cite them other than as "work in progress."
-
- The list of current Internet-Drafts can be accessed at
- http://www.ietf.org/ietf/1id-abstracts.txt.
-
- The list of Internet-Draft Shadow Directories can be accessed at
- http://www.ietf.org/shadow.html.
-
- This Internet-Draft will expire on October 15, 2006.
-
-Copyright Notice
-
- Copyright (C) The Internet Society 2006.
-
-Abstract
-
- The goal of Link-Local Multicast Name Resolution (LLMNR) is to enable
- name resolution in scenarios in which conventional DNS name
- resolution is not possible. LLMNR supports all current and future
- DNS formats, types and classes, while operating on a separate port
- from DNS, and with a distinct resolver cache. Since LLMNR only
- operates on the local link, it cannot be considered a substitute for
- DNS.
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-Aboba, Thaler & Esibov Standards Track [Page 1]
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-INTERNET-DRAFT LLMNR 16 April 2006
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-Table of Contents
-
-1. Introduction .......................................... 3
- 1.1 Requirements .................................... 4
- 1.2 Terminology ..................................... 4
-2. Name Resolution Using LLMNR ........................... 4
- 2.1 LLMNR Packet Format ............................. 5
- 2.2 Sender Behavior ................................. 8
- 2.3 Responder Behavior .............................. 8
- 2.4 Unicast Queries and Responses ................... 11
- 2.5 Off-link Detection .............................. 11
- 2.6 Responder Responsibilities ...................... 12
- 2.7 Retransmission and Jitter ....................... 13
- 2.8 DNS TTL ......................................... 14
- 2.9 Use of the Authority and Additional Sections .... 14
-3. Usage model ........................................... 15
- 3.1 LLMNR Configuration ............................. 16
-4. Conflict Resolution ................................... 18
- 4.1 Uniqueness Verification ......................... 18
- 4.2 Conflict Detection and Defense .................. 19
- 4.3 Considerations for Multiple Interfaces .......... 20
- 4.4 API issues ...................................... 22
-5. Security Considerations ............................... 22
- 5.1 Denial of Service ............................... 22
- 5.2 Spoofing ...............,........................ 23
- 5.3 Authentication .................................. 24
- 5.4 Cache and Port Separation ....................... 24
-6. IANA considerations ................................... 25
-7. Constants ............................................. 25
-8. References ............................................ 26
- 8.1 Normative References ............................ 26
- 8.2 Informative References .......................... 26
-Acknowledgments .............................................. 28
-Authors' Addresses ........................................... 28
-Intellectual Property Statement .............................. 29
-Disclaimer of Validity ....................................... 29
-Copyright Statement .......................................... 29
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-Aboba, Thaler & Esibov Standards Track [Page 2]
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-INTERNET-DRAFT LLMNR 16 April 2006
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-
-1. Introduction
-
- This document discusses Link Local Multicast Name Resolution (LLMNR),
- which is based on the DNS packet format and supports all current and
- future DNS formats, types and classes. LLMNR operates on a separate
- port from the Domain Name System (DNS), with a distinct resolver
- cache.
-
- Since LLMNR only operates on the local link, it cannot be considered
- a substitute for DNS. Link-scope multicast addresses are used to
- prevent propagation of LLMNR traffic across routers, potentially
- flooding the network. LLMNR queries can also be sent to a unicast
- address, as described in Section 2.4.
-
- Propagation of LLMNR packets on the local link is considered
- sufficient to enable name resolution in small networks. In such
- networks, if a network has a gateway, then typically the network is
- able to provide DNS server configuration. Configuration issues are
- discussed in Section 3.1.
-
- In the future, it may be desirable to consider use of multicast name
- resolution with multicast scopes beyond the link-scope. This could
- occur if LLMNR deployment is successful, the need arises for
- multicast name resolution beyond the link-scope, or multicast routing
- becomes ubiquitous. For example, expanded support for multicast name
- resolution might be required for mobile ad-hoc networks.
-
- Once we have experience in LLMNR deployment in terms of
- administrative issues, usability and impact on the network, it will
- be possible to reevaluate which multicast scopes are appropriate for
- use with multicast name resolution. IPv4 administratively scoped
- multicast usage is specified in "Administratively Scoped IP
- Multicast" [RFC2365].
-
- Service discovery in general, as well as discovery of DNS servers
- using LLMNR in particular, is outside of the scope of this document,
- as is name resolution over non-multicast capable media.
-
-1.1. Requirements
-
- In this document, several words are used to signify the requirements
- of the specification. The key words "MUST", "MUST NOT", "REQUIRED",
- "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY",
- and "OPTIONAL" in this document are to be interpreted as described in
- [RFC2119].
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-Aboba, Thaler & Esibov Standards Track [Page 3]
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-INTERNET-DRAFT LLMNR 16 April 2006
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-1.2. Terminology
-
- This document assumes familiarity with DNS terminology defined in
- [RFC1035]. Other terminology used in this document includes:
-
-Routable Address
- An address other than a Link-Local address. This includes globally
- routable addresses, as well as private addresses.
-
-Reachable
- An LLMNR responder considers one of its addresses reachable over a
- link if it will respond to an ARP or Neighbor Discovery query for
- that address received on that link.
-
-Responder
- A host that listens to LLMNR queries, and responds to those for
- which it is authoritative.
-
-Sender
- A host that sends an LLMNR query.
-
-UNIQUE
- There are some scenarios when multiple responders may respond to
- the same query. There are other scenarios when only one responder
- may respond to a query. Names for which only a single responder is
- anticipated are referred to as UNIQUE. Name uniqueness is
- configured on the responder, and therefore uniqueness verification
- is the responder's responsibility.
-
-2. Name Resolution Using LLMNR
-
- LLMNR queries are sent to and received on port 5355. The IPv4 link-
- scope multicast address a given responder listens to, and to which a
- sender sends queries, is 224.0.0.252. The IPv6 link-scope multicast
- address a given responder listens to, and to which a sender sends all
- queries, is FF02:0:0:0:0:0:1:3.
-
- Typically a host is configured as both an LLMNR sender and a
- responder. A host MAY be configured as a sender, but not a
- responder. However, a host configured as a responder MUST act as a
- sender, if only to verify the uniqueness of names as described in
- Section 4. This document does not specify how names are chosen or
- configured. This may occur via any mechanism, including DHCPv4
- [RFC2131] or DHCPv6 [RFC3315].
-
- A typical sequence of events for LLMNR usage is as follows:
-
- [a] An LLMNR sender sends an LLMNR query to the link-scope
-
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- multicast address(es), unless a unicast query is indicated,
- as specified in Section 2.4.
-
- [b] A responder responds to this query only if it is authoritative
- for the name in the query. A responder responds to a
- multicast query by sending a unicast UDP response to the sender.
- Unicast queries are responded to as indicated in Section 2.4.
-
- [c] Upon reception of the response, the sender processes it.
-
- The sections that follow provide further details on sender and
- responder behavior.
-
-2.1. LLMNR Packet Format
-
- LLMNR is based on the DNS packet format defined in [RFC1035] Section
- 4 for both queries and responses. LLMNR implementations SHOULD send
- UDP queries and responses only as large as are known to be
- permissible without causing fragmentation. When in doubt a maximum
- packet size of 512 octets SHOULD be used. LLMNR implementations MUST
- accept UDP queries and responses as large as the smaller of the link
- MTU or 9194 octets (Ethernet jumbo frame size of 9KB (9216) minus 22
- octets for the header, VLAN tag and CRC).
-
-2.1.1. LLMNR Header Format
-
- LLMNR queries and responses utilize the DNS header format defined in
- [RFC1035] with exceptions noted below:
-
- 1 1 1 1 1 1
- 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
- +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
- | ID |
- +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
- |QR| Opcode | C|TC| T| Z| Z| Z| Z| RCODE |
- +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
- | QDCOUNT |
- +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
- | ANCOUNT |
- +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
- | NSCOUNT |
- +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
- | ARCOUNT |
- +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
-
- where:
-
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-ID A 16 bit identifier assigned by the program that generates any kind
- of query. This identifier is copied from the query to the response
- and can be used by the sender to match responses to outstanding
- queries. The ID field in a query SHOULD be set to a pseudo-random
- value. For advice on generation of pseudo-random values, please
- consult [RFC1750].
-
-QR Query/Response. A one bit field, which if set indicates that the
- message is an LLMNR response; if clear then the message is an LLMNR
- query.
-
-OPCODE
- A four bit field that specifies the kind of query in this message.
- This value is set by the originator of a query and copied into the
- response. This specification defines the behavior of standard
- queries and responses (opcode value of zero). Future
- specifications may define the use of other opcodes with LLMNR.
- LLMNR senders and responders MUST support standard queries (opcode
- value of zero). LLMNR queries with unsupported OPCODE values MUST
- be silently discarded by responders.
-
-C Conflict. When set within a request, the 'C'onflict bit indicates
- that a sender has received multiple LLMNR responses to this query.
- In an LLMNR response, if the name is considered UNIQUE, then the
- 'C' bit is clear, otherwise it is set. LLMNR senders do not
- retransmit queries with the 'C' bit set. Responders MUST NOT
- respond to LLMNR queries with the 'C' bit set, but may start the
- uniqueness verification process, as described in Section 4.2.
-
-TC TrunCation - specifies that this message was truncated due to
- length greater than that permitted on the transmission channel.
- The TC bit MUST NOT be set in an LLMNR query and if set is ignored
- by an LLMNR responder. If the TC bit is set in an LLMNR response,
- then the sender SHOULD resend the LLMNR query over TCP using the
- unicast address of the responder as the destination address. If
- the sender receives a response to the TCP query, then it SHOULD
- discard the UDP response with the TC bit set. See [RFC2181] and
- Section 2.4 of this specification for further discussion of the TC
- bit.
-
-T Tentative. The 'T'entative bit is set in a response if the
- responder is authoritative for the name, but has not yet verified
- the uniqueness of the name. A responder MUST ignore the 'T' bit in
- a query, if set. A response with the 'T' bit set is silently
- discarded by the sender, except if it is a uniqueness query, in
- which case a conflict has been detected and a responder MUST
- resolve the conflict as described in Section 4.1.
-
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-Z Reserved for future use. Implementations of this specification
- MUST set these bits to zero in both queries and responses. If
- these bits are set in a LLMNR query or response, implementations of
- this specification MUST ignore them. Since reserved bits could
- conceivably be used for different purposes than in DNS,
- implementors are advised not to enable processing of these bits in
- an LLMNR implementation starting from a DNS code base.
-
-RCODE
- Response code -- this 4 bit field is set as part of LLMNR
- responses. In an LLMNR query, the sender MUST set RCODE to zero;
- the responder ignores the RCODE and assumes it to be zero. The
- response to a multicast LLMNR query MUST have RCODE set to zero. A
- sender MUST silently discard an LLMNR response with a non-zero
- RCODE sent in response to a multicast query.
-
- If an LLMNR responder is authoritative for the name in a multicast
- query, but an error is encountered, the responder SHOULD send an
- LLMNR response with an RCODE of zero, no RRs in the answer section,
- and the TC bit set. This will cause the query to be resent using
- TCP, and allow the inclusion of a non-zero RCODE in the response to
- the TCP query. Responding with the TC bit set is preferable to not
- sending a response, since it enables errors to be diagnosed. This
- may be required, for example, when an LLMNR query includes a TSIG
- RR in the additional section, and the responder encounters a
- problem that requires returning a non-zero RCODE. TSIG error
- conditions defined in [RFC2845] include a TSIG RR in an
- unacceptable position (RCODE=1) or a TSIG RR which does not
- validate (RCODE=9 with TSIG ERROR 17 (BADKEY) or 16 (BADSIG)).
-
- Since LLMNR responders only respond to LLMNR queries for names for
- which they are authoritative, LLMNR responders MUST NOT respond
- with an RCODE of 3; instead, they should not respond at all.
-
- LLMNR implementations MUST support EDNS0 [RFC2671] and extended
- RCODE values.
-
-QDCOUNT
- An unsigned 16 bit integer specifying the number of entries in the
- question section. A sender MUST place only one question into the
- question section of an LLMNR query. LLMNR responders MUST silently
- discard LLMNR queries with QDCOUNT not equal to one. LLMNR senders
- MUST silently discard LLMNR responses with QDCOUNT not equal to
- one.
-
-ANCOUNT
- An unsigned 16 bit integer specifying the number of resource
- records in the answer section. LLMNR responders MUST silently
-
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- discard LLMNR queries with ANCOUNT not equal to zero.
-
-NSCOUNT
- An unsigned 16 bit integer specifying the number of name server
- resource records in the authority records section. Authority
- record section processing is described in Section 2.9. LLMNR
- responders MUST silently discard LLMNR queries with NSCOUNT not
- equal to zero.
-
-ARCOUNT
- An unsigned 16 bit integer specifying the number of resource
- records in the additional records section. Additional record
- section processing is described in Section 2.9.
-
-2.2. Sender Behavior
-
- A sender MAY send an LLMNR query for any legal resource record type
- (e.g., A, AAAA, PTR, SRV, etc.) to the link-scope multicast address.
- As described in Section 2.4, a sender MAY also send a unicast query.
-
- The sender MUST anticipate receiving no replies to some LLMNR
- queries, in the event that no responders are available within the
- link-scope. If no response is received, a resolver treats it as a
- response that the name does not exist (RCODE=3 is returned). A
- sender can handle duplicate responses by discarding responses with a
- source IP address and ID field that duplicate a response already
- received.
-
- When multiple valid LLMNR responses are received with the 'C' bit
- set, they SHOULD be concatenated and treated in the same manner that
- multiple RRs received from the same DNS server would be. However,
- responses with the 'C' bit set SHOULD NOT be concatenated with
- responses with the 'C' bit clear; instead, only the responses with
- the 'C' bit set SHOULD be returned. If valid LLMNR response(s) are
- received along with error response(s), then the error responses are
- silently discarded.
-
- Since the responder may order the RRs in the response so as to
- indicate preference, the sender SHOULD preserve ordering in the
- response to the querying application.
-
-2.3. Responder Behavior
-
- An LLMNR response MUST be sent to the sender via unicast.
-
- Upon configuring an IP address, responders typically will synthesize
- corresponding A, AAAA and PTR RRs so as to be able to respond to
- LLMNR queries for these RRs. An SOA RR is synthesized only when a
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- responder has another RR in addition to the SOA RR; the SOA RR MUST
- NOT be the only RR that a responder has. However, in general whether
- RRs are manually or automatically created is an implementation
- decision.
-
- For example, a host configured to have computer name "host1" and to
- be a member of the "example.com" domain, and with IPv4 address
- 192.0.2.1 and IPv6 address 2001:0DB8::1:2:3:FF:FE:4:5:6 might be
- authoritative for the following records:
-
- host1. IN A 192.0.2.1
- IN AAAA 2001:0DB8::1:2:3:FF:FE:4:5:6
-
- host1.example.com. IN A 192.0.2.1
- IN AAAA 2001:0DB8::1:2:3:FF:FE:4:5:6
-
- 1.2.0.192.in-addr.arpa. IN PTR host1.
- IN PTR host1.example.com.
-
- 6.0.5.0.4.0.E.F.F.F.3.0.2.0.1.0.0.0.0.0.0.0.0.0.8.b.d.0.1.0.0.2.
- ip6.arpa IN PTR host1. (line split for formatting reasons)
- IN PTR host1.example.com.
-
- An LLMNR responder might be further manually configured with the name
- of a local mail server with an MX RR included in the "host1." and
- "host1.example.com." records.
-
- In responding to queries:
-
-[a] Responders MUST listen on UDP port 5355 on the link-scope multicast
- address(es) defined in Section 2, and on TCP port 5355 on the
- unicast address(es) that could be set as the source address(es)
- when the responder responds to the LLMNR query.
-
-[b] Responders MUST direct responses to the port from which the query
- was sent. When queries are received via TCP this is an inherent
- part of the transport protocol. For queries received by UDP the
- responder MUST take note of the source port and use that as the
- destination port in the response. Responses MUST always be sent
- from the port to which they were directed.
-
-[c] Responders MUST respond to LLMNR queries for names and addresses
- they are authoritative for. This applies to both forward and
- reverse lookups, with the exception of queries with the 'C' bit
- set, which do not elicit a response.
-
-[d] Responders MUST NOT respond to LLMNR queries for names they are not
- authoritative for.
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-[e] Responders MUST NOT respond using data from the LLMNR or DNS
- resolver cache.
-
-[f] If a DNS server is running on a host that supports LLMNR, the DNS
- server MUST respond to LLMNR queries only for the RRSets relating
- to the host on which the server is running, but MUST NOT respond
- for other records for which the server is authoritative. DNS
- servers also MUST NOT send LLMNR queries in order to resolve DNS
- queries.
-
-[g] If a responder is authoritative for a name, it MUST respond with
- RCODE=0 and an empty answer section, if the type of query does not
- match a RR that the responder has.
-
- As an example, a host configured to respond to LLMNR queries for the
- name "foo.example.com." is authoritative for the name
- "foo.example.com.". On receiving an LLMNR query for an A RR with the
- name "foo.example.com." the host authoritatively responds with A
- RR(s) that contain IP address(es) in the RDATA of the resource
- record. If the responder has a AAAA RR, but no A RR, and an A RR
- query is received, the responder would respond with RCODE=0 and an
- empty answer section.
-
- In conventional DNS terminology a DNS server authoritative for a zone
- is authoritative for all the domain names under the zone apex except
- for the branches delegated into separate zones. Contrary to
- conventional DNS terminology, an LLMNR responder is authoritative
- only for the zone apex.
-
- For example the host "foo.example.com." is not authoritative for the
- name "child.foo.example.com." unless the host is configured with
- multiple names, including "foo.example.com." and
- "child.foo.example.com.". As a result, "foo.example.com." cannot
- reply to an LLMNR query for "child.foo.example.com." with RCODE=3
- (authoritative name error). The purpose of limiting the name
- authority scope of a responder is to prevent complications that could
- be caused by coexistence of two or more hosts with the names
- representing child and parent (or grandparent) nodes in the DNS tree,
- for example, "foo.example.com." and "child.foo.example.com.".
-
- Without the restriction on authority an LLMNR query for an A resource
- record for the name "child.foo.example.com." would result in two
- authoritative responses: RCODE=3 (authoritative name error) received
- from "foo.example.com.", and a requested A record - from
- "child.foo.example.com.". To prevent this ambiguity, LLMNR enabled
- hosts could perform a dynamic update of the parent (or grandparent)
- zone with a delegation to a child zone; for example a host
- "child.foo.example.com." could send a dynamic update for the NS and
-
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- glue A record to "foo.example.com.". However, this approach
- significantly complicates implementation of LLMNR and would not be
- acceptable for lightweight hosts.
-
-2.4. Unicast Queries and Responses
-
- Unicast queries SHOULD be sent when:
-
- [a] A sender repeats a query after it received a response
- with the TC bit set to the previous LLMNR multicast query, or
-
- [b] The sender queries for a PTR RR of a fully formed IP address
- within the "in-addr.arpa" or "ip6.arpa" zones.
-
- Unicast LLMNR queries MUST be done using TCP and the responses MUST
- be sent using the same TCP connection as the query. Senders MUST
- support sending TCP queries, and responders MUST support listening
- for TCP queries. If the sender of a TCP query receives a response to
- that query not using TCP, the response MUST be silently discarded.
-
- Unicast UDP queries MUST be silently discarded.
-
- A unicast PTR RR query for an off-link address will not elicit a
- response, but instead an ICMP TTL or Hop Limit exceeded message will
- be received. An implementation receiving an ICMP message in response
- to a TCP connection setup attempt can return immediately, treating
- this as a response that no such name exists (RCODE=3 is returned).
- An implementation that cannot process ICMP messages MAY send
- multicast UDP queries for PTR RRs. Since TCP implementations will
- not retransmit prior to RTOmin, a considerable period will elapse
- before TCP retransmits multiple times, resulting in a long timeout
- for TCP PTR RR queries sent to an off-link destination.
-
-2.5. "Off link" Detection
-
- A sender MUST select a source address for LLMNR queries that is
- assigned on the interface on which the query is sent. The
- destination address of an LLMNR query MUST be a link-scope multicast
- address or a unicast address.
-
- A responder MUST select a source address for responses that is
- assigned on the interface on which the query was received. The
- destination address of an LLMNR response MUST be a unicast address.
-
- On receiving an LLMNR query, the responder MUST check whether it was
- sent to a LLMNR multicast addresses defined in Section 2. If it was
- sent to another multicast address, then the query MUST be silently
- discarded.
-
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- Section 2.4 discusses use of TCP for LLMNR queries and responses. In
- composing an LLMNR query using TCP, the sender MUST set the Hop Limit
- field in the IPv6 header and the TTL field in the IPv4 header of the
- response to one (1). The responder SHOULD set the TTL or Hop Limit
- settings on the TCP listen socket to one (1) so that SYN-ACK packets
- will have TTL (IPv4) or Hop Limit (IPv6) set to one (1). This
- prevents an incoming connection from off-link since the sender will
- not receive a SYN-ACK from the responder.
-
- For UDP queries and responses, the Hop Limit field in the IPv6 header
- and the TTL field in the IPV4 header MAY be set to any value.
- However, it is RECOMMENDED that the value 255 be used for
- compatibility with early implementations of [RFC3927].
-
- Implementation note:
-
- In the sockets API for IPv4 [POSIX], the IP_TTL and
- IP_MULTICAST_TTL socket options are used to set the TTL of
- outgoing unicast and multicast packets. The IP_RECVTTL socket
- option is available on some platforms to retrieve the IPv4 TTL of
- received packets with recvmsg(). [RFC2292] specifies similar
- options for setting and retrieving the IPv6 Hop Limit.
-
-2.6. Responder Responsibilities
-
- It is the responsibility of the responder to ensure that RRs returned
- in LLMNR responses MUST only include values that are valid on the
- local interface, such as IPv4 or IPv6 addresses valid on the local
- link or names defended using the mechanism described in Section 4.
- IPv4 Link-Local addresses are defined in [RFC3927]. IPv6 Link-Local
- addresses are defined in [RFC2373]. In particular:
-
- [a] If a link-scope IPv6 address is returned in a AAAA RR,
- that address MUST be valid on the local link over which
- LLMNR is used.
-
- [b] If an IPv4 address is returned, it MUST be reachable
- through the link over which LLMNR is used.
-
- [c] If a name is returned (for example in a CNAME, MX
- or SRV RR), the name MUST be resolvable on the local
- link over which LLMNR is used.
-
- Where multiple addresses represent valid responses to a query, the
- order in which the addresses are returned is as follows:
-
- [d] If the source address of the query is a link-scope address,
- then the responder SHOULD include a link-scope address first
-
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- in the response, if available.
-
- [e] If the source address of the query is a routable address,
- then the responder MUST include a routable address first
- in the response, if available.
-
-2.7. Retransmission and Jitter
-
- An LLMNR sender uses the timeout interval LLMNR_TIMEOUT to determine
- when to retransmit an LLMNR query. An LLMNR sender SHOULD either
- estimate the LLMNR_TIMEOUT for each interface, or set a reasonably
- high initial timeout. Suggested constants are described in Section
- 7.
-
- If an LLMNR query sent over UDP is not resolved within LLMNR_TIMEOUT,
- then a sender SHOULD repeat the transmission of the query in order to
- assure that it was received by a host capable of responding to it.
- An LLMNR query SHOULD NOT be sent more than three times.
-
- Where LLMNR queries are sent using TCP, retransmission is handled by
- the transport layer. Queries with the 'C' bit set MUST be sent using
- multicast UDP and MUST NOT be retransmitted.
-
- An LLMNR sender cannot know in advance if a query sent using
- multicast will receive no response, one response, or more than one
- response. An LLMNR sender MUST wait for LLMNR_TIMEOUT if no response
- has been received, or if it is necessary to collect all potential
- responses, such as if a uniqueness verification query is being made.
- Otherwise an LLMNR sender SHOULD consider a multicast query answered
- after the first response is received, if that response has the 'C'
- bit clear.
-
- However, if the first response has the 'C' bit set, then the sender
- SHOULD wait for LLMNR_TIMEOUT + JITTER_INTERVAL in order to collect
- all possible responses. When multiple valid answers are received,
- they may first be concatenated, and then treated in the same manner
- that multiple RRs received from the same DNS server would. A unicast
- query sender considers the query answered after the first response is
- received.
-
- Since it is possible for a response with the 'C' bit clear to be
- followed by a response with the 'C' bit set, an LLMNR sender SHOULD
- be prepared to process additional responses for the purposes of
- conflict detection, even after it has considered a query answered.
-
- In order to avoid synchronization, the transmission of each LLMNR
- query and response SHOULD delayed by a time randomly selected from
- the interval 0 to JITTER_INTERVAL. This delay MAY be avoided by
-
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- responders responding with names which they have previously
- determined to be UNIQUE (see Section 4 for details).
-
-2.8. DNS TTL
-
- The responder should insert a pre-configured TTL value in the records
- returned in an LLMNR response. A default value of 30 seconds is
- RECOMMENDED. In highly dynamic environments (such as mobile ad-hoc
- networks), the TTL value may need to be reduced.
-
- Due to the TTL minimalization necessary when caching an RRset, all
- TTLs in an RRset MUST be set to the same value.
-
-2.9. Use of the Authority and Additional Sections
-
- Unlike the DNS, LLMNR is a peer-to-peer protocol and does not have a
- concept of delegation. In LLMNR, the NS resource record type may be
- stored and queried for like any other type, but it has no special
- delegation semantics as it does in the DNS. Responders MAY have NS
- records associated with the names for which they are authoritative,
- but they SHOULD NOT include these NS records in the authority
- sections of responses.
-
- Responders SHOULD insert an SOA record into the authority section of
- a negative response, to facilitate negative caching as specified in
- [RFC2308]. The TTL of this record is set from the minimum of the
- MINIMUM field of the SOA record and the TTL of the SOA itself, and
- indicates how long a resolver may cache the negative answer. The
- owner name of the SOA record (MNAME) MUST be set to the query name.
- The RNAME, SERIAL, REFRESH, RETRY and EXPIRE values MUST be ignored
- by senders. Negative responses without SOA records SHOULD NOT be
- cached.
-
- In LLMNR, the additional section is primarily intended for use by
- EDNS0, TSIG and SIG(0). As a result, unless the 'C' bit is set,
- senders MAY only include pseudo RR-types in the additional section of
- a query; unless the 'C' bit is set, responders MUST ignore the
- additional section of queries containing other RR types.
-
- In queries where the 'C' bit is set, the sender SHOULD include the
- conflicting RRs in the additional section. Since conflict
- notifications are advisory, responders SHOULD log information from
- the additional section, but otherwise MUST ignore the additional
- section.
-
- Senders MUST NOT cache RRs from the authority or additional section
- of a response as answers, though they may be used for other purposes
- such as negative caching.
-
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-3. Usage Model
-
- LLMNR is a peer-to-peer name resolution protocol that is not intended
- as a replacement for DNS; rather, it enables name resolution in
- scenarios in which conventional DNS name resolution is not possible.
- This includes situations in which hosts are not configured with the
- address of a DNS server; where the DNS server is unavailable or
- unreachable; where there is no DNS server authoritative for the name
- of a host, or where the authoritative DNS server does not have the
- desired RRs.
-
- By default, an LLMNR sender SHOULD send LLMNR queries only for
- single-label names. In order to reduce unnecessary DNS queries, stub
- resolvers supporting both DNS and LLMNR SHOULD avoid sending DNS
- queries for single-label names. An LLMNR sender SHOULD NOT be
- enabled to send a query for any name, except where security
- mechanisms (described in Section 5.3) can be utilized.
-
- Regardless of whether security mechanisms can be utilized, LLMNR
- queries SHOULD NOT be sent unless one of the following conditions are
- met:
-
- [1] No manual or automatic DNS configuration has been performed.
- If DNS server address(es) have been configured, a
- host SHOULD attempt to reach DNS servers over all protocols
- on which DNS server address(es) are configured, prior to sending
- LLMNR queries. For dual stack hosts configured with DNS server
- address(es) for one protocol but not another, this implies that
- DNS queries SHOULD be sent over the protocol configured with
- a DNS server, prior to sending LLMNR queries.
-
- [2] All attempts to resolve the name via DNS on all interfaces
- have failed after exhausting the searchlist. This can occur
- because DNS servers did not respond, or because they
- responded to DNS queries with RCODE=3 (Authoritative Name
- Error) or RCODE=0, and an empty answer section. Where a
- single resolver call generates DNS queries for A and AAAA RRs,
- an implementation MAY choose not to send LLMNR queries if any
- of the DNS queries is successful. An LLMNR query SHOULD only
- be sent for the originally requested name; a searchlist
- is not used to form additional LLMNR queries.
-
- Since LLMNR is a secondary name resolution mechanism, its usage is in
- part determined by the behavior of DNS implementations. In general,
- robust DNS resolver implementations are more likely to avoid
- unnecessary LLMNR queries.
-
- As noted in [DNSPerf], even when DNS servers are configured, a
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- significant fraction of DNS queries do not receive a response, or
- result in negative responses due to missing inverse mappings or NS
- records that point to nonexistent or inappropriate hosts. This has
- the potential to result in a large number of unnecessary LLMNR
- queries.
-
- [RFC1536] describes common DNS implementation errors and fixes. If
- the proposed fixes are implemented, unnecessary LLMNR queries will be
- reduced substantially, and so implementation of [RFC1536] is
- recommended.
-
- For example, [RFC1536] Section 1 describes issues with retransmission
- and recommends implementation of a retransmission policy based on
- round trip estimates, with exponential back-off. [RFC1536] Section 4
- describes issues with failover, and recommends that resolvers try
- another server when they don't receive a response to a query. These
- policies are likely to avoid unnecessary LLMNR queries.
-
- [RFC1536] Section 3 describes zero answer bugs, which if addressed
- will also reduce unnecessary LLMNR queries.
-
- [RFC1536] Section 6 describes name error bugs and recommended
- searchlist processing that will reduce unnecessary RCODE=3
- (authoritative name) errors, thereby also reducing unnecessary LLMNR
- queries.
-
- If error responses are received from both DNS and LLMNR, then the
- lowest RCODE value should be returned. For example, if either DNS or
- LLMNR receives a response with RCODE=0, then this should returned to
- the caller.
-
-3.1. LLMNR Configuration
-
- LLMNR usage MAY be configured manually or automatically on a per
- interface basis. By default, LLMNR responders SHOULD be enabled on
- all interfaces, at all times. Enabling LLMNR for use in situations
- where a DNS server has been configured will result in a change in
- default behavior without a simultaneous update to configuration
- information. Where this is considered undesirable, LLMNR SHOULD NOT
- be enabled by default, so that hosts will neither listen on the link-
- scope multicast address, nor will they send queries to that address.
-
- Since IPv4 and IPv6 utilize distinct configuration mechanisms, it is
- possible for a dual stack host to be configured with the address of a
- DNS server over IPv4, while remaining unconfigured with a DNS server
- suitable for use over IPv6.
-
- In these situations, a dual stack host will send AAAA queries to the
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- configured DNS server over IPv4. However, an IPv6-only host
- unconfigured with a DNS server suitable for use over IPv6 will be
- unable to resolve names using DNS. Automatic IPv6 DNS configuration
- mechanisms (such as [RFC3315] and [DNSDisc]) are not yet widely
- deployed, and not all DNS servers support IPv6. Therefore lack of
- IPv6 DNS configuration may be a common problem in the short term, and
- LLMNR may prove useful in enabling link-local name resolution over
- IPv6.
-
- Where a DHCPv4 server is available but not a DHCPv6 server [RFC3315],
- IPv6-only hosts may not be configured with a DNS server. Where there
- is no DNS server authoritative for the name of a host or the
- authoritative DNS server does not support dynamic client update over
- IPv6 or DHCPv6-based dynamic update, then an IPv6-only host will not
- be able to do DNS dynamic update, and other hosts will not be able to
- resolve its name.
-
- For example, if the configured DNS server responds to a AAAA RR query
- sent over IPv4 or IPv6 with an authoritative name error (RCODE=3) or
- RCODE=0 and an empty answer section, then a AAAA RR query sent using
- LLMNR over IPv6 may be successful in resolving the name of an
- IPv6-only host on the local link.
-
- Similarly, if a DHCPv4 server is available providing DNS server
- configuration, and DNS server(s) exist which are authoritative for
- the A RRs of local hosts and support either dynamic client update
- over IPv4 or DHCPv4-based dynamic update, then the names of local
- IPv4 hosts can be resolved over IPv4 without LLMNR. However, if no
- DNS server is authoritative for the names of local hosts, or the
- authoritative DNS server(s) do not support dynamic update, then LLMNR
- enables linklocal name resolution over IPv4.
-
- Where DHCPv4 or DHCPv6 is implemented, DHCP options can be used to
- configure LLMNR on an interface. The LLMNR Enable Option, described
- in [LLMNREnable], can be used to explicitly enable or disable use of
- LLMNR on an interface. The LLMNR Enable Option does not determine
- whether or in which order DNS itself is used for name resolution.
- The order in which various name resolution mechanisms should be used
- can be specified using the Name Service Search Option (NSSO) for DHCP
- [RFC2937], using the LLMNR Enable Option code carried in the NSSO
- data.
-
- It is possible that DNS configuration mechanisms will go in and out
- of service. In these circumstances, it is possible for hosts within
- an administrative domain to be inconsistent in their DNS
- configuration.
-
- For example, where DHCP is used for configuring DNS servers, one or
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- more DHCP servers can fail. As a result, hosts configured prior to
- the outage will be configured with a DNS server, while hosts
- configured after the outage will not. Alternatively, it is possible
- for the DNS configuration mechanism to continue functioning while
- configured DNS servers fail.
-
- An outage in the DNS configuration mechanism may result in hosts
- continuing to use LLMNR even once the outage is repaired. Since
- LLMNR only enables linklocal name resolution, this represents a
- degradation in capabilities. As a result, hosts without a configured
- DNS server may wish to periodically attempt to obtain DNS
- configuration if permitted by the configuration mechanism in use. In
- the absence of other guidance, a default retry interval of one (1)
- minute is RECOMMENDED.
-
-4. Conflict Resolution
-
- By default, a responder SHOULD be configured to behave as though its
- name is UNIQUE on each interface on which LLMNR is enabled. However,
- it is also possible to configure multiple responders to be
- authoritative for the same name. For example, multiple responders
- MAY respond to a query for an A or AAAA type record for a cluster
- name (assigned to multiple hosts in the cluster).
-
- To detect duplicate use of a name, an administrator can use a name
- resolution utility which employs LLMNR and lists both responses and
- responders. This would allow an administrator to diagnose behavior
- and potentially to intervene and reconfigure LLMNR responders who
- should not be configured to respond to the same name.
-
-4.1. Uniqueness Verification
-
- Prior to sending an LLMNR response with the 'T' bit clear, a
- responder configured with a UNIQUE name MUST verify that there is no
- other host within the scope of LLMNR query propagation that is
- authoritative for the same name on that interface.
-
- Once a responder has verified that its name is UNIQUE, if it receives
- an LLMNR query for that name, with the 'C' bit clear, it MUST
- respond, with the 'T' bit clear. Prior to verifying that its name is
- UNIQUE, a responder MUST set the 'T' bit in responses.
-
- Uniqueness verification is carried out when the host:
-
- - starts up or is rebooted
- - wakes from sleep (if the network interface was inactive
- during sleep)
- - is configured to respond to LLMNR queries on an interface
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- enabled for transmission and reception of IP traffic
- - is configured to respond to LLMNR queries using additional
- UNIQUE resource records
- - verifies the acquisition of a new IP address and configuration
- on an interface
-
- To verify uniqueness, a responder MUST send an LLMNR query with the
- 'C' bit clear, over all protocols on which it responds to LLMNR
- queries (IPv4 and/or IPv6). It is RECOMMENDED that responders verify
- uniqueness of a name by sending a query for the name with type='ANY'.
-
- If no response is received, the sender retransmits the query, as
- specified in Section 2.7. If a response is received, the sender MUST
- check if the source address matches the address of any of its
- interfaces; if so, then the response is not considered a conflict,
- since it originates from the sender. To avoid triggering conflict
- detection, a responder that detects that it is connected to the same
- link on multiple interfaces SHOULD set the 'C' bit in responses.
-
- If a response is received with the 'T' bit clear, the responder MUST
- NOT use the name in response to LLMNR queries received over any
- protocol (IPv4 or IPv6). If a response is received with the 'T' bit
- set, the responder MUST check if the source IP address in the
- response, interpreted as an unsigned integer, is less than the source
- IP address in the query. If so, the responder MUST NOT use the name
- in response to LLMNR queries received over any protocol (IPv4 or
- IPv6). For the purpose of uniqueness verification, the contents of
- the answer section in a response is irrelevant.
-
- Periodically carrying out uniqueness verification in an attempt to
- detect name conflicts is not necessary, wastes network bandwidth, and
- may actually be detrimental. For example, if network links are
- joined only briefly, and are separated again before any new
- communication is initiated, temporary conflicts are benign and no
- forced reconfiguration is required. LLMNR responders SHOULD NOT
- periodically attempt uniqueness verification.
-
-4.2. Conflict Detection and Defense
-
- Hosts on disjoint network links may configure the same name for use
- with LLMNR. If these separate network links are later joined or
- bridged together, then there may be multiple hosts which are now on
- the same link, trying to use the same name.
-
- In order to enable ongoing detection of name conflicts, when an LLMNR
- sender receives multiple LLMNR responses to a query, it MUST check if
- the 'C' bit is clear in any of the responses. If so, the sender
- SHOULD send another query for the same name, type and class, this
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- time with the 'C' bit set, with the potentially conflicting resource
- records included in the additional section.
-
- Queries with the 'C' bit set are considered advisory and responders
- MUST verify the existence of a conflict before acting on it. A
- responder receiving a query with the 'C' bit set MUST NOT respond.
-
- If the query is for a UNIQUE name, then the responder MUST send its
- own query for the same name, type and class, with the 'C' bit clear.
- If a response is received, the sender MUST check if the source
- address matches the address of any of its interfaces; if so, then the
- response is not considered a conflict, since it originates from the
- sender. To avoid triggering conflict detection, a responder that
- detects that it is connected to the same link on multiple interfaces
- SHOULD set the 'C' bit in responses.
-
- An LLMNR responder MUST NOT ignore conflicts once detected and SHOULD
- log them. Upon detecting a conflict, an LLMNR responder MUST
- immediately stop using the conflicting name in response to LLMNR
- queries received over any supported protocol, if the source IP
- address in the response, interpreted as an unsigned integer, is less
- than the source IP address in the uniqueness verification query.
-
- After stopping the use of a name, the responder MAY elect to
- configure a new name. However, since name reconfiguration may be
- disruptive, this is not required, and a responder may have been
- configured to respond to multiple names so that alternative names may
- already be available. A host that has stopped the use of a name may
- attempt uniqueness verification again after the expiration of the TTL
- of the conflicting response.
-
-4.3. Considerations for Multiple Interfaces
-
- A multi-homed host may elect to configure LLMNR on only one of its
- active interfaces. In many situations this will be adequate.
- However, should a host need to configure LLMNR on more than one of
- its active interfaces, there are some additional precautions it MUST
- take. Implementers who are not planning to support LLMNR on multiple
- interfaces simultaneously may skip this section.
-
- Where a host is configured to issue LLMNR queries on more than one
- interface, each interface maintains its own independent LLMNR
- resolver cache, containing the responses to LLMNR queries.
-
- A multi-homed host checks the uniqueness of UNIQUE records as
- described in Section 4. The situation is illustrated in figure 1.
-
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- ---------- ----------
- | | | |
- [A] [myhost] [myhost]
-
- Figure 1. Link-scope name conflict
-
- In this situation, the multi-homed myhost will probe for, and defend,
- its host name on both interfaces. A conflict will be detected on one
- interface, but not the other. The multi-homed myhost will not be
- able to respond with a host RR for "myhost" on the interface on the
- right (see Figure 1). The multi-homed host may, however, be
- configured to use the "myhost" name on the interface on the left.
-
- Since names are only unique per-link, hosts on different links could
- be using the same name. If an LLMNR client sends requests over
- multiple interfaces, and receives replies from more than one, the
- result returned to the client is defined by the implementation. The
- situation is illustrated in figure 2.
-
- ---------- ----------
- | | | |
- [A] [myhost] [A]
-
-
- Figure 2. Off-segment name conflict
-
- If host myhost is configured to use LLMNR on both interfaces, it will
- send LLMNR queries on both interfaces. When host myhost sends a
- query for the host RR for name "A" it will receive a response from
- hosts on both interfaces.
-
- Host myhost cannot distinguish between the situation shown in Figure
- 2, and that shown in Figure 3 where no conflict exists.
-
- [A]
- | |
- ----- -----
- | |
- [myhost]
-
- Figure 3. Multiple paths to same host
-
- This illustrates that the proposed name conflict resolution mechanism
- does not support detection or resolution of conflicts between hosts
- on different links. This problem can also occur with DNS when a
- multi-homed host is connected to two different networks with
- separated name spaces. It is not the intent of this document to
- address the issue of uniqueness of names within DNS.
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-4.4. API Issues
-
- [RFC2553] provides an API which can partially solve the name
- ambiguity problem for applications written to use this API, since the
- sockaddr_in6 structure exposes the scope within which each scoped
- address exists, and this structure can be used for both IPv4 (using
- v4-mapped IPv6 addresses) and IPv6 addresses.
-
- Following the example in Figure 2, an application on 'myhost' issues
- the request getaddrinfo("A", ...) with ai_family=AF_INET6 and
- ai_flags=AI_ALL|AI_V4MAPPED. LLMNR requests will be sent from both
- interfaces and the resolver library will return a list containing
- multiple addrinfo structures, each with an associated sockaddr_in6
- structure. This list will thus contain the IPv4 and IPv6 addresses
- of both hosts responding to the name 'A'. Link-local addresses will
- have a sin6_scope_id value that disambiguates which interface is used
- to reach the address. Of course, to the application, Figures 2 and 3
- are still indistinguishable, but this API allows the application to
- communicate successfully with any address in the list.
-
-5. Security Considerations
-
- LLMNR is a peer-to-peer name resolution protocol designed for use on
- the local link. While LLMNR limits the vulnerability of responders
- to off-link senders, it is possible for an off-link responder to
- reach a sender.
-
- In scenarios such as public "hotspots" attackers can be present on
- the same link. These threats are most serious in wireless networks
- such as 802.11, since attackers on a wired network will require
- physical access to the network, while wireless attackers may mount
- attacks from a distance. Link-layer security such as [IEEE-802.11i]
- can be of assistance against these threats if it is available.
-
- This section details security measures available to mitigate threats
- from on and off-link attackers.
-
-5.1. Denial of Service
-
- Attackers may take advantage of LLMNR conflict detection by
- allocating the same name, denying service to other LLMNR responders
- and possibly allowing an attacker to receive packets destined for
- other hosts. By logging conflicts, LLMNR responders can provide
- forensic evidence of these attacks.
-
- An attacker may spoof LLMNR queries from a victim's address in order
- to mount a denial of service attack. Responders setting the IPv6 Hop
- Limit or IPv4 TTL field to a value larger than one in an LLMNR UDP
-
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- response may be able to reach the victim across the Internet.
-
- While LLMNR responders only respond to queries for which they are
- authoritative and LLMNR does not provide wildcard query support, an
- LLMNR response may be larger than the query, and an attacker can
- generate multiple responses to a query for a name used by multiple
- responders. A sender may protect itself against unsolicited
- responses by silently discarding them as rapidly as possible.
-
-5.2. Spoofing
-
- LLMNR is designed to prevent reception of queries sent by an off-link
- attacker. LLMNR requires that responders receiving UDP queries check
- that they are sent to a link-scope multicast address. However, it is
- possible that some routers may not properly implement link-scope
- multicast, or that link-scope multicast addresses may leak into the
- multicast routing system. To prevent successful setup of TCP
- connections by an off-link sender, responders receiving a TCP SYN
- reply with a TCP SYN-ACK with TTL set to one (1).
-
- While it is difficult for an off-link attacker to send an LLMNR query
- to a responder, it is possible for an off-link attacker to spoof a
- response to a query (such as an A or AAAA query for a popular
- Internet host), and by using a TTL or Hop Limit field larger than one
- (1), for the forged response to reach the LLMNR sender. Since the
- forged response will only be accepted if it contains a matching ID
- field, choosing a pseudo-random ID field within queries provides some
- protection against off-link responders.
-
- Since LLMNR queries can be sent when DNS server(s) do not respond, an
- attacker can execute a denial of service attack on the DNS server(s)
- and then poison the LLMNR cache by responding to an LLMNR query with
- incorrect information. As noted in "Threat Analysis of the Domain
- Name System (DNS)" [RFC3833] these threats also exist with DNS, since
- DNS response spoofing tools are available that can allow an attacker
- to respond to a query more quickly than a distant DNS server.
- However, while switched networks or link layer security may make it
- difficult for an on-link attacker to snoop unicast DNS queries,
- multicast LLMNR queries are propagated to all hosts on the link,
- making it possible for an on-link attacker to spoof LLMNR responses
- without having to guess the value of the ID field in the query.
-
- Since LLMNR queries are sent and responded to on the local-link, an
- attacker will need to respond more quickly to provide its own
- response prior to arrival of the response from a legitimate
- responder. If an LLMNR query is sent for an off-link host, spoofing
- a response in a timely way is not difficult, since a legitimate
- response will never be received.
-
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- This vulnerability can be reduced by limiting use of LLMNR to
- resolution of single-label names as described in Section 3, or by
- implementation of authentication (see Section 5.3).
-
-5.3. Authentication
-
- LLMNR is a peer-to-peer name resolution protocol, and as a result,
- it is often deployed in situations where no trust model can be
- assumed. Where a pre-arranged security configuration is possible,
- the following security mechanisms may be used:
-
-[a] LLMNR implementations MAY support TSIG [RFC2845] and/or SIG(0)
- [RFC2931] security mechanisms. "DNS Name Service based on Secure
- Multicast DNS for IPv6 Mobile Ad Hoc Networks" [LLMNRSec] describes
- the use of TSIG to secure LLMNR, based on group keys. While group
- keys can be used to demonstrate membership in a group, they do not
- protect against forgery by an attacker that is a member of the
- group.
-
-[b] IPsec ESP with a null-transform MAY be used to authenticate unicast
- LLMNR queries and responses or LLMNR responses to multicast
- queries. In a small network without a certificate authority, this
- can be most easily accomplished through configuration of a group
- pre-shared key for trusted hosts. As with TSIG, this does not
- protect against forgery by an attacker with access to the group
- pre-shared key.
-
-[c] LLMNR implementations MAY support DNSSEC [RFC4033]. In order to
- support DNSSEC, LLMNR implementations MAY be configured with trust
- anchors, or they MAY make use of keys obtained from DNS queries.
- Since LLMNR does not support "delegated trust" (CD or AD bits),
- LLMNR implementations cannot make use of DNSSEC unless they are
- DNSSEC-aware and support validation. Unlike approaches [a] or [b],
- DNSSEC permits a responder to demonstrate ownership of a name, not
- just membership within a trusted group. As a result, it enables
- protection against forgery.
-
-5.4. Cache and Port Separation
-
- In order to prevent responses to LLMNR queries from polluting the DNS
- cache, LLMNR implementations MUST use a distinct, isolated cache for
- LLMNR on each interface. The use of separate caches is most
- effective when LLMNR is used as a name resolution mechanism of last
- resort, since this minimizes the opportunities for poisoning the
- LLMNR cache, and decreases reliance on it.
-
- LLMNR operates on a separate port from DNS, reducing the likelihood
- that a DNS server will unintentionally respond to an LLMNR query.
-
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- If LLMNR is given higher priority than DNS among the enabled name
- resolution mechanisms, a denial of service attack on the DNS server
- would not be necessary in order to poison the LLMNR cache, since
- LLMNR queries would be sent even when the DNS server is available.
- In addition, the LLMNR cache, once poisoned, would take precedence
- over the DNS cache, eliminating the benefits of cache separation. As
- a result, LLMNR SHOULD NOT be used as a primary name resolution
- mechanism.
-
-6. IANA Considerations
-
- LLMNR requires allocation of port 5355 for both TCP and UDP.
-
- LLMNR requires allocation of link-scope multicast IPv4 address
- 224.0.0.252, as well as link-scope multicast IPv6 address
- FF02:0:0:0:0:0:1:3.
-
- This specification creates two new name spaces: the LLMNR namespace
- and the reserved bits in the LLMNR header. The reserved bits in the
- LLMNR header are allocated by IETF Consensus, in accordance with BCP
- 26 [RFC2434].
-
- In order to to avoid creating any new administrative procedures,
- administration of the LLMNR namespace will piggyback on the
- administration of the DNS namespace.
-
- The rights to use a fully qualified domain name (FQDN) within LLMNR
- are obtained coincident with acquiring the rights to use that name
- within DNS. Those wishing to use a FQDN within LLMNR should first
- acquire the rights to use the corresponding FQDN within DNS. Using a
- FQDN within LLMNR without ownership of the corresponding name in DNS
- creates the possibility of conflict and therefore is discouraged.
-
- LLMNR responders may self-allocate a name within the single-label
- name space, first defined in [RFC1001]. Since single-label names are
- not unique, no registration process is required.
-
-7. Constants
-
- The following timing constants are used in this protocol; they are
- not intended to be user configurable.
-
- JITTER_INTERVAL 100 ms
- LLMNR_TIMEOUT 1 second (if set statically on all interfaces)
- 100 ms (IEEE 802 media, including IEEE 802.11)
-
-
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-8. References
-
-8.1. Normative References
-
-[RFC1001] Auerbach, K. and A. Aggarwal, "Protocol Standard for a NetBIOS
- Service on a TCP/UDP Transport: Concepts and Methods", RFC
- 1001, March 1987.
-
-[RFC1035] Mockapetris, P., "Domain Names - Implementation and
- Specification", RFC 1035, November 1987.
-
-[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
- Requirement Levels", BCP 14, RFC 2119, March 1997.
-
-[RFC2181] Elz, R. and R. Bush, "Clarifications to the DNS
- Specification", RFC 2181, July 1997.
-
-[RFC2308] Andrews, M., "Negative Caching of DNS Queries (DNS NCACHE)",
- RFC 2308, March 1998.
-
-[RFC2373] Hinden, R. and S. Deering, "IP Version 6 Addressing
- Architecture", RFC 2373, July 1998.
-
-[RFC2434] Alvestrand, H. and T. Narten, "Guidelines for Writing an IANA
- Considerations Section in RFCs", BCP 26, RFC 2434, October
- 1998.
-
-[RFC2671] Vixie, P., "Extension Mechanisms for DNS (EDNS0)", RFC 2671,
- August 1999.
-
-[RFC2845] Vixie, P., Gudmundsson, O., Eastlake, D. and B. Wellington,
- "Secret Key Transaction Authentication for DNS (TSIG)", RFC
- 2845, May 2000.
-
-[RFC2931] Eastlake, D., "DNS Request and Transaction Signatures
- (SIG(0)s)", RFC 2931, September 2000.
-
-8.2. Informative References
-
-[DNSPerf] Jung, J., et al., "DNS Performance and the Effectiveness of
- Caching", IEEE/ACM Transactions on Networking, Volume 10,
- Number 5, pp. 589, October 2002.
-
-[DNSDisc] Durand, A., Hagino, I. and D. Thaler, "Well known site local
- unicast addresses to communicate with recursive DNS servers",
- Internet draft (work in progress), draft-ietf-ipv6-dns-
- discovery-07.txt, October 2002.
-
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-[IEEE-802.11i]
- Institute of Electrical and Electronics Engineers, "Supplement
- to Standard for Telecommunications and Information Exchange
- Between Systems - LAN/MAN Specific Requirements - Part 11:
- Wireless LAN Medium Access Control (MAC) and Physical Layer
- (PHY) Specifications: Specification for Enhanced Security",
- IEEE 802.11i, July 2004.
-
-[LLMNREnable]
- Guttman, E., "DHCP LLMNR Enable Option", Internet draft (work
- in progress), draft-guttman-mdns-enable-02.txt, April 2002.
-
-[LLMNRSec]
- Jeong, J., Park, J. and H. Kim, "DNS Name Service based on
- Secure Multicast DNS for IPv6 Mobile Ad Hoc Networks", ICACT
- 2004, Phoenix Park, Korea, February 9-11, 2004.
-
-[POSIX] IEEE Std. 1003.1-2001 Standard for Information Technology --
- Portable Operating System Interface (POSIX). Open Group
- Technical Standard: Base Specifications, Issue 6, December
- 2001. ISO/IEC 9945:2002. http://www.opengroup.org/austin
-
-[RFC1536] Kumar, A., et. al., "DNS Implementation Errors and Suggested
- Fixes", RFC 1536, October 1993.
-
-[RFC1750] Eastlake, D., Crocker, S. and J. Schiller, "Randomness
- Recommendations for Security", RFC 1750, December 1994.
-
-[RFC2131] Droms, R., "Dynamic Host Configuration Protocol", RFC 2131,
- March 1997.
-
-[RFC2292] Stevens, W. and M. Thomas, "Advanced Sockets API for IPv6",
- RFC 2292, February 1998.
-
-[RFC2365] Meyer, D., "Administratively Scoped IP Multicast", BCP 23, RFC
- 2365, July 1998.
-
-[RFC2553] Gilligan, R., Thomson, S., Bound, J. and W. Stevens, "Basic
- Socket Interface Extensions for IPv6", RFC 2553, March 1999.
-
-[RFC2937] Smith, C., "The Name Service Search Option for DHCP", RFC
- 2937, September 2000.
-
-[RFC3315] Droms, R., et al., "Dynamic Host Configuration Protocol for
- IPv6 (DHCPv6)", RFC 3315, July 2003.
-
-[RFC3833] Atkins, D. and R. Austein, "Threat Analysis of the Domain Name
- System (DNS)", RFC 3833, August 2004.
-
-
-
-Aboba, Thaler & Esibov Standards Track [Page 27]
-
-
-
-
-
-INTERNET-DRAFT LLMNR 16 April 2006
-
-
-[RFC3927] Cheshire, S., Aboba, B. and E. Guttman, "Dynamic Configuration
- of Link-Local IPv4 Addresses", RFC 3927, October 2004.
-
-[RFC4033] Arends, R., Austein, R., Larson, M., Massey, D. and S. Rose,
- "DNS Security Introduction and Requirement", RFC 4033, March
- 2005.
-
-Acknowledgments
-
- This work builds upon original work done on multicast DNS by Bill
- Manning and Bill Woodcock. Bill Manning's work was funded under
- DARPA grant #F30602-99-1-0523. The authors gratefully acknowledge
- their contribution to the current specification. Constructive input
- has also been received from Mark Andrews, Rob Austein, Randy Bush,
- Stuart Cheshire, Ralph Droms, Robert Elz, James Gilroy, Olafur
- Gudmundsson, Andreas Gustafsson, Erik Guttman, Myron Hattig,
- Christian Huitema, Olaf Kolkman, Mika Liljeberg, Keith Moore,
- Tomohide Nagashima, Thomas Narten, Erik Nordmark, Markku Savela, Mike
- St. Johns, Sander Van-Valkenburg, and Brian Zill.
-
-Authors' Addresses
-
- Bernard Aboba
- Microsoft Corporation
- One Microsoft Way
- Redmond, WA 98052
-
- Phone: +1 425 706 6605
- EMail: bernarda@microsoft.com
-
- Dave Thaler
- Microsoft Corporation
- One Microsoft Way
- Redmond, WA 98052
-
- Phone: +1 425 703 8835
- EMail: dthaler@microsoft.com
-
- Levon Esibov
- Microsoft Corporation
- One Microsoft Way
- Redmond, WA 98052
-
- EMail: levone@microsoft.com
-
-
-
-
-
-
-
-Aboba, Thaler & Esibov Standards Track [Page 28]
-
-
-
-
-
-INTERNET-DRAFT LLMNR 16 April 2006
-
-
-Intellectual Property Statement
-
- The IETF takes no position regarding the validity or scope of any
- Intellectual Property Rights or other rights that might be claimed to
- pertain to the implementation or use of the technology described in
- this document or the extent to which any license under such rights
- might or might not be available; nor does it represent that it has
- made any independent effort to identify any such rights. Information
- on the procedures with respect to rights in RFC documents can be
- found in BCP 78 and BCP 79.
-
- Copies of IPR disclosures made to the IETF Secretariat and any
- assurances of licenses to be made available, or the result of an
- attempt made to obtain a general license or permission for the use of
- such proprietary rights by implementers or users of this
- specification can be obtained from the IETF on-line IPR repository at
- http://www.ietf.org/ipr.
-
- The IETF invites any interested party to bring to its attention any
- copyrights, patents or patent applications, or other proprietary
- rights that may cover technology that may be required to implement
- this standard. Please address the information to the IETF at ietf-
- ipr@ietf.org.
-
-Disclaimer of Validity
-
- This document and the information contained herein are provided on an
- "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS
- OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND THE INTERNET
- ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED,
- INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE
- INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED
- WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
-
-Copyright Statement
-
- Copyright (C) The Internet Society (2006). This document is subject
- to the rights, licenses and restrictions contained in BCP 78, and
- except as set forth therein, the authors retain all their rights.
-
-Acknowledgment
-
- Funding for the RFC Editor function is currently provided by the
- Internet Society.
-
-
-
-
-
-
-
-Aboba, Thaler & Esibov Standards Track [Page 29]
-
-
-
-
-
-INTERNET-DRAFT LLMNR 16 April 2006
-
-
-Open Issues
-
- Open issues with this specification are tracked on the following web
- site:
-
- http://www.drizzle.com/~aboba/DNSEXT/llmnrissues.html
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
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-Aboba, Thaler & Esibov Standards Track [Page 30]
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+++ /dev/null
-
-INTERNET-DRAFT DSA Information in the DNS
-OBSOLETES: RFC 2536 Donald E. Eastlake 3rd
- Motorola Laboratories
-Expires: September 2006 March 2006
-
-
- DSA Keying and Signature Information in the DNS
- --- ------ --- --------- ----------- -- --- ---
- <draft-ietf-dnsext-rfc2536bis-dsa-07.txt>
- Donald E. Eastlake 3rd
-
-
-Status of This Document
-
- By submitting this Internet-Draft, each author represents that any
- applicable patent or other IPR claims of which he or she is aware
- have been or will be disclosed, and any of which he or she becomes
- aware will be disclosed, in accordance with Section 6 of BCP 79.
-
- Distribution of this document is unlimited. Comments should be sent
- to the DNS extensions working group mailing list
- <namedroppers@ops.ietf.org>.
-
- Internet-Drafts are working documents of the Internet Engineering
- Task Force (IETF), its areas, and its working groups. Note that
- other groups may also distribute working documents as Internet-
- Drafts.
-
- Internet-Drafts are draft documents valid for a maximum of six months
- and may be updated, replaced, or obsoleted by other documents at any
- time. It is inappropriate to use Internet-Drafts as reference
- material or to cite them other than as "work in progress."
-
- The list of current Internet-Drafts can be accessed at
- http://www.ietf.org/1id-abstracts.html
-
- The list of Internet-Draft Shadow Directories can be accessed at
- http://www.ietf.org/shadow.html
-
-
-
-Abstract
-
- The standard method of encoding US Government Digital Signature
- Algorithm keying and signature information for use in the Domain Name
- System is specified.
-
-
-
-
-
-
-
-
-
-D. Eastlake 3rd [Page 1]
-\f
-
-INTERNET-DRAFT DSA Information in the DNS
-
-
-Table of Contents
-
- Status of This Document....................................1
- Abstract...................................................1
-
- Table of Contents..........................................2
-
- 1. Introduction............................................3
- 2. DSA Keying Information..................................3
- 3. DSA Signature Information...............................4
- 4. Performance Considerations..............................4
- 5. Security Considerations.................................5
- 6. IANA Considerations.....................................5
- Copyright, Disclaimer, and Additional IPR Provisions.......5
-
- Normative References.......................................7
- Informative References.....................................7
-
- Author's Address...........................................8
- Expiration and File Name...................................8
-
-
-
-
-
-
-
-
-
-
-
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-D. Eastlake 3rd [Page 2]
-\f
-
-INTERNET-DRAFT DSA Information in the DNS
-
-
-1. Introduction
-
- The Domain Name System (DNS) is the global hierarchical replicated
- distributed database system for Internet addressing, mail proxy, and
- other information [RFC 1034, 1035]. The DNS has been extended to
- include digital signatures and cryptographic keys as described in
- [RFC 4033, 4034, 4035] and additional work is underway which would
- require the storage of keying and signature information in the DNS.
-
- This document describes how to encode US Government Digital Signature
- Algorithm (DSA) keys and signatures in the DNS. Familiarity with the
- US Digital Signature Algorithm is assumed [FIPS 186-2, Schneier].
-
-
-
-2. DSA Keying Information
-
- When DSA public keys are stored in the DNS, the structure of the
- relevant part of the RDATA part of the RR being used is the fields
- listed below in the order given.
-
- The period of key validity is not included in this data but is
- indicated separately, for example by an RR such as RRSIG which signs
- and authenticates the RR containing the keying information.
-
- Field Size
- ----- ----
- T 1 octet
- Q 20 octets
- P 64 + T*8 octets
- G 64 + T*8 octets
- Y 64 + T*8 octets
-
- As described in [FIPS 186-2] and [Schneier], T is a key size
- parameter chosen such that 0 <= T <= 8. (The meaning if the T octet
- is greater than 8 is reserved and the remainder of the data may have
- a different format in that case.) Q is a prime number selected at
- key generation time such that 2**159 < Q < 2**160. Thus Q is always
- 20 octets long and, as with all other fields, is stored in "big-
- endian" network order. P, G, and Y are calculated as directed by the
- [FIPS 186-2] key generation algorithm [Schneier]. P is in the range
- 2**(511+64T) < P < 2**(512+64T) and thus is 64 + 8*T octets long. G
- and Y are quantities modulo P and so can be up to the same length as
- P and are allocated fixed size fields with the same number of octets
- as P.
-
- During the key generation process, a random number X must be
- generated such that 1 <= X <= Q-1. X is the private key and is used
- in the final step of public key generation where Y is computed as
-
-
-
-D. Eastlake 3rd [Page 3]
-\f
-
-INTERNET-DRAFT DSA Information in the DNS
-
-
- Y = G**X mod P
-
-
-
-3. DSA Signature Information
-
- The portion of the RDATA area used for US Digital Signature Algorithm
- signature information is shown below with fields in the order they
- are listed and the contents of each multi-octet field in "big-endian"
- network order.
-
- Field Size
- ----- ----
- T 1 octet
- R 20 octets
- S 20 octets
-
- First, the data signed must be determined. Then the following steps
- are taken, as specified in [FIPS 186-2], where Q, P, G, and Y are as
- specified in the public key [Schneier]:
-
- hash = SHA-1 ( data )
-
- Generate a random K such that 0 < K < Q.
-
- R = ( G**K mod P ) mod Q
-
- S = ( K**(-1) * (hash + X*R) ) mod Q
-
- For information on the SHA-1 hash function see [FIPS 180-2] and [RFC
- 3174].
-
- Since Q is 160 bits long, R and S can not be larger than 20 octets,
- which is the space allocated.
-
- T is copied from the public key. It is not logically necessary in
- the SIG but is present so that values of T > 8 can more conveniently
- be used as an escape for extended versions of DSA or other algorithms
- as later standardized.
-
-
-
-4. Performance Considerations
-
- General signature generation speeds are roughly the same for RSA [RFC
- 3110] and DSA. With sufficient pre-computation, signature generation
- with DSA is faster than RSA. Key generation is also faster for DSA.
- However, signature verification is an order of magnitude slower than
- RSA when the RSA public exponent is chosen to be small, as is
- recommended for some applications.
-
-
-D. Eastlake 3rd [Page 4]
-\f
-
-INTERNET-DRAFT DSA Information in the DNS
-
-
- Current DNS implementations are optimized for small transfers,
- typically less than 512 bytes including DNS overhead. Larger
- transfers will perform correctly and extensions have been
- standardized [RFC 2671] to make larger transfers more efficient, it
- is still advisable at this time to make reasonable efforts to
- minimize the size of RR sets containing keying and/or signature
- inforamtion consistent with adequate security.
-
-
-
-5. Security Considerations
-
- Keys retrieved from the DNS should not be trusted unless (1) they
- have been securely obtained from a secure resolver or independently
- verified by the user and (2) this secure resolver and secure
- obtainment or independent verification conform to security policies
- acceptable to the user. As with all cryptographic algorithms,
- evaluating the necessary strength of the key is essential and
- dependent on local policy.
-
- The key size limitation of a maximum of 1024 bits ( T = 8 ) in the
- current DSA standard may limit the security of DSA. For particular
- applications, implementors are encouraged to consider the range of
- available algorithms and key sizes.
-
- DSA assumes the ability to frequently generate high quality random
- numbers. See [random] for guidance. DSA is designed so that if
- biased rather than random numbers are used, high bandwidth covert
- channels are possible. See [Schneier] and more recent research. The
- leakage of an entire DSA private key in only two DSA signatures has
- been demonstrated. DSA provides security only if trusted
- implementations, including trusted random number generation, are
- used.
-
-
-
-6. IANA Considerations
-
- Allocation of meaning to values of the T parameter that are not
- defined herein (i.e., > 8 ) requires an IETF standards actions. It
- is intended that values unallocated herein be used to cover future
- extensions of the DSS standard.
-
-
-
-Copyright, Disclaimer, and Additional IPR Provisions
-
- Copyright (C) The Internet Society (2006). This document is subject to
- the rights, licenses and restrictions contained in BCP 78, and except
- as set forth therein, the authors retain all their rights.
-
-
-D. Eastlake 3rd [Page 5]
-\f
-
-INTERNET-DRAFT DSA Information in the DNS
-
-
- This document and the information contained herein are provided on an
- "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS
- OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND THE INTERNET
- ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED,
- INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE
- INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED
- WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
-
- The IETF takes no position regarding the validity or scope of any
- Intellectual Property Rights or other rights that might be claimed to
- pertain to the implementation or use of the technology described in
- this document or the extent to which any license under such rights
- might or might not be available; nor does it represent that it has
- made any independent effort to identify any such rights. Information
- on the procedures with respect to rights in RFC documents can be
- found in BCP 78 and BCP 79.
-
- Copies of IPR disclosures made to the IETF Secretariat and any
- assurances of licenses to be made available, or the result of an
- attempt made to obtain a general license or permission for the use of
- such proprietary rights by implementers or users of this
- specification can be obtained from the IETF on-line IPR repository at
- http://www.ietf.org/ipr.
-
- The IETF invites any interested party to bring to its attention any
- copyrights, patents or patent applications, or other proprietary
- rights that may cover technology that may be required to implement
- this standard. Please address the information to the IETF at ietf-
- ipr@ietf.org.
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-D. Eastlake 3rd [Page 6]
-\f
-
-INTERNET-DRAFT DSA Information in the DNS
-
-
-Normative References
-
- [FIPS 186-2] - U.S. Federal Information Processing Standard: Digital
- Signature Standard, 27 January 2000.
-
- [RFC 4034] - Arends, R., Austein, R., Larson, M., Massey, D., and S.
- Rose, "Resource Records for the DNS Security Extensions", RFC 4034,
- March 2005.
-
-
-
-Informative References
-
- [RFC 1034] - "Domain names - concepts and facilities", P.
- Mockapetris, 11/01/1987.
-
- [RFC 1035] - "Domain names - implementation and specification", P.
- Mockapetris, 11/01/1987.
-
- [RFC 2671] - "Extension Mechanisms for DNS (EDNS0)", P. Vixie, August
- 1999.
-
- [RFC 3110] - "RSA/SHA-1 SIGs and RSA KEYs in the Domain Name System
- (DNS)", D. Eastlake 3rd. May 2001.
-
- [RFC 3174] - "US Secure Hash Algorithm 1 (SHA1)", D. Eastlake, P.
- Jones, September 2001.
-
- [RFC 4033] - Arends, R., Austein, R., Larson, M., Massey, D., and S.
- Rose, "DNS Security Introduction and Requirements", RFC 4033, March
- 2005.
-
- [RFC 4035] - Arends, R., Austein, R., Larson, M., Massey, D., and S.
- Rose, "Protocol Modifications for the DNS Security Extensions", RFC
- 4035, March 2005.
-
- [RFC 4086] - Eastlake, D., 3rd, Schiller, J., and S. Crocker,
- "Randomness Requirements for Security", BCP 106, RFC 4086, June 2005.
-
- [Schneier] - "Applied Cryptography Second Edition: protocols,
- algorithms, and source code in C" (second edition), Bruce Schneier,
- 1996, John Wiley and Sons, ISBN 0-471-11709-9.
-
-
-
-
-
-
-
-
-
-
-D. Eastlake 3rd [Page 7]
-\f
-
-INTERNET-DRAFT DSA Information in the DNS
-
-
-Author's Address
-
- Donald E. Eastlake 3rd
- Motorola Labortories
- 155 Beaver Street
- Milford, MA 01757 USA
-
- Telephone: +1-508-786-7554(w)
- EMail: Donald.Eastlake@motorola.com
-
-
-
-Expiration and File Name
-
- This draft expires in September 2006.
-
- Its file name is draft-ietf-dnsext-rfc2536bis-dsa-07.txt.
-
-
-
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-D. Eastlake 3rd [Page 8]
-\f
+++ /dev/null
-
-INTERNET-DRAFT Diffie-Hellman Information in the DNS
-OBSOLETES: RFC 2539 Donald E. Eastlake 3rd
- Motorola Laboratories
-Expires: September 2006 March 2006
-
-
-
-
- Storage of Diffie-Hellman Keying Information in the DNS
- ------- -- -------------- ------ ----------- -- --- ---
- <draft-ietf-dnsext-rfc2539bis-dhk-07.txt>
-
-
-
-Status of This Document
-
- By submitting this Internet-Draft, each author represents that any
- applicable patent or other IPR claims of which he or she is aware
- have been or will be disclosed, and any of which he or she becomes
- aware will be disclosed, in accordance with Section 6 of BCP 79.
-
- Distribution of this document is unlimited. Comments should be sent
- to the DNS extensions working group mailing list
- <namedroppers@ops.ietf.org>.
-
- Internet-Drafts are working documents of the Internet Engineering
- Task Force (IETF), its areas, and its working groups. Note that
- other groups may also distribute working documents as Internet-
- Drafts.
-
- Internet-Drafts are draft documents valid for a maximum of six months
- and may be updated, replaced, or obsoleted by other documents at any
- time. It is inappropriate to use Internet-Drafts as reference
- material or to cite them other than as "work in progress."
-
- The list of current Internet-Drafts can be accessed at
- http://www.ietf.org/1id-abstracts.html
-
- The list of Internet-Draft Shadow Directories can be accessed at
- http://www.ietf.org/shadow.html
-
-
-Abstract
-
- The standard method for encoding Diffie-Hellman keys in the Domain
- Name System is specified.
-
-
-
-
-
-
-
-
-
-D. Eastlake 3rd [Page 1]
-\f
-
-INTERNET-DRAFT Diffie-Hellman Information in the DNS
-
-
-Acknowledgements
-
- Part of the format for Diffie-Hellman keys and the description
- thereof was taken from a work in progress by Ashar Aziz, Tom Markson,
- and Hemma Prafullchandra. In addition, the following persons
- provided useful comments that were incorporated into the predecessor
- of this document: Ran Atkinson, Thomas Narten.
-
-
-
-Table of Contents
-
- Status of This Document....................................1
- Abstract...................................................1
-
- Acknowledgements...........................................2
- Table of Contents..........................................2
-
- 1. Introduction............................................3
- 1.1 About This Document....................................3
- 1.2 About Diffie-Hellman...................................3
- 2. Encoding Diffie-Hellman Keying Information..............4
- 3. Performance Considerations..............................5
- 4. IANA Considerations.....................................5
- 5. Security Considerations.................................5
- Copyright, Disclaimer, and Additional IPR Provisions.......5
-
- Normative References.......................................7
- Informative Refences.......................................7
-
- Author's Address...........................................8
- Expiration and File Name...................................8
-
- Appendix A: Well known prime/generator pairs...............9
- A.1. Well-Known Group 1: A 768 bit prime..................9
- A.2. Well-Known Group 2: A 1024 bit prime.................9
- A.3. Well-Known Group 3: A 1536 bit prime................10
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-D. Eastlake 3rd [Page 2]
-\f
-
-INTERNET-DRAFT Diffie-Hellman Information in the DNS
-
-
-1. Introduction
-
- The Domain Name System (DNS) is the global hierarchical replicated
- distributed database system for Internet addressing, mail proxy, and
- similar information [RFC 1034, 1035]. The DNS has been extended to
- include digital signatures and cryptographic keys as described in
- [RFC 4033, 4034, 4035] and additonal work is underway which would use
- the storage of keying information in the DNS.
-
-
-
-1.1 About This Document
-
- This document describes how to store Diffie-Hellman keys in the DNS.
- Familiarity with the Diffie-Hellman key exchange algorithm is assumed
- [Schneier, RFC 2631].
-
- The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
- "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
- document are to be interpreted as described in RFC 2119.
-
-
-
-1.2 About Diffie-Hellman
-
- Diffie-Hellman requires two parties to interact to derive keying
- information which can then be used for authentication. Thus Diffie-
- Hellman is inherently a key agreement algorithm. As a result, no
- format is defined for Diffie-Hellman "signature information". For
- example, assume that two parties have local secrets "i" and "j".
- Assume they each respectively calculate X and Y as follows:
-
- X = g**i ( mod p )
-
- Y = g**j ( mod p )
-
- They exchange these quantities and then each calculates a Z as
- follows:
-
- Zi = Y**i ( mod p )
-
- Zj = X**j ( mod p )
-
- Zi and Zj will both be equal to g**(i*j)(mod p) and will be a shared
- secret between the two parties that an adversary who does not know i
- or j will not be able to learn from the exchanged messages (unless
- the adversary can derive i or j by performing a discrete logarithm
- mod p which is hard for strong p and g).
-
- The private key for each party is their secret i (or j). The public
-
-
-D. Eastlake 3rd [Page 3]
-\f
-
-INTERNET-DRAFT Diffie-Hellman Information in the DNS
-
-
- key is the pair p and g, which is the same for both parties, and
- their individual X (or Y).
-
- For further information about Diffie-Hellman and precautions to take
- in deciding on a p and g, see [RFC 2631].
-
-
-
-2. Encoding Diffie-Hellman Keying Information
-
- When Diffie-Hellman keys appear within the RDATA portion of a RR,
- they are encoded as shown below.
-
- The period of key validity is not included in this data but is
- indicated separately, for example by an RR such as RRSIG which signs
- and authenticates the RR containing the keying information.
-
- 1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 2 3 3
- 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
- +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
- | KEY flags | protocol | algorithm=2 |
- +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
- | prime length (or flag) | prime (p) (or special) /
- +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
- / prime (p) (variable length) | generator length |
- +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
- | generator (g) (variable length) |
- +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
- | public value length | public value (variable length)/
- +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
- / public value (g^i mod p) (variable length) |
- +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
-
- Prime length is the length of the Diffie-Hellman prime (p) in bytes
- if it is 16 or greater. Prime contains the binary representation of
- the Diffie-Hellman prime with most significant byte first (i.e., in
- network order). If "prime length" field is 1 or 2, then the "prime"
- field is actually an unsigned index into a table of 65,536
- prime/generator pairs and the generator length SHOULD be zero. See
- Appedix A for defined table entries and Section 4 for information on
- allocating additional table entries. The meaning of a zero or 3
- through 15 value for "prime length" is reserved.
-
- Generator length is the length of the generator (g) in bytes.
- Generator is the binary representation of generator with most
- significant byte first. PublicValueLen is the Length of the Public
- Value (g**i (mod p)) in bytes. PublicValue is the binary
- representation of the DH public value with most significant byte
- first.
-
-
-
-D. Eastlake 3rd [Page 4]
-\f
-
-INTERNET-DRAFT Diffie-Hellman Information in the DNS
-
-
-3. Performance Considerations
-
- Current DNS implementations are optimized for small transfers,
- typically less than 512 bytes including DNS overhead. Larger
- transfers will perform correctly and extensions have been
- standardized [RFC 2671] to make larger transfers more efficient. But
- it is still advisable at this time to make reasonable efforts to
- minimize the size of RR sets containing keying information consistent
- with adequate security.
-
-
-
-4. IANA Considerations
-
- Assignment of meaning to Prime Lengths of 0 and 3 through 15 requires
- an IETF consensus as defined in [RFC 2434].
-
- Well known prime/generator pairs number 0x0000 through 0x07FF can
- only be assigned by an IETF standards action. [RFC 2539], the
- Proposed Standard predecessor of this document, assigned 0x0001
- through 0x0002. This document additionally assigns 0x0003. Pairs
- number 0s0800 through 0xBFFF can be assigned based on RFC
- documentation. Pairs number 0xC000 through 0xFFFF are available for
- private use and are not centrally coordinated. Use of such private
- pairs outside of a closed environment may result in conflicts and/or
- security failures.
-
-
-
-5. Security Considerations
-
- Keying information retrieved from the DNS should not be trusted
- unless (1) it has been securely obtained from a secure resolver or
- independently verified by the user and (2) this secure resolver and
- secure obtainment or independent verification conform to security
- policies acceptable to the user. As with all cryptographic
- algorithms, evaluating the necessary strength of the key is important
- and dependent on security policy.
-
- In addition, the usual Diffie-Hellman key strength considerations
- apply. (p-1)/2 SHOULD also be prime, g SHOULD be primitive mod p, p
- SHOULD be "large", etc. See [RFC 2631, Schneier].
-
-
-
-Copyright, Disclaimer, and Additional IPR Provisions
-
- Copyright (C) The Internet Society (2006). This document is subject to
- the rights, licenses and restrictions contained in BCP 78, and except
- as set forth therein, the authors retain all their rights.
-
-
-D. Eastlake 3rd [Page 5]
-\f
-
-INTERNET-DRAFT Diffie-Hellman Information in the DNS
-
-
- This document and the information contained herein are provided on an
- "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS
- OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND THE INTERNET
- ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED,
- INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE
- INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED
- WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
-
- The IETF takes no position regarding the validity or scope of any
- Intellectual Property Rights or other rights that might be claimed to
- pertain to the implementation or use of the technology described in
- this document or the extent to which any license under such rights
- might or might not be available; nor does it represent that it has
- made any independent effort to identify any such rights. Information
- on the procedures with respect to rights in RFC documents can be
- found in BCP 78 and BCP 79.
-
- Copies of IPR disclosures made to the IETF Secretariat and any
- assurances of licenses to be made available, or the result of an
- attempt made to obtain a general license or permission for the use of
- such proprietary rights by implementers or users of this
- specification can be obtained from the IETF on-line IPR repository at
- http://www.ietf.org/ipr.
-
- The IETF invites any interested party to bring to its attention any
- copyrights, patents or patent applications, or other proprietary
- rights that may cover technology that may be required to implement
- this standard. Please address the information to the IETF at ietf-
- ipr@ietf.org.
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-D. Eastlake 3rd [Page 6]
-\f
-
-INTERNET-DRAFT Diffie-Hellman Information in the DNS
-
-
-Normative References
-
- [RFC 2119] - Bradner, S., "Key words for use in RFCs to Indicate
- Requirement Levels", BCP 14, RFC 2119, March 1997.
-
- [RFC 2434] - "Guidelines for Writing an IANA Considerations Section
- in RFCs", T. Narten, H. Alvestrand, October 1998.
-
- [RFC 2631] - "Diffie-Hellman Key Agreement Method", E. Rescorla, June
- 1999.
-
- [RFC 4034] - Arends, R., Austein, R., Larson, M., Massey, D., and S.
- Rose, "Resource Records for the DNS Security Extensions", RFC 4034,
- March 2005.
-
-
-
-Informative Refences
-
- [RFC 1034] - "Domain names - concepts and facilities", P.
- Mockapetris, November 1987.
-
- [RFC 1035] - "Domain names - implementation and specification", P.
- Mockapetris, November 1987.
-
- [RFC 2539] - "Storage of Diffie-Hellman Keys in the Domain Name
- System (DNS)", D. Eastlake, March 1999, obsoleted by this RFC.
-
- [RFC 2671] - "Extension Mechanisms for DNS (EDNS0)", P. Vixie, August
- 1999.
-
- [RFC 4033] - Arends, R., Austein, R., Larson, M., Massey, D., and S.
- Rose, "DNS Security Introduction and Requirements", RFC 4033, March
- 2005.
-
- [RFC 4035] - Arends, R., Austein, R., Larson, M., Massey, D., and S.
- Rose, "Protocol Modifications for the DNS Security Extensions", RFC
- 4035, March 2005.
-
- [Schneier] - Bruce Schneier, "Applied Cryptography: Protocols,
- Algorithms, and Source Code in C" (Second Edition), 1996, John Wiley
- and Sons.
-
-
-
-
-
-
-
-
-
-
-D. Eastlake 3rd [Page 7]
-\f
-
-INTERNET-DRAFT Diffie-Hellman Information in the DNS
-
-
-Author's Address
-
- Donald E. Eastlake 3rd
- Motorola Laboratories
- 155 Beaver Street
- Milford, MA 01757 USA
-
- Telephone: +1-508-786-7554
- EMail: Donald.Eastlake@motorola.com
-
-
-
-Expiration and File Name
-
- This draft expires in September 2006.
-
- Its file name is draft-ietf-dnsext-rfc2539bis-dhk-07.txt.
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
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-
-
-D. Eastlake 3rd [Page 8]
-\f
-
-INTERNET-DRAFT Diffie-Hellman Information in the DNS
-
-
-Appendix A: Well known prime/generator pairs
-
- These numbers are copied from the IPSEC effort where the derivation
- of these values is more fully explained and additional information is
- available. Richard Schroeppel performed all the mathematical and
- computational work for this appendix.
-
-
-
-A.1. Well-Known Group 1: A 768 bit prime
-
- The prime is 2^768 - 2^704 - 1 + 2^64 * { [2^638 pi] + 149686 }. Its
- decimal value is
- 155251809230070893513091813125848175563133404943451431320235
- 119490296623994910210725866945387659164244291000768028886422
- 915080371891804634263272761303128298374438082089019628850917
- 0691316593175367469551763119843371637221007210577919
-
- Prime modulus: Length (32 bit words): 24, Data (hex):
- FFFFFFFF FFFFFFFF C90FDAA2 2168C234 C4C6628B 80DC1CD1
- 29024E08 8A67CC74 020BBEA6 3B139B22 514A0879 8E3404DD
- EF9519B3 CD3A431B 302B0A6D F25F1437 4FE1356D 6D51C245
- E485B576 625E7EC6 F44C42E9 A63A3620 FFFFFFFF FFFFFFFF
-
- Generator: Length (32 bit words): 1, Data (hex): 2
-
-
-
-A.2. Well-Known Group 2: A 1024 bit prime
-
- The prime is 2^1024 - 2^960 - 1 + 2^64 * { [2^894 pi] + 129093 }.
- Its decimal value is
- 179769313486231590770839156793787453197860296048756011706444
- 423684197180216158519368947833795864925541502180565485980503
- 646440548199239100050792877003355816639229553136239076508735
- 759914822574862575007425302077447712589550957937778424442426
- 617334727629299387668709205606050270810842907692932019128194
- 467627007
-
- Prime modulus: Length (32 bit words): 32, Data (hex):
- FFFFFFFF FFFFFFFF C90FDAA2 2168C234 C4C6628B 80DC1CD1
- 29024E08 8A67CC74 020BBEA6 3B139B22 514A0879 8E3404DD
- EF9519B3 CD3A431B 302B0A6D F25F1437 4FE1356D 6D51C245
- E485B576 625E7EC6 F44C42E9 A637ED6B 0BFF5CB6 F406B7ED
- EE386BFB 5A899FA5 AE9F2411 7C4B1FE6 49286651 ECE65381
- FFFFFFFF FFFFFFFF
-
- Generator: Length (32 bit words): 1, Data (hex): 2
-
-
-
-
-D. Eastlake 3rd [Page 9]
-\f
-
-INTERNET-DRAFT Diffie-Hellman Information in the DNS
-
-
-A.3. Well-Known Group 3: A 1536 bit prime
-
- The prime is 2^1536 - 2^1472 - 1 + 2^64 * { [2^1406 pi] + 741804 }.
- Its decimal value is
- 241031242692103258855207602219756607485695054850245994265411
- 694195810883168261222889009385826134161467322714147790401219
- 650364895705058263194273070680500922306273474534107340669624
- 601458936165977404102716924945320037872943417032584377865919
- 814376319377685986952408894019557734611984354530154704374720
- 774996976375008430892633929555996888245787241299381012913029
- 459299994792636526405928464720973038494721168143446471443848
- 8520940127459844288859336526896320919633919
-
- Prime modulus Length (32 bit words): 48, Data (hex):
- FFFFFFFF FFFFFFFF C90FDAA2 2168C234 C4C6628B 80DC1CD1
- 29024E08 8A67CC74 020BBEA6 3B139B22 514A0879 8E3404DD
- EF9519B3 CD3A431B 302B0A6D F25F1437 4FE1356D 6D51C245
- E485B576 625E7EC6 F44C42E9 A637ED6B 0BFF5CB6 F406B7ED
- EE386BFB 5A899FA5 AE9F2411 7C4B1FE6 49286651 ECE45B3D
- C2007CB8 A163BF05 98DA4836 1C55D39A 69163FA8 FD24CF5F
- 83655D23 DCA3AD96 1C62F356 208552BB 9ED52907 7096966D
- 670C354E 4ABC9804 F1746C08 CA237327 FFFFFFFF FFFFFFFF
-
- Generator: Length (32 bit words): 1, Data (hex): 2
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-D. Eastlake 3rd [Page 10]
-\f
+++ /dev/null
-
-
-
-
-
-
- DNSOP Working Group Paul Vixie, ISC
- INTERNET-DRAFT Akira Kato, WIDE
- <draft-ietf-dnsop-respsize-06.txt> August 2006
-
- DNS Referral Response Size Issues
-
- Status of this Memo
- By submitting this Internet-Draft, each author represents that any
- applicable patent or other IPR claims of which he or she is aware
- have been or will be disclosed, and any of which he or she becomes
- aware will be disclosed, in accordance with Section 6 of BCP 79.
-
- Internet-Drafts are working documents of the Internet Engineering
- Task Force (IETF), its areas, and its working groups. Note that
- other groups may also distribute working documents as Internet-
- Drafts.
-
- Internet-Drafts are draft documents valid for a maximum of six months
- and may be updated, replaced, or obsoleted by other documents at any
- time. It is inappropriate to use Internet-Drafts as reference
- material or to cite them other than as "work in progress."
-
- The list of current Internet-Drafts can be accessed at
- http://www.ietf.org/ietf/1id-abstracts.txt
-
- The list of Internet-Draft Shadow Directories can be accessed at
- http://www.ietf.org/shadow.html.
-
- Copyright Notice
-
- Copyright (C) The Internet Society (2006). All Rights Reserved.
-
-
-
-
- Abstract
-
- With a mandated default minimum maximum message size of 512 octets,
- the DNS protocol presents some special problems for zones wishing to
- expose a moderate or high number of authority servers (NS RRs). This
- document explains the operational issues caused by, or related to
- this response size limit, and suggests ways to optimize the use of
- this limited space. Guidance is offered to DNS server implementors
- and to DNS zone operators.
-
-
-
-
- Expires January 2007 [Page 1]
-\f
- INTERNET-DRAFT August 2006 RESPSIZE
-
-
- 1 - Introduction and Overview
-
- 1.1. The DNS standard (see [RFC1035 4.2.1]) limits message size to 512
- octets. Even though this limitation was due to the required minimum IP
- reassembly limit for IPv4, it became a hard DNS protocol limit and is
- not implicitly relaxed by changes in transport, for example to IPv6.
-
- 1.2. The EDNS0 protocol extension (see [RFC2671 2.3, 4.5]) permits
- larger responses by mutual agreement of the requester and responder.
- The 512 octet message size limit will remain in practical effect until
- there is widespread deployment of EDNS0 in DNS resolvers on the
- Internet.
-
- 1.3. Since DNS responses include a copy of the request, the space
- available for response data is somewhat less than the full 512 octets.
- Negative responses are quite small, but for positive and delegation
- responses, every octet must be carefully and sparingly allocated. This
- document specifically addresses delegation response sizes.
-
- 2 - Delegation Details
-
- 2.1. RELEVANT PROTOCOL ELEMENTS
-
- 2.1.1. A delegation response will include the following elements:
-
- Header Section: fixed length (12 octets)
- Question Section: original query (name, class, type)
- Answer Section: empty, or a CNAME/DNAME chain
- Authority Section: NS RRset (nameserver names)
- Additional Section: A and AAAA RRsets (nameserver addresses)
-
- 2.1.2. If the total response size exceeds 512 octets, and if the data
- that does not fit was "required", then the TC bit will be set
- (indicating truncation). This will usually cause the requester to retry
- using TCP, depending on what information was desired and what
- information was omitted. For example, truncation in the authority
- section is of no interest to a stub resolver who only plans to consume
- the answer section. If a retry using TCP is needed, the total cost of
- the transaction is much higher. See [RFC1123 6.1.3.2] for details on
- the requirement that UDP be attempted before falling back to TCP.
-
- 2.1.3. RRsets are never sent partially unless TC bit set to indicate
- truncation. When TC bit is set, the final apparent RRset in the final
- non-empty section must be considered "possibly damaged" (see [RFC1035
- 6.2], [RFC2181 9]).
-
-
-
- Expires January 2007 [Page 2]
-\f
- INTERNET-DRAFT August 2006 RESPSIZE
-
-
- 2.1.4. With or without truncation, the glue present in the additional
- data section should be considered "possibly incomplete", and requesters
- should be prepared to re-query for any damaged or missing RRsets. Note
- that truncation of the additional data section might not be signalled
- via the TC bit since additional data is often optional (see discussion
- in [RFC4472 B]).
-
- 2.1.5. DNS label compression allows a domain name to be instantiated
- only once per DNS message, and then referenced with a two-octet
- "pointer" from other locations in that same DNS message (see [RFC1035
- 4.1.4]). If all nameserver names in a message share a common parent
- (for example, all ending in ".ROOT-SERVERS.NET"), then more space will
- be available for incompressable data (such as nameserver addresses).
-
- 2.1.6. The query name can be as long as 255 octets of network data. In
- this worst case scenario, the question section will be 259 octets in
- size, which would leave only 240 octets for the authority and additional
- sections (after deducting 12 octets for the fixed length header.)
-
- 2.2. ADVICE TO ZONE OWNERS
-
- 2.2.1. Average and maximum question section sizes can be predicted by
- the zone owner, since they will know what names actually exist, and can
- measure which ones are queried for most often. Note that if the zone
- contains any wildcards, it is possible for maximum length queries to
- require positive responses, but that it is reasonable to expect
- truncation and TCP retry in that case. For cost and performance
- reasons, the majority of requests should be satisfied without truncation
- or TCP retry.
-
- 2.2.2. Some queries to non-existing names can be large, but this is not
- a problem because negative responses need not contain any answer,
- authority or additional records. See [RFC2308 2.1] for more information
- about the format of negative responses.
-
- 2.2.3. The minimum useful number of name servers is two, for redundancy
- (see [RFC1034 4.1]). A zone's name servers should be reachable by all
- IP transport protocols (e.g., IPv4 and IPv6) in common use.
-
- 2.2.4. The best case is no truncation at all. This is because many
- requesters will retry using TCP immediately, or will automatically re-
- query for RRsets that are possibly truncated, without considering
- whether the omitted data was actually necessary.
-
-
-
-
-
- Expires January 2007 [Page 3]
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- INTERNET-DRAFT August 2006 RESPSIZE
-
-
- 2.3. ADVICE TO SERVER IMPLEMENTORS
-
- 2.3.1. In case of multi-homed name servers, it is advantageous to
- include an address record from each of several name servers before
- including several address records for any one name server. If address
- records for more than one transport (for example, A and AAAA) are
- available, then it is advantageous to include records of both types
- early on, before the message is full.
-
- 2.3.2. Each added NS RR for a zone will add 12 fixed octets (name, type,
- class, ttl, and rdlen) plus 2 to 255 variable octets (for the NSDNAME).
- Each A RR will require 16 octets, and each AAAA RR will require 28
- octets.
-
- 2.3.3. While DNS distinguishes between necessary and optional resource
- records, this distinction is according to protocol elements necessary to
- signify facts, and takes no official notice of protocol content
- necessary to ensure correct operation. For example, a nameserver name
- that is in or below the zone cut being described by a delegation is
- "necessary content," since there is no way to reach that zone unless the
- parent zone's delegation includes "glue records" describing that name
- server's addresses.
-
- 2.3.4. It is also necessary to distinguish between "explicit truncation"
- where a message could not contain enough records to convey its intended
- meaning, and so the TC bit has been set, and "silent truncation", where
- the message was not large enough to contain some records which were "not
- required", and so the TC bit was not set.
-
- 2.3.5. A delegation response should prioritize glue records as follows.
-
- first
- All glue RRsets for one name server whose name is in or below the
- zone being delegated, or which has multiple address RRsets (currently
- A and AAAA), or preferably both;
-
- second
- Alternate between adding all glue RRsets for any name servers whose
- names are in or below the zone being delegated, and all glue RRsets
- for any name servers who have multiple address RRsets (currently A
- and AAAA);
-
- thence
- All other glue RRsets, in any order.
-
-
-
-
- Expires January 2007 [Page 4]
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- INTERNET-DRAFT August 2006 RESPSIZE
-
-
- Whenever there are multiple candidates for a position in this priority
- scheme, one should be chosen on a round-robin or fully random basis.
-
- The goal of this priority scheme is to offer "necessary" glue first,
- avoiding silent truncation for this glue if possible.
-
- 2.3.6. If any "necessary content" is silently truncated, then it is
- advisable that the TC bit be set in order to force a TCP retry, rather
- than have the zone be unreachable. Note that a parent server's proper
- response to a query for in-child glue or below-child glue is a referral
- rather than an answer, and that this referral MUST be able to contain
- the in-child or below-child glue, and that in outlying cases, only EDNS
- or TCP will be large enough to contain that data.
-
- 3 - Analysis
-
- 3.1. An instrumented protocol trace of a best case delegation response
- follows. Note that 13 servers are named, and 13 addresses are given.
- This query was artificially designed to exactly reach the 512 octet
- limit.
-
- ;; flags: qr rd; QUERY: 1, ANS: 0, AUTH: 13, ADDIT: 13
- ;; QUERY SECTION:
- ;; [23456789.123456789.123456789.\
- 123456789.123456789.123456789.com A IN] ;; @80
-
- ;; AUTHORITY SECTION:
- com. 86400 NS E.GTLD-SERVERS.NET. ;; @112
- com. 86400 NS F.GTLD-SERVERS.NET. ;; @128
- com. 86400 NS G.GTLD-SERVERS.NET. ;; @144
- com. 86400 NS H.GTLD-SERVERS.NET. ;; @160
- com. 86400 NS I.GTLD-SERVERS.NET. ;; @176
- com. 86400 NS J.GTLD-SERVERS.NET. ;; @192
- com. 86400 NS K.GTLD-SERVERS.NET. ;; @208
- com. 86400 NS L.GTLD-SERVERS.NET. ;; @224
- com. 86400 NS M.GTLD-SERVERS.NET. ;; @240
- com. 86400 NS A.GTLD-SERVERS.NET. ;; @256
- com. 86400 NS B.GTLD-SERVERS.NET. ;; @272
- com. 86400 NS C.GTLD-SERVERS.NET. ;; @288
- com. 86400 NS D.GTLD-SERVERS.NET. ;; @304
-
-
-
-
-
-
-
-
- Expires January 2007 [Page 5]
-\f
- INTERNET-DRAFT August 2006 RESPSIZE
-
-
- ;; ADDITIONAL SECTION:
- A.GTLD-SERVERS.NET. 86400 A 192.5.6.30 ;; @320
- B.GTLD-SERVERS.NET. 86400 A 192.33.14.30 ;; @336
- C.GTLD-SERVERS.NET. 86400 A 192.26.92.30 ;; @352
- D.GTLD-SERVERS.NET. 86400 A 192.31.80.30 ;; @368
- E.GTLD-SERVERS.NET. 86400 A 192.12.94.30 ;; @384
- F.GTLD-SERVERS.NET. 86400 A 192.35.51.30 ;; @400
- G.GTLD-SERVERS.NET. 86400 A 192.42.93.30 ;; @416
- H.GTLD-SERVERS.NET. 86400 A 192.54.112.30 ;; @432
- I.GTLD-SERVERS.NET. 86400 A 192.43.172.30 ;; @448
- J.GTLD-SERVERS.NET. 86400 A 192.48.79.30 ;; @464
- K.GTLD-SERVERS.NET. 86400 A 192.52.178.30 ;; @480
- L.GTLD-SERVERS.NET. 86400 A 192.41.162.30 ;; @496
- M.GTLD-SERVERS.NET. 86400 A 192.55.83.30 ;; @512
-
- ;; MSG SIZE sent: 80 rcvd: 512
-
- 3.2. For longer query names, the number of address records supplied will
- be lower. Furthermore, it is only by using a common parent name (which
- is GTLD-SERVERS.NET in this example) that all 13 addresses are able to
- fit, due to the use of DNS compression pointers in the last 12
- occurances of the parent domain name. The following output from a
- response simulator demonstrates these properties.
-
- % perl respsize.pl a.dns.br b.dns.br c.dns.br d.dns.br
- a.dns.br requires 10 bytes
- b.dns.br requires 4 bytes
- c.dns.br requires 4 bytes
- d.dns.br requires 4 bytes
- # of NS: 4
- For maximum size query (255 byte):
- only A is considered: # of A is 4 (green)
- A and AAAA are considered: # of A+AAAA is 3 (yellow)
- preferred-glue A is assumed: # of A is 4, # of AAAA is 3 (yellow)
- For average size query (64 byte):
- only A is considered: # of A is 4 (green)
- A and AAAA are considered: # of A+AAAA is 4 (green)
- preferred-glue A is assumed: # of A is 4, # of AAAA is 4 (green)
-
-
-
-
-
-
-
-
-
-
- Expires January 2007 [Page 6]
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- INTERNET-DRAFT August 2006 RESPSIZE
-
-
- % perl respsize.pl ns-ext.isc.org ns.psg.com ns.ripe.net ns.eu.int
- ns-ext.isc.org requires 16 bytes
- ns.psg.com requires 12 bytes
- ns.ripe.net requires 13 bytes
- ns.eu.int requires 11 bytes
- # of NS: 4
- For maximum size query (255 byte):
- only A is considered: # of A is 4 (green)
- A and AAAA are considered: # of A+AAAA is 3 (yellow)
- preferred-glue A is assumed: # of A is 4, # of AAAA is 2 (yellow)
- For average size query (64 byte):
- only A is considered: # of A is 4 (green)
- A and AAAA are considered: # of A+AAAA is 4 (green)
- preferred-glue A is assumed: # of A is 4, # of AAAA is 4 (green)
-
- (Note: The response simulator program is shown in Section 5.)
-
- Here we use the term "green" if all address records could fit, or
- "yellow" if two or more could fit, or "orange" if only one could fit, or
- "red" if no address record could fit. It's clear that without a common
- parent for nameserver names, much space would be lost. For these
- examples we use an average/common name size of 15 octets, befitting our
- assumption of GTLD-SERVERS.NET as our common parent name.
-
- We're assuming a medium query name size of 64 since that is the typical
- size seen in trace data at the time of this writing. If
- Internationalized Domain Name (IDN) or any other technology which
- results in larger query names be deployed significantly in advance of
- EDNS, then new measurements and new estimates will have to be made.
-
- 4 - Conclusions
-
- 4.1. The current practice of giving all nameserver names a common parent
- (such as GTLD-SERVERS.NET or ROOT-SERVERS.NET) saves space in DNS
- responses and allows for more nameservers to be enumerated than would
- otherwise be possible, since the common parent domain name only appears
- once in a DNS message and is referred to via "compression pointers"
- thereafter.
-
- 4.2. If all nameserver names for a zone share a common parent, then it
- is operationally advisable to make all servers for the zone thus served
- also be authoritative for the zone of that common parent. For example,
- the root name servers (?.ROOT-SERVERS.NET) can answer authoritatively
- for the ROOT-SERVERS.NET. This is to ensure that the zone's servers
- always have the zone's nameservers' glue available when delegating, and
-
-
-
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-
-
- will be able to respond with answers rather than referrals if a
- requester who wants that glue comes back asking for it. In this case
- the name server will likely be a "stealth server" -- authoritative but
- unadvertised in the glue zone's NS RRset. See [RFC1996 2] for more
- information about stealth servers.
-
- 4.3. Thirteen (13) is the effective maximum number of nameserver names
- usable traditional (non-extended) DNS, assuming a common parent domain
- name, and given that implicit referral response truncation is
- undesirable in the average case.
-
- 4.4. Multi-homing of name servers within a protocol family is
- inadvisable since the necessary glue RRsets (A or AAAA) are atomically
- indivisible, and will be larger than a single resource record. Larger
- RRsets are more likely to lead to or encounter truncation.
-
- 4.5. Multi-homing of name servers across protocol families is less
- likely to lead to or encounter truncation, partly because multiprotocol
- clients are more likely to speak EDNS which can use a larger response
- size limit, and partly because the resource records (A and AAAA) are in
- different RRsets and are therefore divisible from each other.
-
- 4.6. Name server names which are at or below the zone they serve are
- more sensitive to referral response truncation, and glue records for
- them should be considered "less optional" than other glue records, in
- the assembly of referral responses.
-
- 4.7. If a zone is served by thirteen (13) name servers having a common
- parent name (such as ?.ROOT-SERVERS.NET) and each such name server has a
- single address record in some protocol family (e.g., an A RR), then all
- thirteen name servers or any subset thereof could multi-home in a second
- protocol family by adding a second address record (e.g., an AAAA RR)
- without reducing the reachability of the zone thus served.
-
- 5 - Source Code
-
- #!/usr/bin/perl
- #
- # SYNOPSIS
- # repsize.pl [ -z zone ] fqdn_ns1 fqdn_ns2 ...
- # if all queries are assumed to have a same zone suffix,
- # such as "jp" in JP TLD servers, specify it in -z option
- #
- use strict;
- use Getopt::Std;
-
-
-
- Expires January 2007 [Page 8]
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- INTERNET-DRAFT August 2006 RESPSIZE
-
-
- my ($sz_msg) = (512);
- my ($sz_header, $sz_ptr, $sz_rr_a, $sz_rr_aaaa) = (12, 2, 16, 28);
- my ($sz_type, $sz_class, $sz_ttl, $sz_rdlen) = (2, 2, 4, 2);
- my (%namedb, $name, $nssect, %opts, $optz);
- my $n_ns = 0;
-
- getopt('z', %opts);
- if (defined($opts{'z'})) {
- server_name_len($opts{'z'}); # just register it
- }
-
- foreach $name (@ARGV) {
- my $len;
- $n_ns++;
- $len = server_name_len($name);
- print "$name requires $len bytes\n";
- $nssect += $sz_ptr + $sz_type + $sz_class + $sz_ttl
- + $sz_rdlen + $len;
- }
- print "# of NS: $n_ns\n";
- arsect(255, $nssect, $n_ns, "maximum");
- arsect(64, $nssect, $n_ns, "average");
-
- sub server_name_len {
- my ($name) = @_;
- my (@labels, $len, $n, $suffix);
-
- $name =~ tr/A-Z/a-z/;
- @labels = split(/\./, $name);
- $len = length(join('.', @labels)) + 2;
- for ($n = 0; $#labels >= 0; $n++, shift @labels) {
- $suffix = join('.', @labels);
- return length($name) - length($suffix) + $sz_ptr
- if (defined($namedb{$suffix}));
- $namedb{$suffix} = 1;
- }
- return $len;
- }
-
- sub arsect {
- my ($sz_query, $nssect, $n_ns, $cond) = @_;
- my ($space, $n_a, $n_a_aaaa, $n_p_aaaa, $ansect);
- $ansect = $sz_query + 1 + $sz_type + $sz_class;
- $space = $sz_msg - $sz_header - $ansect - $nssect;
- $n_a = atmost(int($space / $sz_rr_a), $n_ns);
-
-
-
- Expires January 2007 [Page 9]
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- INTERNET-DRAFT August 2006 RESPSIZE
-
-
- $n_a_aaaa = atmost(int($space
- / ($sz_rr_a + $sz_rr_aaaa)), $n_ns);
- $n_p_aaaa = atmost(int(($space - $sz_rr_a * $n_ns)
- / $sz_rr_aaaa), $n_ns);
- printf "For %s size query (%d byte):\n", $cond, $sz_query;
- printf " only A is considered: ";
- printf "# of A is %d (%s)\n", $n_a, &judge($n_a, $n_ns);
- printf " A and AAAA are considered: ";
- printf "# of A+AAAA is %d (%s)\n",
- $n_a_aaaa, &judge($n_a_aaaa, $n_ns);
- printf " preferred-glue A is assumed: ";
- printf "# of A is %d, # of AAAA is %d (%s)\n",
- $n_a, $n_p_aaaa, &judge($n_p_aaaa, $n_ns);
- }
-
- sub judge {
- my ($n, $n_ns) = @_;
- return "green" if ($n >= $n_ns);
- return "yellow" if ($n >= 2);
- return "orange" if ($n == 1);
- return "red";
- }
-
- sub atmost {
- my ($a, $b) = @_;
- return 0 if ($a < 0);
- return $b if ($a > $b);
- return $a;
- }
-
- 6 - Security Considerations
-
- The recommendations contained in this document have no known security
- implications.
-
- 7 - IANA Considerations
-
- This document does not call for changes or additions to any IANA
- registry.
-
- 8 - Acknowledgement
-
- The authors thank Peter Koch, Rob Austein, Joe Abley, and Mark Andrews
- for their valuable comments and suggestions.
-
-
-
-
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-
-
- This work was supported by the US National Science Foundation (research
- grant SCI-0427144) and DNS-OARC.
-
- 9 - References
-
- [RFC1034] Mockapetris, P.V., "Domain names - Concepts and Facilities",
- RFC1034, November 1987.
-
- [RFC1035] Mockapetris, P.V., "Domain names - Implementation and
- Specification", RFC1035, November 1987.
-
- [RFC1123] Braden, R., Ed., "Requirements for Internet Hosts -
- Application and Support", RFC1123, October 1989.
-
- [RFC1996] Vixie, P., "A Mechanism for Prompt Notification of Zone
- Changes (DNS NOTIFY)", RFC1996, August 1996.
-
- [RFC2181] Elz, R., Bush, R., "Clarifications to the DNS Specification",
- RFC2181, July 1997.
-
- [RFC2308] Andrews, M., "Negative Caching of DNS Queries (DNS NCACHE)",
- RFC2308, March 1998.
-
- [RFC2671] Vixie, P., "Extension Mechanisms for DNS (EDNS0)", RFC2671,
- August 1999.
-
- [RFC4472] Durand, A., Ihren, J., Savola, P., "Operational Consideration
- and Issues with IPV6 DNS", April 2006.
-
- 10 - Authors' Addresses
-
- Paul Vixie
- Internet Systems Consortium, Inc.
- 950 Charter Street
- Redwood City, CA 94063
- +1 650 423 1301
- vixie@isc.org
-
- Akira Kato
- University of Tokyo, Information Technology Center
- 2-11-16 Yayoi Bunkyo
- Tokyo 113-8658, JAPAN
- +81 3 5841 2750
- kato@wide.ad.jp
-
-
-
-
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-
-
- Full Copyright Statement
-
- Copyright (C) The Internet Society (2006).
-
- This document is subject to the rights, licenses and restrictions
- contained in BCP 78, and except as set forth therein, the authors retain
- all their rights.
-
- This document and the information contained herein are provided on an
- "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS OR
- IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND THE INTERNET
- ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED,
- INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE
- INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED
- WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
-
- Intellectual Property
-
- The IETF takes no position regarding the validity or scope of any
- Intellectual Property Rights or other rights that might be claimed to
- pertain to the implementation or use of the technology described in this
- document or the extent to which any license under such rights might or
- might not be available; nor does it represent that it has made any
- independent effort to identify any such rights. Information on the
- procedures with respect to rights in RFC documents can be found in BCP
- 78 and BCP 79.
-
- Copies of IPR disclosures made to the IETF Secretariat and any
- assurances of licenses to be made available, or the result of an attempt
- made to obtain a general license or permission for the use of such
- proprietary rights by implementers or users of this specification can be
- obtained from the IETF on-line IPR repository at
- http://www.ietf.org/ipr.
-
- The IETF invites any interested party to bring to its attention any
- copyrights, patents or patent applications, or other proprietary rights
- that may cover technology that may be required to implement this
- standard. Please address the information to the IETF at
- ietf-ipr@ietf.org.
-
- Acknowledgement
-
- Funding for the RFC Editor function is provided by the IETF
- Administrative Support Activity (IASA).
-
-
-
-
- Expires January 2007 [Page 12]
-\f
-
+++ /dev/null
-
-
-
-
-
-
-Network Working Group S. Josefsson
-Request for Comments: 4398 March 2006
-Obsoletes: 2538
-Category: Standards Track
-
-
- Storing Certificates in the Domain Name System (DNS)
-
-Status of This Memo
-
- This document specifies an Internet standards track protocol for the
- Internet community, and requests discussion and suggestions for
- improvements. Please refer to the current edition of the "Internet
- Official Protocol Standards" (STD 1) for the standardization state
- and status of this protocol. Distribution of this memo is unlimited.
-
-Copyright Notice
-
- Copyright (C) The Internet Society (2006).
-
-Abstract
-
- Cryptographic public keys are frequently published, and their
- authenticity is demonstrated by certificates. A CERT resource record
- (RR) is defined so that such certificates and related certificate
- revocation lists can be stored in the Domain Name System (DNS).
-
- This document obsoletes RFC 2538.
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-Josefsson Standards Track [Page 1]
-\f
-RFC 4398 Storing Certificates in the DNS February 2006
-
-
-Table of Contents
-
- 1. Introduction ....................................................3
- 2. The CERT Resource Record ........................................3
- 2.1. Certificate Type Values ....................................4
- 2.2. Text Representation of CERT RRs ............................6
- 2.3. X.509 OIDs .................................................6
- 3. Appropriate Owner Names for CERT RRs ............................7
- 3.1. Content-Based X.509 CERT RR Names ..........................8
- 3.2. Purpose-Based X.509 CERT RR Names ..........................9
- 3.3. Content-Based OpenPGP CERT RR Names ........................9
- 3.4. Purpose-Based OpenPGP CERT RR Names .......................10
- 3.5. Owner Names for IPKIX, ISPKI, IPGP, and IACPKIX ...........10
- 4. Performance Considerations .....................................11
- 5. Contributors ...................................................11
- 6. Acknowledgements ...............................................11
- 7. Security Considerations ........................................12
- 8. IANA Considerations ............................................12
- 9. Changes since RFC 2538 .........................................13
- 10. References ....................................................14
- 10.1. Normative References .....................................14
- 10.2. Informative References ...................................15
- Appendix A. Copying Conditions ...................................16
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-Josefsson Standards Track [Page 2]
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-RFC 4398 Storing Certificates in the DNS February 2006
-
-
-1. Introduction
-
- Public keys are frequently published in the form of a certificate,
- and their authenticity is commonly demonstrated by certificates and
- related certificate revocation lists (CRLs). A certificate is a
- binding, through a cryptographic digital signature, of a public key,
- a validity interval and/or conditions, and identity, authorization,
- or other information. A certificate revocation list is a list of
- certificates that are revoked, and of incidental information, all
- signed by the signer (issuer) of the revoked certificates. Examples
- are X.509 certificates/CRLs in the X.500 directory system or OpenPGP
- certificates/revocations used by OpenPGP software.
-
- Section 2 specifies a CERT resource record (RR) for the storage of
- certificates in the Domain Name System [1] [2].
-
- Section 3 discusses appropriate owner names for CERT RRs.
-
- Sections 4, 7, and 8 cover performance, security, and IANA
- considerations, respectively.
-
- Section 9 explains the changes in this document compared to RFC 2538.
-
- The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
- "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
- document are to be interpreted as described in [3].
-
-2. The CERT Resource Record
-
- The CERT resource record (RR) has the structure given below. Its RR
- type code is 37.
-
- 1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 2 3 3
- 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
- +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
- | type | key tag |
- +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
- | algorithm | /
- +---------------+ certificate or CRL /
- / /
- +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-|
-
- The type field is the certificate type as defined in Section 2.1
- below.
-
- The key tag field is the 16-bit value computed for the key embedded
- in the certificate, using the RRSIG Key Tag algorithm described in
- Appendix B of [12]. This field is used as an efficiency measure to
-
-
-
-Josefsson Standards Track [Page 3]
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-RFC 4398 Storing Certificates in the DNS February 2006
-
-
- pick which CERT RRs may be applicable to a particular key. The key
- tag can be calculated for the key in question, and then only CERT RRs
- with the same key tag need to be examined. Note that two different
- keys can have the same key tag. However, the key MUST be transformed
- to the format it would have as the public key portion of a DNSKEY RR
- before the key tag is computed. This is only possible if the key is
- applicable to an algorithm and complies to limits (such as key size)
- defined for DNS security. If it is not, the algorithm field MUST be
- zero and the tag field is meaningless and SHOULD be zero.
-
- The algorithm field has the same meaning as the algorithm field in
- DNSKEY and RRSIG RRs [12], except that a zero algorithm field
- indicates that the algorithm is unknown to a secure DNS, which may
- simply be the result of the algorithm not having been standardized
- for DNSSEC [11].
-
-2.1. Certificate Type Values
-
- The following values are defined or reserved:
-
- Value Mnemonic Certificate Type
- ----- -------- ----------------
- 0 Reserved
- 1 PKIX X.509 as per PKIX
- 2 SPKI SPKI certificate
- 3 PGP OpenPGP packet
- 4 IPKIX The URL of an X.509 data object
- 5 ISPKI The URL of an SPKI certificate
- 6 IPGP The fingerprint and URL of an OpenPGP packet
- 7 ACPKIX Attribute Certificate
- 8 IACPKIX The URL of an Attribute Certificate
- 9-252 Available for IANA assignment
- 253 URI URI private
- 254 OID OID private
- 255 Reserved
- 256-65279 Available for IANA assignment
- 65280-65534 Experimental
- 65535 Reserved
-
- These values represent the initial content of the IANA registry; see
- Section 8.
-
- The PKIX type is reserved to indicate an X.509 certificate conforming
- to the profile defined by the IETF PKIX working group [8]. The
- certificate section will start with a one-octet unsigned OID length
- and then an X.500 OID indicating the nature of the remainder of the
-
-
-
-
-
-Josefsson Standards Track [Page 4]
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-RFC 4398 Storing Certificates in the DNS February 2006
-
-
- certificate section (see Section 2.3, below). (NOTE: X.509
- certificates do not include their X.500 directory-type-designating
- OID as a prefix.)
-
- The SPKI and ISPKI types are reserved to indicate the SPKI
- certificate format [15], for use when the SPKI documents are moved
- from experimental status. The format for these two CERT RR types
- will need to be specified later.
-
- The PGP type indicates an OpenPGP packet as described in [5] and its
- extensions and successors. This is used to transfer public key
- material and revocation signatures. The data is binary and MUST NOT
- be encoded into an ASCII armor. An implementation SHOULD process
- transferable public keys as described in Section 10.1 of [5], but it
- MAY handle additional OpenPGP packets.
-
- The ACPKIX type indicates an Attribute Certificate format [9].
-
- The IPKIX and IACPKIX types indicate a URL that will serve the
- content that would have been in the "certificate, CRL, or URL" field
- of the corresponding type (PKIX or ACPKIX, respectively).
-
- The IPGP type contains both an OpenPGP fingerprint for the key in
- question, as well as a URL. The certificate portion of the IPGP CERT
- RR is defined as a one-octet fingerprint length, followed by the
- OpenPGP fingerprint, followed by the URL. The OpenPGP fingerprint is
- calculated as defined in RFC 2440 [5]. A zero-length fingerprint or
- a zero-length URL are legal, and indicate URL-only IPGP data or
- fingerprint-only IPGP data, respectively. A zero-length fingerprint
- and a zero-length URL are meaningless and invalid.
-
- The IPKIX, ISPKI, IPGP, and IACPKIX types are known as "indirect".
- These types MUST be used when the content is too large to fit in the
- CERT RR and MAY be used at the implementer's discretion. They SHOULD
- NOT be used where the DNS message is 512 octets or smaller and could
- thus be expected to fit a UDP packet.
-
- The URI private type indicates a certificate format defined by an
- absolute URI. The certificate portion of the CERT RR MUST begin with
- a null-terminated URI [10], and the data after the null is the
- private format certificate itself. The URI SHOULD be such that a
- retrieval from it will lead to documentation on the format of the
- certificate. Recognition of private certificate types need not be
- based on URI equality but can use various forms of pattern matching
- so that, for example, subtype or version information can also be
- encoded into the URI.
-
-
-
-
-
-Josefsson Standards Track [Page 5]
-\f
-RFC 4398 Storing Certificates in the DNS February 2006
-
-
- The OID private type indicates a private format certificate specified
- by an ISO OID prefix. The certificate section will start with a
- one-octet unsigned OID length and then a BER-encoded OID indicating
- the nature of the remainder of the certificate section. This can be
- an X.509 certificate format or some other format. X.509 certificates
- that conform to the IETF PKIX profile SHOULD be indicated by the PKIX
- type, not the OID private type. Recognition of private certificate
- types need not be based on OID equality but can use various forms of
- pattern matching such as OID prefix.
-
-2.2. Text Representation of CERT RRs
-
- The RDATA portion of a CERT RR has the type field as an unsigned
- decimal integer or as a mnemonic symbol as listed in Section 2.1,
- above.
-
- The key tag field is represented as an unsigned decimal integer.
-
- The algorithm field is represented as an unsigned decimal integer or
- a mnemonic symbol as listed in [12].
-
- The certificate/CRL portion is represented in base 64 [16] and may be
- divided into any number of white-space-separated substrings, down to
- single base-64 digits, which are concatenated to obtain the full
- signature. These substrings can span lines using the standard
- parenthesis.
-
- Note that the certificate/CRL portion may have internal sub-fields,
- but these do not appear in the master file representation. For
- example, with type 254, there will be an OID size, an OID, and then
- the certificate/CRL proper. However, only a single logical base-64
- string will appear in the text representation.
-
-2.3. X.509 OIDs
-
- OIDs have been defined in connection with the X.500 directory for
- user certificates, certification authority certificates, revocations
- of certification authority, and revocations of user certificates.
- The following table lists the OIDs, their BER encoding, and their
- length-prefixed hex format for use in CERT RRs:
-
-
-
-
-
-
-
-
-
-
-
-Josefsson Standards Track [Page 6]
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-RFC 4398 Storing Certificates in the DNS February 2006
-
-
- id-at-userCertificate
- = { joint-iso-ccitt(2) ds(5) at(4) 36 }
- == 0x 03 55 04 24
- id-at-cACertificate
- = { joint-iso-ccitt(2) ds(5) at(4) 37 }
- == 0x 03 55 04 25
- id-at-authorityRevocationList
- = { joint-iso-ccitt(2) ds(5) at(4) 38 }
- == 0x 03 55 04 26
- id-at-certificateRevocationList
- = { joint-iso-ccitt(2) ds(5) at(4) 39 }
- == 0x 03 55 04 27
-
-3. Appropriate Owner Names for CERT RRs
-
- It is recommended that certificate CERT RRs be stored under a domain
- name related to their subject, i.e., the name of the entity intended
- to control the private key corresponding to the public key being
- certified. It is recommended that certificate revocation list CERT
- RRs be stored under a domain name related to their issuer.
-
- Following some of the guidelines below may result in DNS names with
- characters that require DNS quoting as per Section 5.1 of RFC 1035
- [2].
-
- The choice of name under which CERT RRs are stored is important to
- clients that perform CERT queries. In some situations, the clients
- may not know all information about the CERT RR object it wishes to
- retrieve. For example, a client may not know the subject name of an
- X.509 certificate, or the email address of the owner of an OpenPGP
- key. Further, the client might only know the hostname of a service
- that uses X.509 certificates or the Key ID of an OpenPGP key.
-
- Therefore, two owner name guidelines are defined: content-based owner
- names and purpose-based owner names. A content-based owner name is
- derived from the content of the CERT RR data; for example, the
- Subject field in an X.509 certificate or the User ID field in OpenPGP
- keys. A purpose-based owner name is a name that a client retrieving
- CERT RRs ought to know already; for example, the host name of an
- X.509 protected service or the Key ID of an OpenPGP key. The
- content-based and purpose-based owner name may be the same; for
- example, when a client looks up a key based on the From: address of
- an incoming email.
-
- Implementations SHOULD use the purpose-based owner name guidelines
- described in this document and MAY use CNAME RRs at content-based
- owner names (or other names), pointing to the purpose-based owner
- name.
-
-
-
-Josefsson Standards Track [Page 7]
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-
-
- Note that this section describes an application-based mapping from
- the name space used in a certificate to the name space used by DNS.
- The DNS does not infer any relationship amongst CERT resource records
- based on similarities or differences of the DNS owner name(s) of CERT
- resource records. For example, if multiple labels are used when
- mapping from a CERT identifier to a domain name, then care must be
- taken in understanding wildcard record synthesis.
-
-3.1. Content-Based X.509 CERT RR Names
-
- Some X.509 versions, such as the PKIX profile of X.509 [8], permit
- multiple names to be associated with subjects and issuers under
- "Subject Alternative Name" and "Issuer Alternative Name". For
- example, the PKIX profile has such Alternate Names with an ASN.1
- specification as follows:
-
- GeneralName ::= CHOICE {
- otherName [0] OtherName,
- rfc822Name [1] IA5String,
- dNSName [2] IA5String,
- x400Address [3] ORAddress,
- directoryName [4] Name,
- ediPartyName [5] EDIPartyName,
- uniformResourceIdentifier [6] IA5String,
- iPAddress [7] OCTET STRING,
- registeredID [8] OBJECT IDENTIFIER }
-
- The recommended locations of CERT storage are as follows, in priority
- order:
-
- 1. If a domain name is included in the identification in the
- certificate or CRL, that ought to be used.
- 2. If a domain name is not included but an IP address is included,
- then the translation of that IP address into the appropriate
- inverse domain name ought to be used.
- 3. If neither of the above is used, but a URI containing a domain
- name is present, that domain name ought to be used.
- 4. If none of the above is included but a character string name is
- included, then it ought to be treated as described below for
- OpenPGP names.
- 5. If none of the above apply, then the distinguished name (DN)
- ought to be mapped into a domain name as specified in [4].
-
- Example 1: An X.509v3 certificate is issued to /CN=John Doe /DC=Doe/
- DC=com/DC=xy/O=Doe Inc/C=XY/ with Subject Alternative Names of (a)
- string "John (the Man) Doe", (b) domain name john-doe.com, and (c)
- URI <https://www.secure.john-doe.com:8080/>. The storage locations
- recommended, in priority order, would be
-
-
-
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-
-
- 1. john-doe.com,
- 2. www.secure.john-doe.com, and
- 3. Doe.com.xy.
-
- Example 2: An X.509v3 certificate is issued to /CN=James Hacker/
- L=Basingstoke/O=Widget Inc/C=GB/ with Subject Alternate names of (a)
- domain name widget.foo.example, (b) IPv4 address 10.251.13.201, and
- (c) string "James Hacker <hacker@mail.widget.foo.example>". The
- storage locations recommended, in priority order, would be
-
- 1. widget.foo.example,
- 2. 201.13.251.10.in-addr.arpa, and
- 3. hacker.mail.widget.foo.example.
-
-3.2. Purpose-Based X.509 CERT RR Names
-
- Due to the difficulty for clients that do not already possess a
- certificate to reconstruct the content-based owner name,
- purpose-based owner names are recommended in this section.
- Recommendations for purpose-based owner names vary per scenario. The
- following table summarizes the purpose-based X.509 CERT RR owner name
- guidelines for use with S/MIME [17], SSL/TLS [13], and IPsec [14]:
-
- Scenario Owner name
- ------------------ ----------------------------------------------
- S/MIME Certificate Standard translation of an RFC 2822 email
- address. Example: An S/MIME certificate for
- "postmaster@example.org" will use a standard
- hostname translation of the owner name,
- "postmaster.example.org".
-
- TLS Certificate Hostname of the TLS server.
-
- IPsec Certificate Hostname of the IPsec machine and/or, for IPv4
- or IPv6 addresses, the fully qualified domain
- name in the appropriate reverse domain.
-
- An alternate approach for IPsec is to store raw public keys [18].
-
-3.3. Content-Based OpenPGP CERT RR Names
-
- OpenPGP signed keys (certificates) use a general character string
- User ID [5]. However, it is recommended by OpenPGP that such names
- include the RFC 2822 [7] email address of the party, as in "Leslie
- Example <Leslie@host.example>". If such a format is used, the CERT
- ought to be under the standard translation of the email address into
-
-
-
-
-
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-
-
- a domain name, which would be leslie.host.example in this case. If
- no RFC 2822 name can be extracted from the string name, no specific
- domain name is recommended.
-
- If a user has more than one email address, the CNAME type can be used
- to reduce the amount of data stored in the DNS. For example:
-
- $ORIGIN example.org.
- smith IN CERT PGP 0 0 <OpenPGP binary>
- john.smith IN CNAME smith
- js IN CNAME smith
-
-3.4. Purpose-Based OpenPGP CERT RR Names
-
- Applications that receive an OpenPGP packet containing encrypted or
- signed data but do not know the email address of the sender will have
- difficulties constructing the correct owner name and cannot use the
- content-based owner name guidelines. However, these clients commonly
- know the key fingerprint or the Key ID. The key ID is found in
- OpenPGP packets, and the key fingerprint is commonly found in
- auxiliary data that may be available. In this case, use of an owner
- name identical to the key fingerprint and the key ID expressed in
- hexadecimal [16] is recommended. For example:
-
- $ORIGIN example.org.
- 0424D4EE81A0E3D119C6F835EDA21E94B565716F IN CERT PGP ...
- F835EDA21E94B565716F IN CERT PGP ...
- B565716F IN CERT PGP ...
-
- If the same key material is stored for several owner names, the use
- of CNAME may help avoid data duplication. Note that CNAME is not
- always applicable, because it maps one owner name to the other for
- all purposes, which may be sub-optimal when two keys with the same
- Key ID are stored.
-
-3.5. Owner Names for IPKIX, ISPKI, IPGP, and IACPKIX
-
- These types are stored under the same owner names, both purpose- and
- content-based, as the PKIX, SPKI, PGP, and ACPKIX types.
-
-
-
-
-
-
-
-
-
-
-
-
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-
-
-4. Performance Considerations
-
- The Domain Name System (DNS) protocol was designed for small
- transfers, typically below 512 octets. While larger transfers will
- perform correctly and work is underway to make larger transfers more
- efficient, it is still advisable at this time that every reasonable
- effort be made to minimize the size of certificates stored within the
- DNS. Steps that can be taken may include using the fewest possible
- optional or extension fields and using short field values for
- necessary variable-length fields.
-
- The RDATA field in the DNS protocol may only hold data of size 65535
- octets (64kb) or less. This means that each CERT RR MUST NOT contain
- more than 64kb of payload, even if the corresponding certificate or
- certificate revocation list is larger. This document addresses this
- by defining "indirect" data types for each normal type.
-
- Deploying CERT RRs to support digitally signed email changes the
- access patterns of DNS lookups from per-domain to per-user. If
- digitally signed email and a key/certificate lookup based on CERT RRs
- are deployed on a wide scale, this may lead to an increased DNS load,
- with potential performance and cache effectiveness consequences.
- Whether or not this load increase will be noticeable is not known.
-
-5. Contributors
-
- The majority of this document is copied verbatim from RFC 2538, by
- Donald Eastlake 3rd and Olafur Gudmundsson.
-
-6. Acknowledgements
-
- Thanks to David Shaw and Michael Graff for their contributions to
- earlier works that motivated, and served as inspiration for, this
- document.
-
- This document was improved by suggestions and comments from Olivier
- Dubuisson, Scott Hollenbeck, Russ Housley, Peter Koch, Olaf M.
- Kolkman, Ben Laurie, Edward Lewis, John Loughney, Allison Mankin,
- Douglas Otis, Marcos Sanz, Pekka Savola, Jason Sloderbeck, Samuel
- Weiler, and Florian Weimer. No doubt the list is incomplete. We
- apologize to anyone we left out.
-
-
-
-
-
-
-
-
-
-
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-
-
-7. Security Considerations
-
- By definition, certificates contain their own authenticating
- signatures. Thus, it is reasonable to store certificates in
- non-secure DNS zones or to retrieve certificates from DNS with DNS
- security checking not implemented or deferred for efficiency. The
- results may be trusted if the certificate chain is verified back to a
- known trusted key and this conforms with the user's security policy.
-
- Alternatively, if certificates are retrieved from a secure DNS zone
- with DNS security checking enabled and are verified by DNS security,
- the key within the retrieved certificate may be trusted without
- verifying the certificate chain if this conforms with the user's
- security policy.
-
- If an organization chooses to issue certificates for its employees,
- placing CERT RRs in the DNS by owner name, and if DNSSEC (with NSEC)
- is in use, it is possible for someone to enumerate all employees of
- the organization. This is usually not considered desirable, for the
- same reason that enterprise phone listings are not often publicly
- published and are even marked confidential.
-
- Using the URI type introduces another level of indirection that may
- open a new vulnerability. One method of securing that indirection is
- to include a hash of the certificate in the URI itself.
-
- If DNSSEC is used, then the non-existence of a CERT RR and,
- consequently, certificates or revocation lists can be securely
- asserted. Without DNSSEC, this is not possible.
-
-8. IANA Considerations
-
- The IANA has created a new registry for CERT RR: certificate types.
- The initial contents of this registry is:
-
- Decimal Type Meaning Reference
- ------- ---- ------- ---------
- 0 Reserved RFC 4398
- 1 PKIX X.509 as per PKIX RFC 4398
- 2 SPKI SPKI certificate RFC 4398
- 3 PGP OpenPGP packet RFC 4398
- 4 IPKIX The URL of an X.509 data object RFC 4398
- 5 ISPKI The URL of an SPKI certificate RFC 4398
- 6 IPGP The fingerprint and URL RFC 4398
- of an OpenPGP packet
- 7 ACPKIX Attribute Certificate RFC 4398
- 8 IACPKIX The URL of an Attribute RFC 4398
- Certificate
-
-
-
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-
-
- 9-252 Available for IANA assignment
- by IETF Standards action
- 253 URI URI private RFC 4398
- 254 OID OID private RFC 4398
- 255 Reserved RFC 4398
- 256-65279 Available for IANA assignment
- by IETF Consensus
- 65280-65534 Experimental RFC 4398
- 65535 Reserved RFC 4398
-
- Certificate types 0x0000 through 0x00FF and 0xFF00 through 0xFFFF can
- only be assigned by an IETF standards action [6]. This document
- assigns 0x0001 through 0x0008 and 0x00FD and 0x00FE. Certificate
- types 0x0100 through 0xFEFF are assigned through IETF Consensus [6]
- based on RFC documentation of the certificate type. The availability
- of private types under 0x00FD and 0x00FE ought to satisfy most
- requirements for proprietary or private types.
-
- The CERT RR reuses the DNS Security Algorithm Numbers registry. In
- particular, the CERT RR requires that algorithm number 0 remain
- reserved, as described in Section 2. The IANA will reference the
- CERT RR as a user of this registry and value 0, in particular.
-
-9. Changes since RFC 2538
-
- 1. Editorial changes to conform with new document requirements,
- including splitting reference section into two parts and
- updating the references to point at latest versions, and to add
- some additional references.
- 2. Improve terminology. For example replace "PGP" with "OpenPGP",
- to align with RFC 2440.
- 3. In Section 2.1, clarify that OpenPGP public key data are binary,
- not the ASCII armored format, and reference 10.1 in RFC 2440 on
- how to deal with OpenPGP keys, and acknowledge that
- implementations may handle additional packet types.
- 4. Clarify that integers in the representation format are decimal.
- 5. Replace KEY/SIG with DNSKEY/RRSIG etc, to align with DNSSECbis
- terminology. Improve reference for Key Tag Algorithm
- calculations.
- 6. Add examples that suggest use of CNAME to reduce bandwidth.
- 7. In Section 3, appended the last paragraphs that discuss
- "content-based" vs "purpose-based" owner names. Add Section 3.2
- for purpose-based X.509 CERT owner names, and Section 3.4 for
- purpose-based OpenPGP CERT owner names.
- 8. Added size considerations.
- 9. The SPKI types has been reserved, until RFC 2692/2693 is moved
- from the experimental status.
- 10. Added indirect types IPKIX, ISPKI, IPGP, and IACPKIX.
-
-
-
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-
-
- 11. An IANA registry of CERT type values was created.
-
-10. References
-
-10.1. Normative References
-
- [1] Mockapetris, P., "Domain names - concepts and facilities",
- STD 13, RFC 1034, November 1987.
-
- [2] Mockapetris, P., "Domain names - implementation and
- specification", STD 13, RFC 1035, November 1987.
-
- [3] Bradner, S., "Key words for use in RFCs to Indicate Requirement
- Levels", BCP 14, RFC 2119, March 1997.
-
- [4] Kille, S., Wahl, M., Grimstad, A., Huber, R., and S. Sataluri,
- "Using Domains in LDAP/X.500 Distinguished Names", RFC 2247,
- January 1998.
-
- [5] Callas, J., Donnerhacke, L., Finney, H., and R. Thayer,
- "OpenPGP Message Format", RFC 2440, November 1998.
-
- [6] Narten, T. and H. Alvestrand, "Guidelines for Writing an IANA
- Considerations Section in RFCs", BCP 26, RFC 2434,
- October 1998.
-
- [7] Resnick, P., "Internet Message Format", RFC 2822, April 2001.
-
- [8] Housley, R., Polk, W., Ford, W., and D. Solo, "Internet X.509
- Public Key Infrastructure Certificate and Certificate
- Revocation List (CRL) Profile", RFC 3280, April 2002.
-
- [9] Farrell, S. and R. Housley, "An Internet Attribute Certificate
- Profile for Authorization", RFC 3281, April 2002.
-
- [10] Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform
- Resource Identifier (URI): Generic Syntax", STD 66, RFC 3986,
- January 2005.
-
- [11] Arends, R., Austein, R., Larson, M., Massey, D., and S. Rose,
- "DNS Security Introduction and Requirements", RFC 4033,
- March 2005.
-
- [12] Arends, R., Austein, R., Larson, M., Massey, D., and S. Rose,
- "Resource Records for the DNS Security Extensions", RFC 4034,
- March 2005.
-
-
-
-
-
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-
-
-10.2. Informative References
-
- [13] Dierks, T. and C. Allen, "The TLS Protocol Version 1.0",
- RFC 2246, January 1999.
-
- [14] Kent, S. and K. Seo, "Security Architecture for the Internet
- Protocol", RFC 4301, December 2005.
-
- [15] Ellison, C., Frantz, B., Lampson, B., Rivest, R., Thomas, B.,
- and T. Ylonen, "SPKI Certificate Theory", RFC 2693,
- September 1999.
-
- [16] Josefsson, S., "The Base16, Base32, and Base64 Data Encodings",
- RFC 3548, July 2003.
-
- [17] Ramsdell, B., "Secure/Multipurpose Internet Mail Extensions
- (S/MIME) Version 3.1 Message Specification", RFC 3851,
- July 2004.
-
- [18] Richardson, M., "A Method for Storing IPsec Keying Material in
- DNS", RFC 4025, March 2005.
-
-
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-
-
-Appendix A. Copying Conditions
-
- Regarding the portion of this document that was written by Simon
- Josefsson ("the author", for the remainder of this section), the
- author makes no guarantees and is not responsible for any damage
- resulting from its use. The author grants irrevocable permission to
- anyone to use, modify, and distribute it in any way that does not
- diminish the rights of anyone else to use, modify, and distribute it,
- provided that redistributed derivative works do not contain
- misleading author or version information. Derivative works need not
- be licensed under similar terms.
-
-Author's Address
-
- Simon Josefsson
-
- EMail: simon@josefsson.org
-
-
-
-
-
-
-
-
-
-
-
-
-
-
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-
-
-Full Copyright Statement
-
- Copyright (C) The Internet Society (2006).
-
- This document is subject to the rights, licenses and restrictions
- contained in BCP 78, and except as set forth therein, the authors
- retain all their rights.
-
- This document and the information contained herein are provided on an
- "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS
- OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND THE INTERNET
- ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED,
- INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE
- INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED
- WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
-
-Intellectual Property
-
- The IETF takes no position regarding the validity or scope of any
- Intellectual Property Rights or other rights that might be claimed to
- pertain to the implementation or use of the technology described in
- this document or the extent to which any license under such rights
- might or might not be available; nor does it represent that it has
- made any independent effort to identify any such rights. Information
- on the procedures with respect to rights in RFC documents can be
- found in BCP 78 and BCP 79.
-
- Copies of IPR disclosures made to the IETF Secretariat and any
- assurances of licenses to be made available, or the result of an
- attempt made to obtain a general license or permission for the use of
- such proprietary rights by implementers or users of this
- specification can be obtained from the IETF on-line IPR repository at
- http://www.ietf.org/ipr.
-
- The IETF invites any interested party to bring to its attention any
- copyrights, patents or patent applications, or other proprietary
- rights that may cover technology that may be required to implement
- this standard. Please address the information to the IETF at
- ietf-ipr@ietf.org.
-
-Acknowledgement
-
- Funding for the RFC Editor function is provided by the IETF
- Administrative Support Activity (IASA).
-
-
-
-
-
-
-
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+++ /dev/null
-
-
-
-
-
-
-Network Working Group M. Wong
-Request for Comments: 4408 W. Schlitt
-Category: Experimental April 2006
-
-
- Sender Policy Framework (SPF) for
- Authorizing Use of Domains in E-Mail, Version 1
-
-Status of This Memo
-
- This memo defines an Experimental Protocol for the Internet
- community. It does not specify an Internet standard of any kind.
- Discussion and suggestions for improvement are requested.
- Distribution of this memo is unlimited.
-
-Copyright Notice
-
- Copyright (C) The Internet Society (2006).
-
-IESG Note
-
- The following documents (RFC 4405, RFC 4406, RFC 4407, and RFC 4408)
- are published simultaneously as Experimental RFCs, although there is
- no general technical consensus and efforts to reconcile the two
- approaches have failed. As such, these documents have not received
- full IETF review and are published "AS-IS" to document the different
- approaches as they were considered in the MARID working group.
-
- The IESG takes no position about which approach is to be preferred
- and cautions the reader that there are serious open issues for each
- approach and concerns about using them in tandem. The IESG believes
- that documenting the different approaches does less harm than not
- documenting them.
-
- Note that the Sender ID experiment may use DNS records that may have
- been created for the current SPF experiment or earlier versions in
- this set of experiments. Depending on the content of the record,
- this may mean that Sender-ID heuristics would be applied incorrectly
- to a message. Depending on the actions associated by the recipient
- with those heuristics, the message may not be delivered or may be
- discarded on receipt.
-
- Participants relying on Sender ID experiment DNS records are warned
- that they may lose valid messages in this set of circumstances.
- aParticipants publishing SPF experiment DNS records should consider
- the advice given in section 3.4 of RFC 4406 and may wish to publish
- both v=spf1 and spf2.0 records to avoid the conflict.
-
-
-
-
-Wong & Schlitt Experimental [Page 1]
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-RFC 4408 Sender Policy Framework (SPF) April 2006
-
-
- Participants in the Sender-ID experiment need to be aware that the
- way Resent-* header fields are used will result in failure to receive
- legitimate email when interacting with standards-compliant systems
- (specifically automatic forwarders which comply with the standards by
- not adding Resent-* headers, and systems which comply with RFC 822
- but have not yet implemented RFC 2822 Resent-* semantics). It would
- be inappropriate to advance Sender-ID on the standards track without
- resolving this interoperability problem.
-
- The community is invited to observe the success or failure of the two
- approaches during the two years following publication, in order that
- a community consensus can be reached in the future.
-
-Abstract
-
- E-mail on the Internet can be forged in a number of ways. In
- particular, existing protocols place no restriction on what a sending
- host can use as the reverse-path of a message or the domain given on
- the SMTP HELO/EHLO commands. This document describes version 1 of
- the Sender Policy Framework (SPF) protocol, whereby a domain may
- explicitly authorize the hosts that are allowed to use its domain
- name, and a receiving host may check such authorization.
-
-Table of Contents
-
- 1. Introduction ....................................................4
- 1.1. Protocol Status ............................................4
- 1.2. Terminology ................................................5
- 2. Operation .......................................................5
- 2.1. The HELO Identity ..........................................5
- 2.2. The MAIL FROM Identity .....................................5
- 2.3. Publishing Authorization ...................................6
- 2.4. Checking Authorization .....................................6
- 2.5. Interpreting the Result ....................................7
- 2.5.1. None ................................................8
- 2.5.2. Neutral .............................................8
- 2.5.3. Pass ................................................8
- 2.5.4. Fail ................................................8
- 2.5.5. SoftFail ............................................9
- 2.5.6. TempError ...........................................9
- 2.5.7. PermError ...........................................9
- 3. SPF Records .....................................................9
- 3.1. Publishing ................................................10
- 3.1.1. DNS Resource Record Types ..........................10
- 3.1.2. Multiple DNS Records ...............................11
- 3.1.3. Multiple Strings in a Single DNS record ............11
- 3.1.4. Record Size ........................................11
- 3.1.5. Wildcard Records ...................................11
-
-
-
-Wong & Schlitt Experimental [Page 2]
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-RFC 4408 Sender Policy Framework (SPF) April 2006
-
-
- 4. The check_host() Function ......................................12
- 4.1. Arguments .................................................12
- 4.2. Results ...................................................13
- 4.3. Initial Processing ........................................13
- 4.4. Record Lookup .............................................13
- 4.5. Selecting Records .........................................13
- 4.6. Record Evaluation .........................................14
- 4.6.1. Term Evaluation ....................................14
- 4.6.2. Mechanisms .........................................15
- 4.6.3. Modifiers ..........................................15
- 4.7. Default Result ............................................16
- 4.8. Domain Specification ......................................16
- 5. Mechanism Definitions ..........................................16
- 5.1. "all" .....................................................17
- 5.2. "include" .................................................18
- 5.3. "a" .......................................................19
- 5.4. "mx" ......................................................20
- 5.5. "ptr" .....................................................20
- 5.6. "ip4" and "ip6" ...........................................21
- 5.7. "exists" ..................................................22
- 6. Modifier Definitions ...........................................22
- 6.1. redirect: Redirected Query ................................23
- 6.2. exp: Explanation ..........................................23
- 7. The Received-SPF Header Field ..................................25
- 8. Macros .........................................................27
- 8.1. Macro Definitions .........................................27
- 8.2. Expansion Examples ........................................30
- 9. Implications ...................................................31
- 9.1. Sending Domains ...........................................31
- 9.2. Mailing Lists .............................................32
- 9.3. Forwarding Services and Aliases ...........................32
- 9.4. Mail Services .............................................34
- 9.5. MTA Relays ................................................34
- 10. Security Considerations .......................................35
- 10.1. Processing Limits ........................................35
- 10.2. SPF-Authorized E-Mail May Contain Other False
- Identities ...............................................37
- 10.3. Spoofed DNS and IP Data ..................................37
- 10.4. Cross-User Forgery .......................................37
- 10.5. Untrusted Information Sources ............................38
- 10.6. Privacy Exposure .........................................38
- 11. Contributors and Acknowledgements .............................38
- 12. IANA Considerations ...........................................39
- 12.1. The SPF DNS Record Type ..................................39
- 12.2. The Received-SPF Mail Header Field .......................39
- 13. References ....................................................39
- 13.1. Normative References .....................................39
- 13.2. Informative References ...................................40
-
-
-
-Wong & Schlitt Experimental [Page 3]
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-RFC 4408 Sender Policy Framework (SPF) April 2006
-
-
- Appendix A. Collected ABNF .......................................42
- Appendix B. Extended Examples ....................................44
- B.1. Simple Examples ..........................................44
- B.2. Multiple Domain Example ..................................45
- B.3. DNSBL Style Example ......................................46
- B.4. Multiple Requirements Example ............................46
-
-1. Introduction
-
- The current E-Mail infrastructure has the property that any host
- injecting mail into the mail system can identify itself as any domain
- name it wants. Hosts can do this at a variety of levels: in
- particular, the session, the envelope, and the mail headers.
- Although this feature is desirable in some circumstances, it is a
- major obstacle to reducing Unsolicited Bulk E-Mail (UBE, aka spam).
- Furthermore, many domain name holders are understandably concerned
- about the ease with which other entities may make use of their domain
- names, often with malicious intent.
-
- This document defines a protocol by which domain owners may authorize
- hosts to use their domain name in the "MAIL FROM" or "HELO" identity.
- Compliant domain holders publish Sender Policy Framework (SPF)
- records specifying which hosts are permitted to use their names, and
- compliant mail receivers use the published SPF records to test the
- authorization of sending Mail Transfer Agents (MTAs) using a given
- "HELO" or "MAIL FROM" identity during a mail transaction.
-
- An additional benefit to mail receivers is that after the use of an
- identity is verified, local policy decisions about the mail can be
- made based on the sender's domain, rather than the host's IP address.
- This is advantageous because reputation of domain names is likely to
- be more accurate than reputation of host IP addresses. Furthermore,
- if a claimed identity fails verification, local policy can take
- stronger action against such E-Mail, such as rejecting it.
-
-1.1. Protocol Status
-
- SPF has been in development since the summer of 2003 and has seen
- deployment beyond the developers beginning in December 2003. The
- design of SPF slowly evolved until the spring of 2004 and has since
- stabilized. There have been quite a number of forms of SPF, some
- written up as documents, some submitted as Internet Drafts, and many
- discussed and debated in development forums.
-
- The goal of this document is to clearly document the protocol defined
- by earlier draft specifications of SPF as used in existing
- implementations. This conception of SPF is sometimes called "SPF
- Classic". It is understood that particular implementations and
-
-
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-
- deployments may differ from, and build upon, this work. It is hoped
- that we have nonetheless captured the common understanding of SPF
- version 1.
-
-1.2. Terminology
-
- The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
- "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
- document are to be interpreted as described in [RFC2119].
-
- This document is concerned with the portion of a mail message
- commonly called "envelope sender", "return path", "reverse path",
- "bounce address", "2821 FROM", or "MAIL FROM". Since these terms are
- either not well defined or often used casually, this document defines
- the "MAIL FROM" identity in Section 2.2. Note that other terms that
- may superficially look like the common terms, such as "reverse-path",
- are used only with the defined meanings from normative documents.
-
-2. Operation
-
-2.1. The HELO Identity
-
- The "HELO" identity derives from either the SMTP HELO or EHLO command
- (see [RFC2821]). These commands supply the SMTP client (sending
- host) for the SMTP session. Note that requirements for the domain
- presented in the EHLO or HELO command are not always clear to the
- sending party, and SPF clients must be prepared for the "HELO"
- identity to be malformed or an IP address literal. At the time of
- this writing, many legitimate E-Mails are delivered with invalid HELO
- domains.
-
- It is RECOMMENDED that SPF clients not only check the "MAIL FROM"
- identity, but also separately check the "HELO" identity by applying
- the check_host() function (Section 4) to the "HELO" identity as the
- <sender>.
-
-2.2. The MAIL FROM Identity
-
- The "MAIL FROM" identity derives from the SMTP MAIL command (see
- [RFC2821]). This command supplies the "reverse-path" for a message,
- which generally consists of the sender mailbox, and is the mailbox to
- which notification messages are to be sent if there are problems
- delivering the message.
-
- [RFC2821] allows the reverse-path to be null (see Section 4.5.5 in
- RFC 2821). In this case, there is no explicit sender mailbox, and
- such a message can be assumed to be a notification message from the
- mail system itself. When the reverse-path is null, this document
-
-
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-
- defines the "MAIL FROM" identity to be the mailbox composed of the
- localpart "postmaster" and the "HELO" identity (which may or may not
- have been checked separately before).
-
- SPF clients MUST check the "MAIL FROM" identity. SPF clients check
- the "MAIL FROM" identity by applying the check_host() function to the
- "MAIL FROM" identity as the <sender>.
-
-2.3. Publishing Authorization
-
- An SPF-compliant domain MUST publish a valid SPF record as described
- in Section 3. This record authorizes the use of the domain name in
- the "HELO" and "MAIL FROM" identities by the MTAs it specifies.
-
- If domain owners choose to publish SPF records, it is RECOMMENDED
- that they end in "-all", or redirect to other records that do, so
- that a definitive determination of authorization can be made.
-
- Domain holders may publish SPF records that explicitly authorize no
- hosts if mail should never originate using that domain.
-
- When changing SPF records, care must be taken to ensure that there is
- a transition period so that the old policy remains valid until all
- legitimate E-Mail has been checked.
-
-2.4. Checking Authorization
-
- A mail receiver can perform a set of SPF checks for each mail message
- it receives. An SPF check tests the authorization of a client host
- to emit mail with a given identity. Typically, such checks are done
- by a receiving MTA, but can be performed elsewhere in the mail
- processing chain so long as the required information is available and
- reliable. At least the "MAIL FROM" identity MUST be checked, but it
- is RECOMMENDED that the "HELO" identity also be checked beforehand.
-
- Without explicit approval of the domain owner, checking other
- identities against SPF version 1 records is NOT RECOMMENDED because
- there are cases that are known to give incorrect results. For
- example, almost all mailing lists rewrite the "MAIL FROM" identity
- (see Section 9.2), but some do not change any other identities in the
- message. The scenario described in Section 9.3, sub-section 1.2, is
- another example. Documents that define other identities should
- define the method for explicit approval.
-
- It is possible that mail receivers will use the SPF check as part of
- a larger set of tests on incoming mail. The results of other tests
- may influence whether or not a particular SPF check is performed.
- For example, finding the sending host's IP address on a local white
-
-
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- list may cause all other tests to be skipped and all mail from that
- host to be accepted.
-
- When a mail receiver decides to perform an SPF check, it MUST use a
- correctly-implemented check_host() function (Section 4) evaluated
- with the correct parameters. Although the test as a whole is
- optional, once it has been decided to perform a test it must be
- performed as specified so that the correct semantics are preserved
- between publisher and receiver.
-
- To make the test, the mail receiver MUST evaluate the check_host()
- function with the arguments set as follows:
-
- <ip> - the IP address of the SMTP client that is emitting the
- mail, either IPv4 or IPv6.
-
- <domain> - the domain portion of the "MAIL FROM" or "HELO" identity.
-
- <sender> - the "MAIL FROM" or "HELO" identity.
-
- Note that the <domain> argument may not be a well-formed domain name.
- For example, if the reverse-path was null, then the EHLO/HELO domain
- is used, with its associated problems (see Section 2.1). In these
- cases, check_host() is defined in Section 4.3 to return a "None"
- result.
-
- Although invalid, malformed, or non-existent domains cause SPF checks
- to return "None" because no SPF record can be found, it has long been
- the policy of many MTAs to reject E-Mail from such domains,
- especially in the case of invalid "MAIL FROM". In order to prevent
- the circumvention of SPF records, rejecting E-Mail from invalid
- domains should be considered.
-
- Implementations must take care to correctly extract the <domain> from
- the data given with the SMTP MAIL FROM command as many MTAs will
- still accept such things as source routes (see [RFC2821], Appendix
- C), the %-hack (see [RFC1123]), and bang paths (see [RFC1983]).
- These archaic features have been maliciously used to bypass security
- systems.
-
-2.5. Interpreting the Result
-
- This section describes how software that performs the authorization
- should interpret the results of the check_host() function. The
- authorization check SHOULD be performed during the processing of the
- SMTP transaction that sends the mail. This allows errors to be
- returned directly to the sending MTA by way of SMTP replies.
-
-
-
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-
- Performing the authorization after the SMTP transaction has finished
- may cause problems, such as the following: (1) It may be difficult to
- accurately extract the required information from potentially
- deceptive headers; (2) legitimate E-Mail may fail because the
- sender's policy may have since changed.
-
- Generating non-delivery notifications to forged identities that have
- failed the authorization check is generally abusive and against the
- explicit wishes of the identity owner.
-
-2.5.1. None
-
- A result of "None" means that no records were published by the domain
- or that no checkable sender domain could be determined from the given
- identity. The checking software cannot ascertain whether or not the
- client host is authorized.
-
-2.5.2. Neutral
-
- The domain owner has explicitly stated that he cannot or does not
- want to assert whether or not the IP address is authorized. A
- "Neutral" result MUST be treated exactly like the "None" result; the
- distinction exists only for informational purposes. Treating
- "Neutral" more harshly than "None" would discourage domain owners
- from testing the use of SPF records (see Section 9.1).
-
-2.5.3. Pass
-
- A "Pass" result means that the client is authorized to inject mail
- with the given identity. The domain can now, in the sense of
- reputation, be considered responsible for sending the message.
- Further policy checks can now proceed with confidence in the
- legitimate use of the identity.
-
-2.5.4. Fail
-
- A "Fail" result is an explicit statement that the client is not
- authorized to use the domain in the given identity. The checking
- software can choose to mark the mail based on this or to reject the
- mail outright.
-
- If the checking software chooses to reject the mail during the SMTP
- transaction, then it SHOULD use an SMTP reply code of 550 (see
- [RFC2821]) and, if supported, the 5.7.1 Delivery Status Notification
- (DSN) code (see [RFC3464]), in addition to an appropriate reply text.
- The check_host() function may return either a default explanation
- string or one from the domain that published the SPF records (see
- Section 6.2). If the information does not originate with the
-
-
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-
- checking software, it should be made clear that the text is provided
- by the sender's domain. For example:
-
- 550-5.7.1 SPF MAIL FROM check failed:
- 550-5.7.1 The domain example.com explains:
- 550 5.7.1 Please see http://www.example.com/mailpolicy.html
-
-2.5.5. SoftFail
-
- A "SoftFail" result should be treated as somewhere between a "Fail"
- and a "Neutral". The domain believes the host is not authorized but
- is not willing to make that strong of a statement. Receiving
- software SHOULD NOT reject the message based solely on this result,
- but MAY subject the message to closer scrutiny than normal.
-
- The domain owner wants to discourage the use of this host and thus
- desires limited feedback when a "SoftFail" result occurs. For
- example, the recipient's Mail User Agent (MUA) could highlight the
- "SoftFail" status, or the receiving MTA could give the sender a
- message using a technique called "greylisting" whereby the MTA can
- issue an SMTP reply code of 451 (4.3.0 DSN code) with a note the
- first time the message is received, but accept it the second time.
-
-2.5.6. TempError
-
- A "TempError" result means that the SPF client encountered a
- transient error while performing the check. Checking software can
- choose to accept or temporarily reject the message. If the message
- is rejected during the SMTP transaction for this reason, the software
- SHOULD use an SMTP reply code of 451 and, if supported, the 4.4.3 DSN
- code.
-
-2.5.7. PermError
-
- A "PermError" result means that the domain's published records could
- not be correctly interpreted. This signals an error condition that
- requires manual intervention to be resolved, as opposed to the
- TempError result. Be aware that if the domain owner uses macros
- (Section 8), it is possible that this result is due to the checked
- identities having an unexpected format.
-
-3. SPF Records
-
- An SPF record is a DNS Resource Record (RR) that declares which hosts
- are, and are not, authorized to use a domain name for the "HELO" and
- "MAIL FROM" identities. Loosely, the record partitions all hosts
- into permitted and not-permitted sets (though some hosts might fall
- into neither category).
-
-
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-
- The SPF record is a single string of text. An example record is the
- following:
-
- v=spf1 +mx a:colo.example.com/28 -all
-
- This record has a version of "spf1" and three directives: "+mx",
- "a:colo.example.com/28" (the + is implied), and "-all".
-
-3.1. Publishing
-
- Domain owners wishing to be SPF compliant must publish SPF records
- for the hosts that are used in the "MAIL FROM" and "HELO" identities.
- The SPF records are placed in the DNS tree at the host name it
- pertains to, not a subdomain under it, such as is done with SRV
- records. This is the same whether the TXT or SPF RR type (see
- Section 3.1.1) is used.
-
- The example above in Section 3 might be published via these lines in
- a domain zone file:
-
- example.com. TXT "v=spf1 +mx a:colo.example.com/28 -all"
- smtp-out.example.com. TXT "v=spf1 a -all"
-
- When publishing via TXT records, beware of other TXT records
- published there for other purposes. They may cause problems with
- size limits (see Section 3.1.4).
-
-3.1.1. DNS Resource Record Types
-
- This document defines a new DNS RR of type SPF, code 99. The format
- of this type is identical to the TXT RR [RFC1035]. For either type,
- the character content of the record is encoded as [US-ASCII].
-
- It is recognized that the current practice (using a TXT record) is
- not optimal, but it is necessary because there are a number of DNS
- server and resolver implementations in common use that cannot handle
- the new RR type. The two-record-type scheme provides a forward path
- to the better solution of using an RR type reserved for this purpose.
-
- An SPF-compliant domain name SHOULD have SPF records of both RR
- types. A compliant domain name MUST have a record of at least one
- type. If a domain has records of both types, they MUST have
- identical content. For example, instead of publishing just one
- record as in Section 3.1 above, it is better to publish:
-
- example.com. IN TXT "v=spf1 +mx a:colo.example.com/28 -all"
- example.com. IN SPF "v=spf1 +mx a:colo.example.com/28 -all"
-
-
-
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-
- Example RRs in this document are shown with the TXT record type;
- however, they could be published with the SPF type or with both
- types.
-
-3.1.2. Multiple DNS Records
-
- A domain name MUST NOT have multiple records that would cause an
- authorization check to select more than one record. See Section 4.5
- for the selection rules.
-
-3.1.3. Multiple Strings in a Single DNS record
-
- As defined in [RFC1035] sections 3.3.14 and 3.3, a single text DNS
- record (either TXT or SPF RR types) can be composed of more than one
- string. If a published record contains multiple strings, then the
- record MUST be treated as if those strings are concatenated together
- without adding spaces. For example:
-
- IN TXT "v=spf1 .... first" "second string..."
-
- MUST be treated as equivalent to
-
- IN TXT "v=spf1 .... firstsecond string..."
-
- SPF or TXT records containing multiple strings are useful in
- constructing records that would exceed the 255-byte maximum length of
- a string within a single TXT or SPF RR record.
-
-3.1.4. Record Size
-
- The published SPF record for a given domain name SHOULD remain small
- enough that the results of a query for it will fit within 512 octets.
- This will keep even older DNS implementations from falling over to
- TCP. Since the answer size is dependent on many things outside the
- scope of this document, it is only possible to give this guideline:
- If the combined length of the DNS name and the text of all the
- records of a given type (TXT or SPF) is under 450 characters, then
- DNS answers should fit in UDP packets. Note that when computing the
- sizes for queries of the TXT format, one must take into account any
- other TXT records published at the domain name. Records that are too
- long to fit in a single UDP packet MAY be silently ignored by SPF
- clients.
-
-3.1.5. Wildcard Records
-
- Use of wildcard records for publishing is not recommended. Care must
- be taken if wildcard records are used. If a domain publishes
- wildcard MX records, it may want to publish wildcard declarations,
-
-
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-
- subject to the same requirements and problems. In particular, the
- declaration must be repeated for any host that has any RR records at
- all, and for subdomains thereof. For example, the example given in
- [RFC1034], Section 4.3.3, could be extended with the following:
-
- X.COM. MX 10 A.X.COM
- X.COM. TXT "v=spf1 a:A.X.COM -all"
-
- *.X.COM. MX 10 A.X.COM
- *.X.COM. TXT "v=spf1 a:A.X.COM -all"
-
- A.X.COM. A 1.2.3.4
- A.X.COM. MX 10 A.X.COM
- A.X.COM. TXT "v=spf1 a:A.X.COM -all"
-
- *.A.X.COM. MX 10 A.X.COM
- *.A.X.COM. TXT "v=spf1 a:A.X.COM -all"
-
- Notice that SPF records must be repeated twice for every name within
- the domain: once for the name, and once with a wildcard to cover the
- tree under the name.
-
- Use of wildcards is discouraged in general as they cause every name
- under the domain to exist and queries against arbitrary names will
- never return RCODE 3 (Name Error).
-
-4. The check_host() Function
-
- The check_host() function fetches SPF records, parses them, and
- interprets them to determine whether a particular host is or is not
- permitted to send mail with a given identity. Mail receivers that
- perform this check MUST correctly evaluate the check_host() function
- as described here.
-
- Implementations MAY use a different algorithm than the canonical
- algorithm defined here, so long as the results are the same in all
- cases.
-
-4.1. Arguments
-
- The check_host() function takes these arguments:
-
- <ip> - the IP address of the SMTP client that is emitting the
- mail, either IPv4 or IPv6.
-
- <domain> - the domain that provides the sought-after authorization
- information; initially, the domain portion of the "MAIL
- FROM" or "HELO" identity.
-
-
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-
- <sender> - the "MAIL FROM" or "HELO" identity.
-
- The domain portion of <sender> will usually be the same as the
- <domain> argument when check_host() is initially evaluated. However,
- this will generally not be true for recursive evaluations (see
- Section 5.2 below).
-
- Actual implementations of the check_host() function may need
- additional arguments.
-
-4.2. Results
-
- The function check_host() can return one of several results described
- in Section 2.5. Based on the result, the action to be taken is
- determined by the local policies of the receiver.
-
-4.3. Initial Processing
-
- If the <domain> is malformed (label longer than 63 characters, zero-
- length label not at the end, etc.) or is not a fully qualified domain
- name, or if the DNS lookup returns "domain does not exist" (RCODE 3),
- check_host() immediately returns the result "None".
-
- If the <sender> has no localpart, substitute the string "postmaster"
- for the localpart.
-
-4.4. Record Lookup
-
- In accordance with how the records are published (see Section 3.1
- above), a DNS query needs to be made for the <domain> name, querying
- for either RR type TXT, SPF, or both. If both SPF and TXT RRs are
- looked up, the queries MAY be done in parallel.
-
- If all DNS lookups that are made return a server failure (RCODE 2),
- or other error (RCODE other than 0 or 3), or time out, then
- check_host() exits immediately with the result "TempError".
-
-4.5. Selecting Records
-
- Records begin with a version section:
-
- record = version terms *SP
- version = "v=spf1"
-
- Starting with the set of records that were returned by the lookup,
- record selection proceeds in two steps:
-
-
-
-
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-
- 1. Records that do not begin with a version section of exactly
- "v=spf1" are discarded. Note that the version section is
- terminated either by an SP character or the end of the record. A
- record with a version section of "v=spf10" does not match and must
- be discarded.
-
- 2. If any records of type SPF are in the set, then all records of
- type TXT are discarded.
-
- After the above steps, there should be exactly one record remaining
- and evaluation can proceed. If there are two or more records
- remaining, then check_host() exits immediately with the result of
- "PermError".
-
- If no matching records are returned, an SPF client MUST assume that
- the domain makes no SPF declarations. SPF processing MUST stop and
- return "None".
-
-4.6. Record Evaluation
-
- After one SPF record has been selected, the check_host() function
- parses and interprets it to find a result for the current test. If
- there are any syntax errors, check_host() returns immediately with
- the result "PermError".
-
- Implementations MAY choose to parse the entire record first and
- return "PermError" if the record is not syntactically well formed.
- However, in all cases, any syntax errors anywhere in the record MUST
- be detected.
-
-4.6.1. Term Evaluation
-
- There are two types of terms: mechanisms and modifiers. A record
- contains an ordered list of these as specified in the following
- Augmented Backus-Naur Form (ABNF).
-
- terms = *( 1*SP ( directive / modifier ) )
-
- directive = [ qualifier ] mechanism
- qualifier = "+" / "-" / "?" / "~"
- mechanism = ( all / include
- / A / MX / PTR / IP4 / IP6 / exists )
- modifier = redirect / explanation / unknown-modifier
- unknown-modifier = name "=" macro-string
-
- name = ALPHA *( ALPHA / DIGIT / "-" / "_" / "." )
-
- Most mechanisms allow a ":" or "/" character after the name.
-
-
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-
- Modifiers always contain an equals ('=') character immediately after
- the name, and before any ":" or "/" characters that may be part of
- the macro-string.
-
- Terms that do not contain any of "=", ":", or "/" are mechanisms, as
- defined in Section 5.
-
- As per the definition of the ABNF notation in [RFC4234], mechanism
- and modifier names are case-insensitive.
-
-4.6.2. Mechanisms
-
- Each mechanism is considered in turn from left to right. If there
- are no more mechanisms, the result is specified in Section 4.7.
-
- When a mechanism is evaluated, one of three things can happen: it can
- match, not match, or throw an exception.
-
- If it matches, processing ends and the qualifier value is returned as
- the result of that record. If it does not match, processing
- continues with the next mechanism. If it throws an exception,
- mechanism processing ends and the exception value is returned.
-
- The possible qualifiers, and the results they return are as follows:
-
- "+" Pass
- "-" Fail
- "~" SoftFail
- "?" Neutral
-
- The qualifier is optional and defaults to "+".
-
- When a mechanism matches and the qualifier is "-", then a "Fail"
- result is returned and the explanation string is computed as
- described in Section 6.2.
-
- The specific mechanisms are described in Section 5.
-
-4.6.3. Modifiers
-
- Modifiers are not mechanisms: they do not return match or not-match.
- Instead they provide additional information. Although modifiers do
- not directly affect the evaluation of the record, the "redirect"
- modifier has an effect after all the mechanisms have been evaluated.
-
-
-
-
-
-
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-
-4.7. Default Result
-
- If none of the mechanisms match and there is no "redirect" modifier,
- then the check_host() returns a result of "Neutral", just as if
- "?all" were specified as the last directive. If there is a
- "redirect" modifier, check_host() proceeds as defined in Section 6.1.
-
- Note that records SHOULD always use either a "redirect" modifier or
- an "all" mechanism to explicitly terminate processing.
-
- For example:
-
- v=spf1 +mx -all
- or
- v=spf1 +mx redirect=_spf.example.com
-
-4.8. Domain Specification
-
- Several of these mechanisms and modifiers have a <domain-spec>
- section. The <domain-spec> string is macro expanded (see Section 8).
- The resulting string is the common presentation form of a fully-
- qualified DNS name: a series of labels separated by periods. This
- domain is called the <target-name> in the rest of this document.
-
- Note: The result of the macro expansion is not subject to any further
- escaping. Hence, this facility cannot produce all characters that
- are legal in a DNS label (e.g., the control characters). However,
- this facility is powerful enough to express legal host names and
- common utility labels (such as "_spf") that are used in DNS.
-
- For several mechanisms, the <domain-spec> is optional. If it is not
- provided, the <domain> is used as the <target-name>.
-
-5. Mechanism Definitions
-
- This section defines two types of mechanisms.
-
- Basic mechanisms contribute to the language framework. They do not
- specify a particular type of authorization scheme.
-
- all
- include
-
- Designated sender mechanisms are used to designate a set of <ip>
- addresses as being permitted or not permitted to use the <domain> for
- sending mail.
-
-
-
-
-
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-
-
- a
- mx
- ptr
- ip4
- ip6
- exists
-
- The following conventions apply to all mechanisms that perform a
- comparison between <ip> and an IP address at any point:
-
- If no CIDR-length is given in the directive, then <ip> and the IP
- address are compared for equality. (Here, CIDR is Classless Inter-
- Domain Routing.)
-
- If a CIDR-length is specified, then only the specified number of
- high-order bits of <ip> and the IP address are compared for equality.
-
- When any mechanism fetches host addresses to compare with <ip>, when
- <ip> is an IPv4 address, A records are fetched, when <ip> is an IPv6
- address, AAAA records are fetched. Even if the SMTP connection is
- via IPv6, an IPv4-mapped IPv6 IP address (see [RFC3513], Section
- 2.5.5) MUST still be considered an IPv4 address.
-
- Several mechanisms rely on information fetched from DNS. For these
- DNS queries, except where noted, if the DNS server returns an error
- (RCODE other than 0 or 3) or the query times out, the mechanism
- throws the exception "TempError". If the server returns "domain does
- not exist" (RCODE 3), then evaluation of the mechanism continues as
- if the server returned no error (RCODE 0) and zero answer records.
-
-5.1. "all"
-
- all = "all"
-
- The "all" mechanism is a test that always matches. It is used as the
- rightmost mechanism in a record to provide an explicit default.
-
- For example:
-
- v=spf1 a mx -all
-
- Mechanisms after "all" will never be tested. Any "redirect" modifier
- (Section 6.1) has no effect when there is an "all" mechanism.
-
-
-
-
-
-
-
-
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-
-
-5.2. "include"
-
- include = "include" ":" domain-spec
-
- The "include" mechanism triggers a recursive evaluation of
- check_host(). The domain-spec is expanded as per Section 8. Then
- check_host() is evaluated with the resulting string as the <domain>.
- The <ip> and <sender> arguments remain the same as in the current
- evaluation of check_host().
-
- In hindsight, the name "include" was poorly chosen. Only the
- evaluated result of the referenced SPF record is used, rather than
- acting as if the referenced SPF record was literally included in the
- first. For example, evaluating a "-all" directive in the referenced
- record does not terminate the overall processing and does not
- necessarily result in an overall "Fail". (Better names for this
- mechanism would have been "if-pass", "on-pass", etc.)
-
- The "include" mechanism makes it possible for one domain to designate
- multiple administratively-independent domains. For example, a vanity
- domain "example.net" might send mail using the servers of
- administratively-independent domains example.com and example.org.
-
- Example.net could say
-
- IN TXT "v=spf1 include:example.com include:example.org -all"
-
- This would direct check_host() to, in effect, check the records of
- example.com and example.org for a "Pass" result. Only if the host
- were not permitted for either of those domains would the result be
- "Fail".
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
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-
-
- Whether this mechanism matches, does not match, or throws an
- exception depends on the result of the recursive evaluation of
- check_host():
-
- +---------------------------------+---------------------------------+
- | A recursive check_host() result | Causes the "include" mechanism |
- | of: | to: |
- +---------------------------------+---------------------------------+
- | Pass | match |
- | | |
- | Fail | not match |
- | | |
- | SoftFail | not match |
- | | |
- | Neutral | not match |
- | | |
- | TempError | throw TempError |
- | | |
- | PermError | throw PermError |
- | | |
- | None | throw PermError |
- +---------------------------------+---------------------------------+
-
- The "include" mechanism is intended for crossing administrative
- boundaries. Although it is possible to use includes to consolidate
- multiple domains that share the same set of designated hosts, domains
- are encouraged to use redirects where possible, and to minimize the
- number of includes within a single administrative domain. For
- example, if example.com and example.org were managed by the same
- entity, and if the permitted set of hosts for both domains was
- "mx:example.com", it would be possible for example.org to specify
- "include:example.com", but it would be preferable to specify
- "redirect=example.com" or even "mx:example.com".
-
-5.3. "a"
-
- This mechanism matches if <ip> is one of the <target-name>'s IP
- addresses.
-
- A = "a" [ ":" domain-spec ] [ dual-cidr-length ]
-
- An address lookup is done on the <target-name>. The <ip> is compared
- to the returned address(es). If any address matches, the mechanism
- matches.
-
-
-
-
-
-
-
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-
-
-5.4. "mx"
-
- This mechanism matches if <ip> is one of the MX hosts for a domain
- name.
-
- MX = "mx" [ ":" domain-spec ] [ dual-cidr-length ]
-
- check_host() first performs an MX lookup on the <target-name>. Then
- it performs an address lookup on each MX name returned. The <ip> is
- compared to each returned IP address. To prevent Denial of Service
- (DoS) attacks, more than 10 MX names MUST NOT be looked up during the
- evaluation of an "mx" mechanism (see Section 10). If any address
- matches, the mechanism matches.
-
- Note regarding implicit MXs: If the <target-name> has no MX records,
- check_host() MUST NOT pretend the target is its single MX, and MUST
- NOT default to an A lookup on the <target-name> directly. This
- behavior breaks with the legacy "implicit MX" rule. See [RFC2821],
- Section 5. If such behavior is desired, the publisher should specify
- an "a" directive.
-
-5.5. "ptr"
-
- This mechanism tests whether the DNS reverse-mapping for <ip> exists
- and correctly points to a domain name within a particular domain.
-
- PTR = "ptr" [ ":" domain-spec ]
-
- First, the <ip>'s name is looked up using this procedure: perform a
- DNS reverse-mapping for <ip>, looking up the corresponding PTR record
- in "in-addr.arpa." if the address is an IPv4 one and in "ip6.arpa."
- if it is an IPv6 address. For each record returned, validate the
- domain name by looking up its IP address. To prevent DoS attacks,
- more than 10 PTR names MUST NOT be looked up during the evaluation of
- a "ptr" mechanism (see Section 10). If <ip> is among the returned IP
- addresses, then that domain name is validated. In pseudocode:
-
- sending-domain_names := ptr_lookup(sending-host_IP); if more than 10
- sending-domain_names are found, use at most 10. for each name in
- (sending-domain_names) {
- IP_addresses := a_lookup(name);
- if the sending-domain_IP is one of the IP_addresses {
- validated-sending-domain_names += name;
- } }
-
- Check all validated domain names to see if they end in the
- <target-name> domain. If any do, this mechanism matches. If no
- validated domain name can be found, or if none of the validated
-
-
-
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-
-
- domain names end in the <target-name>, this mechanism fails to match.
- If a DNS error occurs while doing the PTR RR lookup, then this
- mechanism fails to match. If a DNS error occurs while doing an A RR
- lookup, then that domain name is skipped and the search continues.
-
- Pseudocode:
-
- for each name in (validated-sending-domain_names) {
- if name ends in <domain-spec>, return match.
- if name is <domain-spec>, return match.
- }
- return no-match.
-
- This mechanism matches if the <target-name> is either an ancestor of
- a validated domain name or if the <target-name> and a validated
- domain name are the same. For example: "mail.example.com" is within
- the domain "example.com", but "mail.bad-example.com" is not.
-
- Note: Use of this mechanism is discouraged because it is slow, it is
- not as reliable as other mechanisms in cases of DNS errors, and it
- places a large burden on the arpa name servers. If used, proper PTR
- records must be in place for the domain's hosts and the "ptr"
- mechanism should be one of the last mechanisms checked.
-
-5.6. "ip4" and "ip6"
-
- These mechanisms test whether <ip> is contained within a given IP
- network.
-
- IP4 = "ip4" ":" ip4-network [ ip4-cidr-length ]
- IP6 = "ip6" ":" ip6-network [ ip6-cidr-length ]
-
- ip4-cidr-length = "/" 1*DIGIT
- ip6-cidr-length = "/" 1*DIGIT
- dual-cidr-length = [ ip4-cidr-length ] [ "/" ip6-cidr-length ]
-
- ip4-network = qnum "." qnum "." qnum "." qnum
- qnum = DIGIT ; 0-9
- / %x31-39 DIGIT ; 10-99
- / "1" 2DIGIT ; 100-199
- / "2" %x30-34 DIGIT ; 200-249
- / "25" %x30-35 ; 250-255
- ; as per conventional dotted quad notation. e.g., 192.0.2.0
- ip6-network = <as per [RFC 3513], section 2.2>
- ; e.g., 2001:DB8::CD30
-
- The <ip> is compared to the given network. If CIDR-length high-order
- bits match, the mechanism matches.
-
-
-
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-
-
- If ip4-cidr-length is omitted, it is taken to be "/32". If
- ip6-cidr-length is omitted, it is taken to be "/128". It is not
- permitted to omit parts of the IP address instead of using CIDR
- notations. That is, use 192.0.2.0/24 instead of 192.0.2.
-
-5.7. "exists"
-
- This mechanism is used to construct an arbitrary domain name that is
- used for a DNS A record query. It allows for complicated schemes
- involving arbitrary parts of the mail envelope to determine what is
- permitted.
-
- exists = "exists" ":" domain-spec
-
- The domain-spec is expanded as per Section 8. The resulting domain
- name is used for a DNS A RR lookup. If any A record is returned,
- this mechanism matches. The lookup type is A even when the
- connection type is IPv6.
-
- Domains can use this mechanism to specify arbitrarily complex
- queries. For example, suppose example.com publishes the record:
-
- v=spf1 exists:%{ir}.%{l1r+-}._spf.%{d} -all
-
- The <target-name> might expand to
- "1.2.0.192.someuser._spf.example.com". This makes fine-grained
- decisions possible at the level of the user and client IP address.
-
- This mechanism enables queries that mimic the style of tests that
- existing anti-spam DNS blacklists (DNSBL) use.
-
-6. Modifier Definitions
-
- Modifiers are name/value pairs that provide additional information.
- Modifiers always have an "=" separating the name and the value.
-
- The modifiers defined in this document ("redirect" and "exp") MAY
- appear anywhere in the record, but SHOULD appear at the end, after
- all mechanisms. Ordering of these two modifiers does not matter.
- These two modifiers MUST NOT appear in a record more than once each.
- If they do, then check_host() exits with a result of "PermError".
-
- Unrecognized modifiers MUST be ignored no matter where in a record,
- or how often. This allows implementations of this document to
- gracefully handle records with modifiers that are defined in other
- specifications.
-
-
-
-
-
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-
-
-6.1. redirect: Redirected Query
-
- If all mechanisms fail to match, and a "redirect" modifier is
- present, then processing proceeds as follows:
-
- redirect = "redirect" "=" domain-spec
-
- The domain-spec portion of the redirect section is expanded as per
- the macro rules in Section 8. Then check_host() is evaluated with
- the resulting string as the <domain>. The <ip> and <sender>
- arguments remain the same as current evaluation of check_host().
-
- The result of this new evaluation of check_host() is then considered
- the result of the current evaluation with the exception that if no
- SPF record is found, or if the target-name is malformed, the result
- is a "PermError" rather than "None".
-
- Note that the newly-queried domain may itself specify redirect
- processing.
-
- This facility is intended for use by organizations that wish to apply
- the same record to multiple domains. For example:
-
- la.example.com. TXT "v=spf1 redirect=_spf.example.com"
- ny.example.com. TXT "v=spf1 redirect=_spf.example.com"
- sf.example.com. TXT "v=spf1 redirect=_spf.example.com"
- _spf.example.com. TXT "v=spf1 mx:example.com -all"
-
- In this example, mail from any of the three domains is described by
- the same record. This can be an administrative advantage.
-
- Note: In general, the domain "A" cannot reliably use a redirect to
- another domain "B" not under the same administrative control. Since
- the <sender> stays the same, there is no guarantee that the record at
- domain "B" will correctly work for mailboxes in domain "A",
- especially if domain "B" uses mechanisms involving localparts. An
- "include" directive may be more appropriate.
-
- For clarity, it is RECOMMENDED that any "redirect" modifier appear as
- the very last term in a record.
-
-6.2. exp: Explanation
-
- explanation = "exp" "=" domain-spec
-
- If check_host() results in a "Fail" due to a mechanism match (such as
- "-all"), and the "exp" modifier is present, then the explanation
- string returned is computed as described below. If no "exp" modifier
-
-
-
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-
-
- is present, then either a default explanation string or an empty
- explanation string may be returned.
-
- The <domain-spec> is macro expanded (see Section 8) and becomes the
- <target-name>. The DNS TXT record for the <target-name> is fetched.
-
- If <domain-spec> is empty, or there are any DNS processing errors
- (any RCODE other than 0), or if no records are returned, or if more
- than one record is returned, or if there are syntax errors in the
- explanation string, then proceed as if no exp modifier was given.
-
- The fetched TXT record's strings are concatenated with no spaces, and
- then treated as an <explain-string>, which is macro-expanded. This
- final result is the explanation string. Implementations MAY limit
- the length of the resulting explanation string to allow for other
- protocol constraints and/or reasonable processing limits. Since the
- explanation string is intended for an SMTP response and [RFC2821]
- Section 2.4 says that responses are in [US-ASCII], the explanation
- string is also limited to US-ASCII.
-
- Software evaluating check_host() can use this string to communicate
- information from the publishing domain in the form of a short message
- or URL. Software SHOULD make it clear that the explanation string
- comes from a third party. For example, it can prepend the macro
- string "%{o} explains: " to the explanation, such as shown in Section
- 2.5.4.
-
- Suppose example.com has this record:
-
- v=spf1 mx -all exp=explain._spf.%{d}
-
- Here are some examples of possible explanation TXT records at
- explain._spf.example.com:
-
- "Mail from example.com should only be sent by its own servers."
- -- a simple, constant message
-
- "%{i} is not one of %{d}'s designated mail servers."
- -- a message with a little more information, including the IP
- address that failed the check
-
- "See http://%{d}/why.html?s=%{S}&i=%{I}"
- -- a complicated example that constructs a URL with the
- arguments to check_host() so that a web page can be
- generated with detailed, custom instructions
-
- Note: During recursion into an "include" mechanism, an exp= modifier
- from the <target-name> MUST NOT be used. In contrast, when executing
-
-
-
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-
-
- a "redirect" modifier, an exp= modifier from the original domain MUST
- NOT be used.
-
-7. The Received-SPF Header Field
-
- It is RECOMMENDED that SMTP receivers record the result of SPF
- processing in the message header. If an SMTP receiver chooses to do
- so, it SHOULD use the "Received-SPF" header field defined here for
- each identity that was checked. This information is intended for the
- recipient. (Information intended for the sender is described in
- Section 6.2, Explanation.)
-
- The Received-SPF header field is a trace field (see [RFC2822] Section
- 3.6.7) and SHOULD be prepended to the existing header, above the
- Received: field that is generated by the SMTP receiver. It MUST
- appear above all other Received-SPF fields in the message. The
- header field has the following format:
-
- header-field = "Received-SPF:" [CFWS] result FWS [comment FWS]
- [ key-value-list ] CRLF
-
- result = "Pass" / "Fail" / "SoftFail" / "Neutral" /
- "None" / "TempError" / "PermError"
-
- key-value-list = key-value-pair *( ";" [CFWS] key-value-pair )
- [";"]
-
- key-value-pair = key [CFWS] "=" ( dot-atom / quoted-string )
-
- key = "client-ip" / "envelope-from" / "helo" /
- "problem" / "receiver" / "identity" /
- mechanism / "x-" name / name
-
- identity = "mailfrom" ; for the "MAIL FROM" identity
- / "helo" ; for the "HELO" identity
- / name ; other identities
-
- dot-atom = <unquoted word as per [RFC2822]>
- quoted-string = <quoted string as per [RFC2822]>
- comment = <comment string as per [RFC2822]>
- CFWS = <comment or folding white space as per [RFC2822]>
- FWS = <folding white space as per [RFC2822]>
- CRLF = <standard end-of-line token as per [RFC2822]>
-
- The header field SHOULD include a "(...)" style <comment> after the
- result, conveying supporting information for the result, such as
- <ip>, <sender>, and <domain>.
-
-
-
-
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-
-
- The following key-value pairs are designed for later machine parsing.
- SPF clients SHOULD give enough information so that the SPF results
- can be verified. That is, at least "client-ip", "helo", and, if the
- "MAIL FROM" identity was checked, "envelope-from".
-
- client-ip the IP address of the SMTP client
-
- envelope-from the envelope sender mailbox
-
- helo the host name given in the HELO or EHLO command
-
- mechanism the mechanism that matched (if no mechanisms matched,
- substitute the word "default")
-
- problem if an error was returned, details about the error
-
- receiver the host name of the SPF client
-
- identity the identity that was checked; see the <identity> ABNF
- rule
-
- Other keys may be defined by SPF clients. Until a new key name
- becomes widely accepted, new key names should start with "x-".
-
- SPF clients MUST make sure that the Received-SPF header field does
- not contain invalid characters, is not excessively long, and does not
- contain malicious data that has been provided by the sender.
-
- Examples of various header styles that could be generated are the
- following:
-
- Received-SPF: Pass (mybox.example.org: domain of
- myname@example.com designates 192.0.2.1 as permitted sender)
- receiver=mybox.example.org; client-ip=192.0.2.1;
- envelope-from=<myname@example.com>; helo=foo.example.com;
-
- Received-SPF: Fail (mybox.example.org: domain of
- myname@example.com does not designate
- 192.0.2.1 as permitted sender)
- identity=mailfrom; client-ip=192.0.2.1;
- envelope-from=<myname@example.com>;
-
-
-
-
-
-
-
-
-
-
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-
-
-8. Macros
-
-8.1. Macro Definitions
-
- Many mechanisms and modifiers perform macro expansion on part of the
- term.
-
- domain-spec = macro-string domain-end
- domain-end = ( "." toplabel [ "." ] ) / macro-expand
-
- toplabel = ( *alphanum ALPHA *alphanum ) /
- ( 1*alphanum "-" *( alphanum / "-" ) alphanum )
- ; LDH rule plus additional TLD restrictions
- ; (see [RFC3696], Section 2)
- alphanum = ALPHA / DIGIT
-
- explain-string = *( macro-string / SP )
-
- macro-string = *( macro-expand / macro-literal )
- macro-expand = ( "%{" macro-letter transformers *delimiter "}" )
- / "%%" / "%_" / "%-"
- macro-literal = %x21-24 / %x26-7E
- ; visible characters except "%"
- macro-letter = "s" / "l" / "o" / "d" / "i" / "p" / "h" /
- "c" / "r" / "t"
- transformers = *DIGIT [ "r" ]
- delimiter = "." / "-" / "+" / "," / "/" / "_" / "="
-
- A literal "%" is expressed by "%%".
-
- "%_" expands to a single " " space.
- "%-" expands to a URL-encoded space, viz., "%20".
-
- The following macro letters are expanded in term arguments:
-
- s = <sender>
- l = local-part of <sender>
- o = domain of <sender>
- d = <domain>
- i = <ip>
- p = the validated domain name of <ip>
- v = the string "in-addr" if <ip> is ipv4, or "ip6" if <ip> is ipv6
- h = HELO/EHLO domain
-
-
-
-
-
-
-
-
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-
-
- The following macro letters are allowed only in "exp" text:
-
- c = SMTP client IP (easily readable format)
- r = domain name of host performing the check
- t = current timestamp
-
- A '%' character not followed by a '{', '%', '-', or '_' character is
- a syntax error. So
-
- -exists:%(ir).sbl.spamhaus.example.org
-
- is incorrect and will cause check_host() to return a "PermError".
- Instead, say
-
- -exists:%{ir}.sbl.spamhaus.example.org
-
- Optional transformers are the following:
-
- *DIGIT = zero or more digits
- 'r' = reverse value, splitting on dots by default
-
- If transformers or delimiters are provided, the replacement value for
- a macro letter is split into parts. After performing any reversal
- operation and/or removal of left-hand parts, the parts are rejoined
- using "." and not the original splitting characters.
-
- By default, strings are split on "." (dots). Note that no special
- treatment is given to leading, trailing, or consecutive delimiters,
- and so the list of parts may contain empty strings. Older
- implementations of SPF prohibit trailing dots in domain names, so
- trailing dots should not be published by domain owners, although they
- must be accepted by implementations conforming to this document.
- Macros may specify delimiter characters that are used instead of ".".
-
- The 'r' transformer indicates a reversal operation: if the client IP
- address were 192.0.2.1, the macro %{i} would expand to "192.0.2.1"
- and the macro %{ir} would expand to "1.2.0.192".
-
- The DIGIT transformer indicates the number of right-hand parts to
- use, after optional reversal. If a DIGIT is specified, the value
- MUST be nonzero. If no DIGITs are specified, or if the value
- specifies more parts than are available, all the available parts are
- used. If the DIGIT was 5, and only 3 parts were available, the macro
- interpreter would pretend the DIGIT was 3. Implementations MUST
- support at least a value of 128, as that is the maximum number of
- labels in a domain name.
-
-
-
-
-
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-
-
- The "s" macro expands to the <sender> argument. It is an E-Mail
- address with a localpart, an "@" character, and a domain. The "l"
- macro expands to just the localpart. The "o" macro expands to just
- the domain part. Note that these values remain the same during
- recursive and chained evaluations due to "include" and/or "redirect".
- Note also that if the original <sender> had no localpart, the
- localpart was set to "postmaster" in initial processing (see Section
- 4.3).
-
- For IPv4 addresses, both the "i" and "c" macros expand to the
- standard dotted-quad format.
-
- For IPv6 addresses, the "i" macro expands to a dot-format address; it
- is intended for use in %{ir}. The "c" macro may expand to any of the
- hexadecimal colon-format addresses specified in [RFC3513], Section
- 2.2. It is intended for humans to read.
-
- The "p" macro expands to the validated domain name of <ip>. The
- procedure for finding the validated domain name is defined in Section
- 5.5. If the <domain> is present in the list of validated domains, it
- SHOULD be used. Otherwise, if a subdomain of the <domain> is
- present, it SHOULD be used. Otherwise, any name from the list may be
- used. If there are no validated domain names or if a DNS error
- occurs, the string "unknown" is used.
-
- The "r" macro expands to the name of the receiving MTA. This SHOULD
- be a fully qualified domain name, but if one does not exist (as when
- the checking is done by a MUA) or if policy restrictions dictate
- otherwise, the word "unknown" SHOULD be substituted. The domain name
- may be different from the name found in the MX record that the client
- MTA used to locate the receiving MTA.
-
- The "t" macro expands to the decimal representation of the
- approximate number of seconds since the Epoch (Midnight, January 1,
- 1970, UTC). This is the same value as is returned by the POSIX
- time() function in most standards-compliant libraries.
-
- When the result of macro expansion is used in a domain name query, if
- the expanded domain name exceeds 253 characters (the maximum length
- of a domain name), the left side is truncated to fit, by removing
- successive domain labels until the total length does not exceed 253
- characters.
-
- Uppercased macros expand exactly as their lowercased equivalents, and
- are then URL escaped. URL escaping must be performed for characters
- not in the "uric" set, which is defined in [RFC3986].
-
-
-
-
-
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-
-
- Note: Care must be taken so that macro expansion for legitimate
- E-Mail does not exceed the 63-character limit on DNS labels. The
- localpart of E-Mail addresses, in particular, can have more than 63
- characters between dots.
-
- Note: Domains should avoid using the "s", "l", "o", or "h" macros in
- conjunction with any mechanism directive. Although these macros are
- powerful and allow per-user records to be published, they severely
- limit the ability of implementations to cache results of check_host()
- and they reduce the effectiveness of DNS caches.
-
- Implementations should be aware that if no directive processed during
- the evaluation of check_host() contains an "s", "l", "o", or "h"
- macro, then the results of the evaluation can be cached on the basis
- of <domain> and <ip> alone for as long as the shortest Time To Live
- (TTL) of all the DNS records involved.
-
-8.2. Expansion Examples
-
- The <sender> is strong-bad@email.example.com.
- The IPv4 SMTP client IP is 192.0.2.3.
- The IPv6 SMTP client IP is 2001:DB8::CB01.
- The PTR domain name of the client IP is mx.example.org.
-
- macro expansion
- ------- ----------------------------
- %{s} strong-bad@email.example.com
- %{o} email.example.com
- %{d} email.example.com
- %{d4} email.example.com
- %{d3} email.example.com
- %{d2} example.com
- %{d1} com
- %{dr} com.example.email
- %{d2r} example.email
- %{l} strong-bad
- %{l-} strong.bad
- %{lr} strong-bad
- %{lr-} bad.strong
- %{l1r-} strong
-
-
-
-
-
-
-
-
-
-
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-
-
- macro-string expansion
- --------------------------------------------------------------------
- %{ir}.%{v}._spf.%{d2} 3.2.0.192.in-addr._spf.example.com
- %{lr-}.lp._spf.%{d2} bad.strong.lp._spf.example.com
-
- %{lr-}.lp.%{ir}.%{v}._spf.%{d2}
- bad.strong.lp.3.2.0.192.in-addr._spf.example.com
-
- %{ir}.%{v}.%{l1r-}.lp._spf.%{d2}
- 3.2.0.192.in-addr.strong.lp._spf.example.com
-
- %{d2}.trusted-domains.example.net
- example.com.trusted-domains.example.net
-
- IPv6:
- %{ir}.%{v}._spf.%{d2} 1.0.B.C.0.0.0.0.
- 0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.8.B.D.0.1.0.0.2.ip6._spf.example.com
-
-9. Implications
-
- This section outlines the major implications that adoption of this
- document will have on various entities involved in Internet E-Mail.
- It is intended to make clear to the reader where this document
- knowingly affects the operation of such entities. This section is
- not a "how-to" manual, or a "best practices" document, and it is not
- a comprehensive list of what such entities should do in light of this
- document.
-
- This section is non-normative.
-
-9.1. Sending Domains
-
- Domains that wish to be compliant with this specification will need
- to determine the list of hosts that they allow to use their domain
- name in the "HELO" and "MAIL FROM" identities. It is recognized that
- forming such a list is not just a simple technical exercise, but
- involves policy decisions with both technical and administrative
- considerations.
-
- It can be helpful to publish records that include a "tracking
- exists:" mechanism. By looking at the name server logs, a rough list
- may then be generated. For example:
-
- v=spf1 exists:_h.%{h}._l.%{l}._o.%{o}._i.%{i}._spf.%{d} ?all
-
-
-
-
-
-
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-
-
-9.2. Mailing Lists
-
- Mailing lists must be aware of how they re-inject mail that is sent
- to the list. Mailing lists MUST comply with the requirements in
- [RFC2821], Section 3.10, and [RFC1123], Section 5.3.6, that say that
- the reverse-path MUST be changed to be the mailbox of a person or
- other entity who administers the list. Whereas the reasons for
- changing the reverse-path are many and long-standing, SPF adds
- enforcement to this requirement.
-
- In practice, almost all mailing list software in use already complies
- with this requirement. Mailing lists that do not comply may or may
- not encounter problems depending on how access to the list is
- restricted. Such lists that are entirely internal to a domain (only
- people in the domain can send to or receive from the list) are not
- affected.
-
-9.3. Forwarding Services and Aliases
-
- Forwarding services take mail that is received at a mailbox and
- direct it to some external mailbox. At the time of this writing, the
- near-universal practice of such services is to use the original "MAIL
- FROM" of a message when re-injecting it for delivery to the external
- mailbox. [RFC1123] and [RFC2821] describe this action as an "alias"
- rather than a "mail list". This means that the external mailbox's
- MTA sees all such mail in a connection from a host of the forwarding
- service, and so the "MAIL FROM" identity will not, in general, pass
- authorization.
-
- There are three places that techniques can be used to ameliorate this
- problem.
-
- 1. The beginning, when E-Mail is first sent.
-
- 1. "Neutral" results could be given for IP addresses that may be
- forwarders, instead of "Fail" results. For example:
-
- "v=spf1 mx -exists:%{ir}.sbl.spamhaus.example.org ?all"
-
- This would cause a lookup on an anti-spam DNS blacklist
- (DNSBL) and cause a result of "Fail" only for E-Mail coming
- from listed sources. All other E-Mail, including E-Mail sent
- through forwarders, would receive a "Neutral" result. By
- checking the DNSBL after the known good sources, problems with
- incorrect listing on the DNSBL are greatly reduced.
-
-
-
-
-
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-
- 2. The "MAIL FROM" identity could have additional information in
- the localpart that cryptographically identifies the mail as
- coming from an authorized source. In this case, such an SPF
- record could be used:
-
- "v=spf1 mx exists:%{l}._spf_verify.%{d} -all"
-
- Then, a specialized DNS server can be set up to serve the
- _spf_verify subdomain that validates the localpart. Although
- this requires an extra DNS lookup, this happens only when the
- E-Mail would otherwise be rejected as not coming from a known
- good source.
-
- Note that due to the 63-character limit for domain labels,
- this approach only works reliably if the localpart signature
- scheme is guaranteed either to only produce localparts with a
- maximum of 63 characters or to gracefully handle truncated
- localparts.
-
- 3. Similarly, a specialized DNS server could be set up that will
- rate-limit the E-Mail coming from unexpected IP addresses.
-
- "v=spf1 mx exists:%{ir}._spf_rate.%{d} -all"
-
- 4. SPF allows the creation of per-user policies for special
- cases. For example, the following SPF record and appropriate
- wildcard DNS records can be used:
-
- "v=spf1 mx redirect=%{l1r+}._at_.%{o}._spf.%{d}"
-
- 2. The middle, when E-Mail is forwarded.
-
- 1. Forwarding services can solve the problem by rewriting the
- "MAIL FROM" to be in their own domain. This means that mail
- bounced from the external mailbox will have to be re-bounced
- by the forwarding service. Various schemes to do this exist
- though they vary widely in complexity and resource
- requirements on the part of the forwarding service.
-
- 2. Several popular MTAs can be forced from "alias" semantics to
- "mailing list" semantics by configuring an additional alias
- with "owner-" prepended to the original alias name (e.g., an
- alias of "friends: george@example.com, fred@example.org" would
- need another alias of the form "owner-friends: localowner").
-
-
-
-
-
-
-
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-
-
- 3. The end, when E-Mail is received.
-
- 1. If the owner of the external mailbox wishes to trust the
- forwarding service, he can direct the external mailbox's MTA
- to skip SPF tests when the client host belongs to the
- forwarding service.
-
- 2. Tests against other identities, such as the "HELO" identity,
- may be used to override a failed test against the "MAIL FROM"
- identity.
-
- 3. For larger domains, it may not be possible to have a complete
- or accurate list of forwarding services used by the owners of
- the domain's mailboxes. In such cases, whitelists of
- generally-recognized forwarding services could be employed.
-
-9.4. Mail Services
-
- Service providers that offer mail services to third-party domains,
- such as sending of bulk mail, may want to adjust their setup in light
- of the authorization check described in this document. If the "MAIL
- FROM" identity used for such E-Mail uses the domain of the service
- provider, then the provider needs only to ensure that its sending
- host is authorized by its own SPF record, if any.
-
- If the "MAIL FROM" identity does not use the mail service provider's
- domain, then extra care must be taken. The SPF record format has
- several options for the third-party domain to authorize the service
- provider's MTAs to send mail on its behalf. For mail service
- providers, such as ISPs, that have a wide variety of customers using
- the same MTA, steps should be taken to prevent cross-customer forgery
- (see Section 10.4).
-
-9.5. MTA Relays
-
- The authorization check generally precludes the use of arbitrary MTA
- relays between sender and receiver of an E-Mail message.
-
- Within an organization, MTA relays can be effectively deployed.
- However, for purposes of this document, such relays are effectively
- transparent. The SPF authorization check is a check between border
- MTAs of different domains.
-
- For mail senders, this means that published SPF records must
- authorize any MTAs that actually send across the Internet. Usually,
- these are just the border MTAs as internal MTAs simply forward mail
- to these MTAs for delivery.
-
-
-
-
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-
-
- Mail receivers will generally want to perform the authorization check
- at the border MTAs, specifically including all secondary MXs. This
- allows mail that fails to be rejected during the SMTP session rather
- than bounced. Internal MTAs then do not perform the authorization
- test. To perform the authorization test other than at the border,
- the host that first transferred the message to the organization must
- be determined, which can be difficult to extract from the message
- header. Testing other than at the border is not recommended.
-
-10. Security Considerations
-
-10.1. Processing Limits
-
- As with most aspects of E-Mail, there are a number of ways that
- malicious parties could use the protocol as an avenue for a
- Denial-of-Service (DoS) attack. The processing limits outlined here
- are designed to prevent attacks such as the following:
-
- o A malicious party could create an SPF record with many references
- to a victim's domain and send many E-Mails to different SPF
- clients; those SPF clients would then create a DoS attack. In
- effect, the SPF clients are being used to amplify the attacker's
- bandwidth by using fewer bytes in the SMTP session than are used
- by the DNS queries. Using SPF clients also allows the attacker to
- hide the true source of the attack.
-
- o Whereas implementations of check_host() are supposed to limit the
- number of DNS lookups, malicious domains could publish records
- that exceed these limits in an attempt to waste computation effort
- at their targets when they send them mail. Malicious domains
- could also design SPF records that cause particular
- implementations to use excessive memory or CPU usage, or to
- trigger bugs.
-
- o Malicious parties could send a large volume of mail purporting to
- come from the intended target to a wide variety of legitimate mail
- hosts. These legitimate machines would then present a DNS load on
- the target as they fetched the relevant records.
-
- Of these, the case of a third party referenced in the SPF record is
- the easiest for a DoS attack to effectively exploit. As a result,
- limits that may seem reasonable for an individual mail server can
- still allow an unreasonable amount of bandwidth amplification.
- Therefore, the processing limits need to be quite low.
-
- SPF implementations MUST limit the number of mechanisms and modifiers
- that do DNS lookups to at most 10 per SPF check, including any
- lookups caused by the use of the "include" mechanism or the
-
-
-
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-
-
- "redirect" modifier. If this number is exceeded during a check, a
- PermError MUST be returned. The "include", "a", "mx", "ptr", and
- "exists" mechanisms as well as the "redirect" modifier do count
- against this limit. The "all", "ip4", and "ip6" mechanisms do not
- require DNS lookups and therefore do not count against this limit.
- The "exp" modifier does not count against this limit because the DNS
- lookup to fetch the explanation string occurs after the SPF record
- has been evaluated.
-
- When evaluating the "mx" and "ptr" mechanisms, or the %{p} macro,
- there MUST be a limit of no more than 10 MX or PTR RRs looked up and
- checked.
-
- SPF implementations SHOULD limit the total amount of data obtained
- from the DNS queries. For example, when DNS over TCP or EDNS0 are
- available, there may need to be an explicit limit to how much data
- will be accepted to prevent excessive bandwidth usage or memory usage
- and DoS attacks.
-
- MTAs or other processors MAY also impose a limit on the maximum
- amount of elapsed time to evaluate check_host(). Such a limit SHOULD
- allow at least 20 seconds. If such a limit is exceeded, the result
- of authorization SHOULD be "TempError".
-
- Domains publishing records SHOULD try to keep the number of "include"
- mechanisms and chained "redirect" modifiers to a minimum. Domains
- SHOULD also try to minimize the amount of other DNS information
- needed to evaluate a record. This can be done by choosing directives
- that require less DNS information and placing lower-cost mechanisms
- earlier in the SPF record.
-
- For example, consider a domain set up as follows:
-
- example.com. IN MX 10 mx.example.com.
- mx.example.com. IN A 192.0.2.1
- a.example.com. IN TXT "v=spf1 mx:example.com -all"
- b.example.com. IN TXT "v=spf1 a:mx.example.com -all"
- c.example.com. IN TXT "v=spf1 ip4:192.0.2.1 -all"
-
- Evaluating check_host() for the domain "a.example.com" requires the
- MX records for "example.com", and then the A records for the listed
- hosts. Evaluating for "b.example.com" requires only the A records.
- Evaluating for "c.example.com" requires none.
-
- However, there may be administrative considerations: using "a" over
- "ip4" allows hosts to be renumbered easily. Using "mx" over "a"
- allows the set of mail hosts to be changed easily.
-
-
-
-
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-
-
-10.2. SPF-Authorized E-Mail May Contain Other False Identities
-
- The "MAIL FROM" and "HELO" identity authorizations must not be
- construed to provide more assurance than they do. It is entirely
- possible for a malicious sender to inject a message using his own
- domain in the identities used by SPF, to have that domain's SPF
- record authorize the sending host, and yet the message can easily
- list other identities in its header. Unless the user or the MUA
- takes care to note that the authorized identity does not match the
- other more commonly-presented identities (such as the From: header
- field), the user may be lulled into a false sense of security.
-
-10.3. Spoofed DNS and IP Data
-
- There are two aspects of this protocol that malicious parties could
- exploit to undermine the validity of the check_host() function:
-
- o The evaluation of check_host() relies heavily on DNS. A malicious
- attacker could attack the DNS infrastructure and cause
- check_host() to see spoofed DNS data, and then return incorrect
- results. This could include returning "Pass" for an <ip> value
- where the actual domain's record would evaluate to "Fail". See
- [RFC3833] for a description of DNS weaknesses.
-
- o The client IP address, <ip>, is assumed to be correct. A
- malicious attacker could spoof TCP sequence numbers to make mail
- appear to come from a permitted host for a domain that the
- attacker is impersonating.
-
-10.4. Cross-User Forgery
-
- By definition, SPF policies just map domain names to sets of
- authorized MTAs, not whole E-Mail addresses to sets of authorized
- users. Although the "l" macro (Section 8) provides a limited way to
- define individual sets of authorized MTAs for specific E-Mail
- addresses, it is generally impossible to verify, through SPF, the use
- of specific E-Mail addresses by individual users of the same MTA.
-
- It is up to mail services and their MTAs to directly prevent
- cross-user forgery: based on SMTP AUTH ([RFC2554]), users should be
- restricted to using only those E-Mail addresses that are actually
- under their control (see [RFC4409], Section 6.1). Another means to
- verify the identity of individual users is message cryptography such
- as PGP ([RFC2440]) or S/MIME ([RFC3851]).
-
-
-
-
-
-
-
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-
-
-10.5. Untrusted Information Sources
-
- SPF uses information supplied by third parties, such as the "HELO"
- domain name, the "MAIL FROM" address, and SPF records. This
- information is then passed to the receiver in the Received-SPF: trace
- fields and possibly returned to the client MTA in the form of an SMTP
- rejection message. This information must be checked for invalid
- characters and excessively long lines.
-
- When the authorization check fails, an explanation string may be
- included in the reject response. Both the sender and the rejecting
- receiver need to be aware that the explanation was determined by the
- publisher of the SPF record checked and, in general, not the
- receiver. The explanation may contain malicious URLs, or it may be
- offensive or misleading.
-
- This is probably less of a concern than it may initially seem since
- such messages are returned to the sender, and the explanation strings
- come from the sender policy published by the domain in the identity
- claimed by that very sender. As long as the DSN is not redirected to
- someone other than the actual sender, the only people who see
- malicious explanation strings are people whose messages claim to be
- from domains that publish such strings in their SPF records. In
- practice, DSNs can be misdirected, such as when an MTA accepts an
- E-Mail and then later generates a DSN to a forged address, or when an
- E-Mail forwarder does not direct the DSN back to the original sender.
-
-10.6. Privacy Exposure
-
- Checking SPF records causes DNS queries to be sent to the domain
- owner. These DNS queries, especially if they are caused by the
- "exists" mechanism, can contain information about who is sending
- E-Mail and likely to which MTA the E-Mail is being sent. This can
- introduce some privacy concerns, which may be more or less of an
- issue depending on local laws and the relationship between the domain
- owner and the person sending the E-Mail.
-
-11. Contributors and Acknowledgements
-
- This document is largely based on the work of Meng Weng Wong and Mark
- Lentczner. Although, as this section acknowledges, many people have
- contributed to this document, a very large portion of the writing and
- editing are due to Meng and Mark.
-
- This design owes a debt of parentage to [RMX] by Hadmut Danisch and
- to [DMP] by Gordon Fecyk. The idea of using a DNS record to check
- the legitimacy of an E-Mail address traces its ancestry further back
- through messages on the namedroppers mailing list by Paul Vixie
-
-
-
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-
-
- [Vixie] (based on suggestion by Jim Miller) and by David Green
- [Green].
-
- Philip Gladstone contributed the concept of macros to the
- specification, multiplying the expressiveness of the language and
- making per-user and per-IP lookups possible.
-
- The authors would also like to thank the literally hundreds of
- individuals who have participated in the development of this design.
- They are far too numerous to name, but they include the following:
-
- The folks on the spf-discuss mailing list.
- The folks on the SPAM-L mailing list.
- The folks on the IRTF ASRG mailing list.
- The folks on the IETF MARID mailing list.
- The folks on #perl.
-
-12. IANA Considerations
-
-12.1. The SPF DNS Record Type
-
- The IANA has assigned a new Resource Record Type and Qtype from the
- DNS Parameters Registry for the SPF RR type with code 99.
-
-12.2. The Received-SPF Mail Header Field
-
- Per [RFC3864], the "Received-SPF:" header field is added to the IANA
- Permanent Message Header Field Registry. The following is the
- registration template:
-
- Header field name: Received-SPF
- Applicable protocol: mail ([RFC2822])
- Status: Experimental
- Author/Change controller: IETF
- Specification document(s): RFC 4408
- Related information:
- Requesting SPF Council review of any proposed changes and
- additions to this field are recommended. For information about
- the SPF Council see http://www.openspf.org/Council
-
-13. References
-
-13.1. Normative References
-
- [RFC1035] Mockapetris, P., "Domain names - implementation and
- specification", STD 13, RFC 1035, November 1987.
-
-
-
-
-
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-
-
- [RFC1123] Braden, R., "Requirements for Internet Hosts - Application
- and Support", STD 3, RFC 1123, October 1989.
-
- [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
- Requirement Levels", BCP 14, RFC 2119, March 1997.
-
- [RFC2821] Klensin, J., "Simple Mail Transfer Protocol", RFC 2821,
- April 2001.
-
- [RFC2822] Resnick, P., "Internet Message Format", RFC 2822, April
- 2001.
-
- [RFC3464] Moore, K. and G. Vaudreuil, "An Extensible Message Format
- for Delivery Status Notifications", RFC 3464, January
- 2003.
-
- [RFC3513] Hinden, R. and S. Deering, "Internet Protocol Version 6
- (IPv6) Addressing Architecture", RFC 3513, April 2003.
-
- [RFC3864] Klyne, G., Nottingham, M., and J. Mogul, "Registration
- Procedures for Message Header Fields", BCP 90, RFC 3864,
- September 2004.
-
- [RFC3986] Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform
- Resource Identifier (URI): Generic Syntax", STD 66, RFC
- 3986, January 2005.
-
- [RFC4234] Crocker, D. and P. Overell, "Augmented BNF for Syntax
- Specifications: ABNF", RFC 4234, October 2005.
-
- [US-ASCII] American National Standards Institute (formerly United
- States of America Standards Institute), "USA Code for
- Information Interchange, X3.4", 1968.
-
- ANSI X3.4-1968 has been replaced by newer versions with slight
- modifications, but the 1968 version remains definitive for
- the Internet.
-
-13.2 Informative References
-
- [RFC1034] Mockapetris, P., "Domain names - concepts and facilities",
- STD 13, RFC 1034, November 1987.
-
- [RFC1983] Malkin, G., "Internet Users' Glossary", RFC 1983, August
- 1996.
-
- [RFC2440] Callas, J., Donnerhacke, L., Finney, H., and R. Thayer,
- "OpenPGP Message Format", RFC 2440, November 1998.
-
-
-
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-
-
- [RFC2554] Myers, J., "SMTP Service Extension for Authentication",
- RFC 2554, March 1999.
-
- [RFC3696] Klensin, J., "Application Techniques for Checking and
- Transformation of Names", RFC 3696, February 2004.
-
- [RFC3833] Atkins, D. and R. Austein, "Threat Analysis of the Domain
- Name System (DNS)", RFC 3833, August 2004.
-
- [RFC3851] Ramsdell, B., "Secure/Multipurpose Internet Mail
- Extensions (S/MIME) Version 3.1 Message Specification",
- RFC 3851, July 2004.
-
- [RFC4409] Gellens, R. and J. Klensin, "Message Submission for Mail",
- RFC 4409, April 2006.
-
- [RMX] Danish, H., "The RMX DNS RR Type for light weight sender
- authentication", Work In Progress
-
- [DMP] Fecyk, G., "Designated Mailers Protocol", Work In Progress
-
- [Vixie] Vixie, P., "Repudiating MAIL FROM", 2002.
-
- [Green] Green, D., "Domain-Authorized SMTP Mail", 2002.
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
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-
-
-Appendix A. Collected ABNF
-
- This section is normative and any discrepancies with the ABNF
- fragments in the preceding text are to be resolved in favor of this
- grammar.
-
- See [RFC4234] for ABNF notation. Please note that as per this ABNF
- definition, literal text strings (those in quotes) are case-
- insensitive. Hence, "mx" matches "mx", "MX", "mX", and "Mx".
-
- record = version terms *SP
- version = "v=spf1"
-
- terms = *( 1*SP ( directive / modifier ) )
-
- directive = [ qualifier ] mechanism
- qualifier = "+" / "-" / "?" / "~"
- mechanism = ( all / include
- / A / MX / PTR / IP4 / IP6 / exists )
-
- all = "all"
- include = "include" ":" domain-spec
- A = "a" [ ":" domain-spec ] [ dual-cidr-length ]
- MX = "mx" [ ":" domain-spec ] [ dual-cidr-length ]
- PTR = "ptr" [ ":" domain-spec ]
- IP4 = "ip4" ":" ip4-network [ ip4-cidr-length ]
- IP6 = "ip6" ":" ip6-network [ ip6-cidr-length ]
- exists = "exists" ":" domain-spec
-
- modifier = redirect / explanation / unknown-modifier
- redirect = "redirect" "=" domain-spec
- explanation = "exp" "=" domain-spec
- unknown-modifier = name "=" macro-string
-
- ip4-cidr-length = "/" 1*DIGIT
- ip6-cidr-length = "/" 1*DIGIT
- dual-cidr-length = [ ip4-cidr-length ] [ "/" ip6-cidr-length ]
-
- ip4-network = qnum "." qnum "." qnum "." qnum
- qnum = DIGIT ; 0-9
- / %x31-39 DIGIT ; 10-99
- / "1" 2DIGIT ; 100-199
- / "2" %x30-34 DIGIT ; 200-249
- / "25" %x30-35 ; 250-255
- ; conventional dotted quad notation. e.g., 192.0.2.0
- ip6-network = <as per [RFC 3513], section 2.2>
- ; e.g., 2001:DB8::CD30
-
-
-
-
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-RFC 4408 Sender Policy Framework (SPF) April 2006
-
-
- domain-spec = macro-string domain-end
- domain-end = ( "." toplabel [ "." ] ) / macro-expand
- toplabel = ( *alphanum ALPHA *alphanum ) /
- ( 1*alphanum "-" *( alphanum / "-" ) alphanum )
- ; LDH rule plus additional TLD restrictions
- ; (see [RFC3696], Section 2)
-
- alphanum = ALPHA / DIGIT
-
- explain-string = *( macro-string / SP )
-
- macro-string = *( macro-expand / macro-literal )
- macro-expand = ( "%{" macro-letter transformers *delimiter "}" )
- / "%%" / "%_" / "%-"
- macro-literal = %x21-24 / %x26-7E
- ; visible characters except "%"
- macro-letter = "s" / "l" / "o" / "d" / "i" / "p" / "h" /
- "c" / "r" / "t"
- transformers = *DIGIT [ "r" ]
- delimiter = "." / "-" / "+" / "," / "/" / "_" / "="
-
- name = ALPHA *( ALPHA / DIGIT / "-" / "_" / "." )
-
- header-field = "Received-SPF:" [CFWS] result FWS [comment FWS]
- [ key-value-list ] CRLF
-
- result = "Pass" / "Fail" / "SoftFail" / "Neutral" /
- "None" / "TempError" / "PermError"
-
- key-value-list = key-value-pair *( ";" [CFWS] key-value-pair )
- [";"]
-
- key-value-pair = key [CFWS] "=" ( dot-atom / quoted-string )
-
- key = "client-ip" / "envelope-from" / "helo" /
- "problem" / "receiver" / "identity" /
- mechanism / "x-" name / name
-
- identity = "mailfrom" ; for the "MAIL FROM" identity
- / "helo" ; for the "HELO" identity
- / name ; other identities
-
- dot-atom = <unquoted word as per [RFC2822]>
- quoted-string = <quoted string as per [RFC2822]>
- comment = <comment string as per [RFC2822]>
- CFWS = <comment or folding white space as per [RFC2822]>
- FWS = <folding white space as per [RFC2822]>
- CRLF = <standard end-of-line token as per [RFC2822]>
-
-
-
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-
-
-Appendix B. Extended Examples
-
- These examples are based on the following DNS setup:
-
- ; A domain with two mail servers, two hosts
- ; and two servers at the domain name
- $ORIGIN example.com.
- @ MX 10 mail-a
- MX 20 mail-b
- A 192.0.2.10
- A 192.0.2.11
- amy A 192.0.2.65
- bob A 192.0.2.66
- mail-a A 192.0.2.129
- mail-b A 192.0.2.130
- www CNAME example.com.
-
- ; A related domain
- $ORIGIN example.org.
- @ MX 10 mail-c
- mail-c A 192.0.2.140
-
- ; The reverse IP for those addresses
- $ORIGIN 2.0.192.in-addr.arpa.
- 10 PTR example.com.
- 11 PTR example.com.
- 65 PTR amy.example.com.
- 66 PTR bob.example.com.
- 129 PTR mail-a.example.com.
- 130 PTR mail-b.example.com.
- 140 PTR mail-c.example.org.
-
- ; A rogue reverse IP domain that claims to be
- ; something it's not
- $ORIGIN 0.0.10.in-addr.arpa.
- 4 PTR bob.example.com.
-
-B.1. Simple Examples
-
- These examples show various possible published records for
- example.com and which values if <ip> would cause check_host() to
- return "Pass". Note that <domain> is "example.com".
-
- v=spf1 +all
- -- any <ip> passes
-
- v=spf1 a -all
- -- hosts 192.0.2.10 and 192.0.2.11 pass
-
-
-
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-RFC 4408 Sender Policy Framework (SPF) April 2006
-
-
- v=spf1 a:example.org -all
- -- no sending hosts pass since example.org has no A records
-
- v=spf1 mx -all
- -- sending hosts 192.0.2.129 and 192.0.2.130 pass
-
- v=spf1 mx:example.org -all
- -- sending host 192.0.2.140 passes
-
- v=spf1 mx mx:example.org -all
- -- sending hosts 192.0.2.129, 192.0.2.130, and 192.0.2.140 pass
-
- v=spf1 mx/30 mx:example.org/30 -all
- -- any sending host in 192.0.2.128/30 or 192.0.2.140/30 passes
-
- v=spf1 ptr -all
- -- sending host 192.0.2.65 passes (reverse DNS is valid and is in
- example.com)
- -- sending host 192.0.2.140 fails (reverse DNS is valid, but not
- in example.com)
- -- sending host 10.0.0.4 fails (reverse IP is not valid)
-
- v=spf1 ip4:192.0.2.128/28 -all
- -- sending host 192.0.2.65 fails
- -- sending host 192.0.2.129 passes
-
-B.2. Multiple Domain Example
-
- These examples show the effect of related records:
-
- example.org: "v=spf1 include:example.com include:example.net -all"
-
- This record would be used if mail from example.org actually came
- through servers at example.com and example.net. Example.org's
- designated servers are the union of example.com's and example.net's
- designated servers.
-
- la.example.org: "v=spf1 redirect=example.org"
- ny.example.org: "v=spf1 redirect=example.org"
- sf.example.org: "v=spf1 redirect=example.org"
-
- These records allow a set of domains that all use the same mail
- system to make use of that mail system's record. In this way, only
- the mail system's record needs to be updated when the mail setup
- changes. These domains' records never have to change.
-
-
-
-
-
-
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-RFC 4408 Sender Policy Framework (SPF) April 2006
-
-
-B.3. DNSBL Style Example
-
- Imagine that, in addition to the domain records listed above, there
- are these:
-
- $ORIGIN _spf.example.com. mary.mobile-users A
- 127.0.0.2 fred.mobile-users A 127.0.0.2
- 15.15.168.192.joel.remote-users A 127.0.0.2
- 16.15.168.192.joel.remote-users A 127.0.0.2
-
- The following records describe users at example.com who mail from
- arbitrary servers, or who mail from personal servers.
-
- example.com:
-
- v=spf1 mx
- include:mobile-users._spf.%{d}
- include:remote-users._spf.%{d}
- -all
-
- mobile-users._spf.example.com:
-
- v=spf1 exists:%{l1r+}.%{d}
-
- remote-users._spf.example.com:
-
- v=spf1 exists:%{ir}.%{l1r+}.%{d}
-
-B.4. Multiple Requirements Example
-
- Say that your sender policy requires both that the IP address is
- within a certain range and that the reverse DNS for the IP matches.
- This can be done several ways, including the following:
-
- example.com. SPF ( "v=spf1 "
- "-include:ip4._spf.%{d} "
- "-include:ptr._spf.%{d} "
- "+all" )
- ip4._spf.example.com. SPF "v=spf1 -ip4:192.0.2.0/24 +all"
- ptr._spf.example.com. SPF "v=spf1 -ptr +all"
-
- This example shows how the "-include" mechanism can be useful, how an
- SPF record that ends in "+all" can be very restrictive, and the use
- of De Morgan's Law.
-
-
-
-
-
-
-
-Wong & Schlitt Experimental [Page 46]
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-RFC 4408 Sender Policy Framework (SPF) April 2006
-
-
-Authors' Addresses
-
- Meng Weng Wong
- Singapore
-
- EMail: mengwong+spf@pobox.com
-
-
- Wayne Schlitt
- 4615 Meredeth #9
- Lincoln Nebraska, NE 68506
- United States of America
-
- EMail: wayne@schlitt.net
- URI: http://www.schlitt.net/spf/
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-Wong & Schlitt Experimental [Page 47]
-\f
-RFC 4408 Sender Policy Framework (SPF) April 2006
-
-
-Full Copyright Statement
-
- Copyright (C) The Internet Society (2006).
-
- This document is subject to the rights, licenses and restrictions
- contained in BCP 78, and except as set forth therein, the authors
- retain all their rights.
-
- This document and the information contained herein are provided on an
- "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS
- OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND THE INTERNET
- ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED,
- INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE
- INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED
- WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
-
-Intellectual Property
-
- The IETF takes no position regarding the validity or scope of any
- Intellectual Property Rights or other rights that might be claimed to
- pertain to the implementation or use of the technology described in
- this document or the extent to which any license under such rights
- might or might not be available; nor does it represent that it has
- made any independent effort to identify any such rights. Information
- on the procedures with respect to rights in RFC documents can be
- found in BCP 78 and BCP 79.
-
- Copies of IPR disclosures made to the IETF Secretariat and any
- assurances of licenses to be made available, or the result of an
- attempt made to obtain a general license or permission for the use of
- such proprietary rights by implementers or users of this
- specification can be obtained from the IETF on-line IPR repository at
- http://www.ietf.org/ipr.
-
- The IETF invites any interested party to bring to its attention any
- copyrights, patents or patent applications, or other proprietary
- rights that may cover technology that may be required to implement
- this standard. Please address the information to the IETF at
- ietf-ipr@ietf.org.
-
-Acknowledgement
-
- Funding for the RFC Editor function is provided by the IETF
- Administrative Support Activity (IASA).
-
-
-
-
-
-
-
-Wong & Schlitt Experimental [Page 48]
-\f
+++ /dev/null
-
-
-
-
-
-
-Network Working Group S. Weiler
-Request for Comments: 4470 SPARTA, Inc.
-Updates: 4035, 4034 J. Ihren
-Category: Standards Track Autonomica AB
- April 2006
-
-
- Minimally Covering NSEC Records and DNSSEC On-line Signing
-
-
-Status of This Memo
-
- This document specifies an Internet standards track protocol for the
- Internet community, and requests discussion and suggestions for
- improvements. Please refer to the current edition of the "Internet
- Official Protocol Standards" (STD 1) for the standardization state
- and status of this protocol. Distribution of this memo is unlimited.
-
-Copyright Notice
-
- Copyright (C) The Internet Society (2006).
-
-Abstract
-
- This document describes how to construct DNSSEC NSEC resource records
- that cover a smaller range of names than called for by RFC 4034. By
- generating and signing these records on demand, authoritative name
- servers can effectively stop the disclosure of zone contents
- otherwise made possible by walking the chain of NSEC records in a
- signed zone.
-
-Table of Contents
-
- 1. Introduction ....................................................1
- 2. Applicability of This Technique .................................2
- 3. Minimally Covering NSEC Records .................................2
- 4. Better Epsilon Functions ........................................4
- 5. Security Considerations .........................................5
- 6. Acknowledgements ................................................6
- 7. Normative References ............................................6
-
-1. Introduction
-
- With DNSSEC [1], an NSEC record lists the next instantiated name in
- its zone, proving that no names exist in the "span" between the
- NSEC's owner name and the name in the "next name" field. In this
- document, an NSEC record is said to "cover" the names between its
- owner name and next name.
-
-
-
-Weiler & Ihren Standards Track [Page 1]
-\f
-RFC 4470 NSEC Epsilon April 2006
-
-
- Through repeated queries that return NSEC records, it is possible to
- retrieve all of the names in the zone, a process commonly called
- "walking" the zone. Some zone owners have policies forbidding zone
- transfers by arbitrary clients; this side effect of the NSEC
- architecture subverts those policies.
-
- This document presents a way to prevent zone walking by constructing
- NSEC records that cover fewer names. These records can make zone
- walking take approximately as many queries as simply asking for all
- possible names in a zone, making zone walking impractical. Some of
- these records must be created and signed on demand, which requires
- on-line private keys. Anyone contemplating use of this technique is
- strongly encouraged to review the discussion of the risks of on-line
- signing in Section 5.
-
-1.2. Keywords
-
- The keywords "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
- "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
- document are to be interpreted as described in RFC 2119 [4].
-
-2. Applicability of This Technique
-
- The technique presented here may be useful to a zone owner that wants
- to use DNSSEC, is concerned about exposure of its zone contents via
- zone walking, and is willing to bear the costs of on-line signing.
-
- As discussed in Section 5, on-line signing has several security
- risks, including an increased likelihood of private keys being
- disclosed and an increased risk of denial of service attack. Anyone
- contemplating use of this technique is strongly encouraged to review
- the discussion of the risks of on-line signing in Section 5.
-
- Furthermore, at the time this document was published, the DNSEXT
- working group was actively working on a mechanism to prevent zone
- walking that does not require on-line signing (tentatively called
- NSEC3). The new mechanism is likely to expose slightly more
- information about the zone than this technique (e.g., the number of
- instantiated names), but it may be preferable to this technique.
-
-3. Minimally Covering NSEC Records
-
- This mechanism involves changes to NSEC records for instantiated
- names, which can still be generated and signed in advance, as well as
- the on-demand generation and signing of new NSEC records whenever a
- name must be proven not to exist.
-
-
-
-
-
-Weiler & Ihren Standards Track [Page 2]
-\f
-RFC 4470 NSEC Epsilon April 2006
-
-
- In the "next name" field of instantiated names' NSEC records, rather
- than list the next instantiated name in the zone, list any name that
- falls lexically after the NSEC's owner name and before the next
- instantiated name in the zone, according to the ordering function in
- RFC 4034 [2] Section 6.1. This relaxes the requirement in Section
- 4.1.1 of RFC 4034 that the "next name" field contains the next owner
- name in the zone. This change is expected to be fully compatible
- with all existing DNSSEC validators. These NSEC records are returned
- whenever proving something specifically about the owner name (e.g.,
- that no resource records of a given type appear at that name).
-
- Whenever an NSEC record is needed to prove the non-existence of a
- name, a new NSEC record is dynamically produced and signed. The new
- NSEC record has an owner name lexically before the QNAME but
- lexically following any existing name and a "next name" lexically
- following the QNAME but before any existing name.
-
- The generated NSEC record's type bitmap MUST have the RRSIG and NSEC
- bits set and SHOULD NOT have any other bits set. This relaxes the
- requirement in Section 2.3 of RFC4035 that NSEC RRs not appear at
- names that did not exist before the zone was signed.
-
- The functions to generate the lexically following and proceeding
- names need not be perfect or consistent, but the generated NSEC
- records must not cover any existing names. Furthermore, this
- technique works best when the generated NSEC records cover as few
- names as possible. In this document, the functions that generate the
- nearby names are called "epsilon" functions, a reference to the
- mathematical convention of using the greek letter epsilon to
- represent small deviations.
-
- An NSEC record denying the existence of a wildcard may be generated
- in the same way. Since the NSEC record covering a non-existent
- wildcard is likely to be used in response to many queries,
- authoritative name servers using the techniques described here may
- want to pregenerate or cache that record and its corresponding RRSIG.
-
- For example, a query for an A record at the non-instantiated name
- example.com might produce the following two NSEC records, the first
- denying the existence of the name example.com and the second denying
- the existence of a wildcard:
-
- exampld.com 3600 IN NSEC example-.com ( RRSIG NSEC )
-
- \).com 3600 IN NSEC +.com ( RRSIG NSEC )
-
-
-
-
-
-
-Weiler & Ihren Standards Track [Page 3]
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-RFC 4470 NSEC Epsilon April 2006
-
-
- Before answering a query with these records, an authoritative server
- must test for the existence of names between these endpoints. If the
- generated NSEC would cover existing names (e.g., exampldd.com or
- *bizarre.example.com), a better epsilon function may be used or the
- covered name closest to the QNAME could be used as the NSEC owner
- name or next name, as appropriate. If an existing name is used as
- the NSEC owner name, that name's real NSEC record MUST be returned.
- Using the same example, assuming an exampldd.com delegation exists,
- this record might be returned from the parent:
-
- exampldd.com 3600 IN NSEC example-.com ( NS DS RRSIG NSEC )
-
- Like every authoritative record in the zone, each generated NSEC
- record MUST have corresponding RRSIGs generated using each algorithm
- (but not necessarily each DNSKEY) in the zone's DNSKEY RRset, as
- described in RFC 4035 [3] Section 2.2. To minimize the number of
- signatures that must be generated, a zone may wish to limit the
- number of algorithms in its DNSKEY RRset.
-
-4. Better Epsilon Functions
-
- Section 6.1 of RFC 4034 defines a strict ordering of DNS names.
- Working backward from that definition, it should be possible to
- define epsilon functions that generate the immediately following and
- preceding names, respectively. This document does not define such
- functions. Instead, this section presents functions that come
- reasonably close to the perfect ones. As described above, an
- authoritative server should still ensure than no generated NSEC
- covers any existing name.
-
- To increment a name, add a leading label with a single null (zero-
- value) octet.
-
- To decrement a name, decrement the last character of the leftmost
- label, then fill that label to a length of 63 octets with octets of
- value 255. To decrement a null (zero-value) octet, remove the octet
- -- if an empty label is left, remove the label. Defining this
- function numerically: fill the leftmost label to its maximum length
- with zeros (numeric, not ASCII zeros) and subtract one.
-
- In response to a query for the non-existent name foo.example.com,
- these functions produce NSEC records of the following:
-
-
-
-
-
-
-
-
-
-Weiler & Ihren Standards Track [Page 4]
-\f
-RFC 4470 NSEC Epsilon April 2006
-
-
- fon\255\255\255\255\255\255\255\255\255\255\255\255\255\255
- \255\255\255\255\255\255\255\255\255\255\255\255\255\255\255
- \255\255\255\255\255\255\255\255\255\255\255\255\255\255\255
- \255\255\255\255\255\255\255\255\255\255\255\255\255\255\255
- \255.example.com 3600 IN NSEC \000.foo.example.com ( NSEC RRSIG )
-
- \)\255\255\255\255\255\255\255\255\255\255\255\255\255\255\255
- \255\255\255\255\255\255\255\255\255\255\255\255\255\255\255
- \255\255\255\255\255\255\255\255\255\255\255\255\255\255\255
- \255\255\255\255\255\255\255\255\255\255\255\255\255\255\255
- \255\255.example.com 3600 IN NSEC \000.*.example.com ( NSEC RRSIG )
-
- The first of these NSEC RRs proves that no exact match for
- foo.example.com exists, and the second proves that there is no
- wildcard in example.com.
-
- Both of these functions are imperfect: they do not take into account
- constraints on number of labels in a name nor total length of a name.
- As noted in the previous section, though, this technique does not
- depend on the use of perfect epsilon functions: it is sufficient to
- test whether any instantiated names fall into the span covered by the
- generated NSEC and, if so, substitute those instantiated owner names
- for the NSEC owner name or next name, as appropriate.
-
-5. Security Considerations
-
- This approach requires on-demand generation of RRSIG records. This
- creates several new vulnerabilities.
-
- First, on-demand signing requires that a zone's authoritative servers
- have access to its private keys. Storing private keys on well-known
- Internet-accessible servers may make them more vulnerable to
- unintended disclosure.
-
- Second, since generation of digital signatures tends to be
- computationally demanding, the requirement for on-demand signing
- makes authoritative servers vulnerable to a denial of service attack.
-
- Last, if the epsilon functions are predictable, on-demand signing may
- enable a chosen-plaintext attack on a zone's private keys. Zones
- using this approach should attempt to use cryptographic algorithms
- that are resistant to chosen-plaintext attacks. It is worth noting
- that although DNSSEC has a "mandatory to implement" algorithm, that
- is a requirement on resolvers and validators -- there is no
- requirement that a zone be signed with any given algorithm.
-
- The success of using minimally covering NSEC records to prevent zone
- walking depends greatly on the quality of the epsilon functions
-
-
-
-Weiler & Ihren Standards Track [Page 5]
-\f
-RFC 4470 NSEC Epsilon April 2006
-
-
- chosen. An increment function that chooses a name obviously derived
- from the next instantiated name may be easily reverse engineered,
- destroying the value of this technique. An increment function that
- always returns a name close to the next instantiated name is likewise
- a poor choice. Good choices of epsilon functions are the ones that
- produce the immediately following and preceding names, respectively,
- though zone administrators may wish to use less perfect functions
- that return more human-friendly names than the functions described in
- Section 4 above.
-
- Another obvious but misguided concern is the danger from synthesized
- NSEC records being replayed. It is possible for an attacker to
- replay an old but still validly signed NSEC record after a new name
- has been added in the span covered by that NSEC, incorrectly proving
- that there is no record at that name. This danger exists with DNSSEC
- as defined in [3]. The techniques described here actually decrease
- the danger, since the span covered by any NSEC record is smaller than
- before. Choosing better epsilon functions will further reduce this
- danger.
-
-6. Acknowledgements
-
- Many individuals contributed to this design. They include, in
- addition to the authors of this document, Olaf Kolkman, Ed Lewis,
- Peter Koch, Matt Larson, David Blacka, Suzanne Woolf, Jaap Akkerhuis,
- Jakob Schlyter, Bill Manning, and Joao Damas.
-
- In addition, the editors would like to thank Ed Lewis, Scott Rose,
- and David Blacka for their careful review of the document.
-
-7. Normative References
-
- [1] Arends, R., Austein, R., Larson, M., Massey, D., and S. Rose,
- "DNS Security Introduction and Requirements", RFC 4033, March
- 2005.
-
- [2] Arends, R., Austein, R., Larson, M., Massey, D., and S. Rose,
- "Resource Records for the DNS Security Extensions", RFC 4034,
- March 2005.
-
- [3] Arends, R., Austein, R., Larson, M., Massey, D., and S. Rose,
- "Protocol Modifications for the DNS Security Extensions", RFC
- 4035, March 2005.
-
- [4] Bradner, S., "Key words for use in RFCs to Indicate Requirement
- Levels", BCP 14, RFC 2119, March 1997.
-
-
-
-
-
-Weiler & Ihren Standards Track [Page 6]
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-RFC 4470 NSEC Epsilon April 2006
-
-
-Authors' Addresses
-
- Samuel Weiler
- SPARTA, Inc.
- 7075 Samuel Morse Drive
- Columbia, Maryland 21046
- US
-
- EMail: weiler@tislabs.com
-
-
- Johan Ihren
- Autonomica AB
- Bellmansgatan 30
- Stockholm SE-118 47
- Sweden
-
- EMail: johani@autonomica.se
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-Weiler & Ihren Standards Track [Page 7]
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-RFC 4470 NSEC Epsilon April 2006
-
-
-Full Copyright Statement
-
- Copyright (C) The Internet Society (2006).
-
- This document is subject to the rights, licenses and restrictions
- contained in BCP 78, and except as set forth therein, the authors
- retain all their rights.
-
- This document and the information contained herein are provided on an
- "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS
- OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND THE INTERNET
- ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED,
- INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE
- INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED
- WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
-
-Intellectual Property
-
- The IETF takes no position regarding the validity or scope of any
- Intellectual Property Rights or other rights that might be claimed to
- pertain to the implementation or use of the technology described in
- this document or the extent to which any license under such rights
- might or might not be available; nor does it represent that it has
- made any independent effort to identify any such rights. Information
- on the procedures with respect to rights in RFC documents can be
- found in BCP 78 and BCP 79.
-
- Copies of IPR disclosures made to the IETF Secretariat and any
- assurances of licenses to be made available, or the result of an
- attempt made to obtain a general license or permission for the use of
- such proprietary rights by implementers or users of this
- specification can be obtained from the IETF on-line IPR repository at
- http://www.ietf.org/ipr.
-
- The IETF invites any interested party to bring to its attention any
- copyrights, patents or patent applications, or other proprietary
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- this standard. Please address the information to the IETF at
- ietf-ipr@ietf.org.
-
-Acknowledgement
-
- Funding for the RFC Editor function is provided by the IETF
- Administrative Support Activity (IASA).
-
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+++ /dev/null
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-Network Working Group D. Eastlake 3rd
-Request for Comments: 4634 Motorola Labs
-Updates: 3174 T. Hansen
-Category: Informational AT&T Labs
- July 2006
-
-
- US Secure Hash Algorithms (SHA and HMAC-SHA)
-
-Status of This Memo
-
- This memo provides information for the Internet community. It does
- not specify an Internet standard of any kind. Distribution of this
- memo is unlimited.
-
-Copyright Notice
-
- Copyright (C) The Internet Society (2006).
-
-Abstract
-
- The United States of America has adopted a suite of Secure Hash
- Algorithms (SHAs), including four beyond SHA-1, as part of a Federal
- Information Processing Standard (FIPS), specifically SHA-224 (RFC
- 3874), SHA-256, SHA-384, and SHA-512. The purpose of this document
- is to make source code performing these hash functions conveniently
- available to the Internet community. The sample code supports input
- strings of arbitrary bit length. SHA-1's sample code from RFC 3174
- has also been updated to handle input strings of arbitrary bit
- length. Most of the text herein was adapted by the authors from FIPS
- 180-2.
-
- Code to perform SHA-based HMACs, with arbitrary bit length text, is
- also included.
-
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-Eastlake 3rd & Hansen Informational [Page 1]
-\f
-RFC 4634 SHAs and HMAC-SHAs July 2006
-
-
-Table of Contents
-
- 1. Overview of Contents ............................................3
- 1.1. License ....................................................4
- 2. Notation for Bit Strings and Integers ...........................4
- 3. Operations on Words .............................................5
- 4. Message Padding and Parsing .....................................6
- 4.1. SHA-224 and SHA-256 ........................................7
- 4.2. SHA-384 and SHA-512 ........................................8
- 5. Functions and Constants Used ....................................9
- 5.1. SHA-224 and SHA-256 ........................................9
- 5.2. SHA-384 and SHA-512 .......................................10
- 6. Computing the Message Digest ...................................11
- 6.1. SHA-224 and SHA-256 Initialization ........................11
- 6.2. SHA-224 and SHA-256 Processing ............................11
- 6.3. SHA-384 and SHA-512 Initialization ........................13
- 6.4. SHA-384 and SHA-512 Processing ............................14
- 7. SHA-Based HMACs ................................................15
- 8. C Code for SHAs ................................................15
- 8.1. The .h File ...............................................18
- 8.2. The SHA Code ..............................................24
- 8.2.1. sha1.c .............................................24
- 8.2.2. sha224-256.c .......................................33
- 8.2.3. sha384-512.c .......................................45
- 8.2.4. usha.c .............................................67
- 8.2.5. sha-private.h ......................................72
- 8.3. The HMAC Code .............................................73
- 8.4. The Test Driver ...........................................78
- 9. Security Considerations .......................................106
- 10. Normative References .........................................106
- 11. Informative References .......................................106
-
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-Eastlake 3rd & Hansen Informational [Page 2]
-\f
-RFC 4634 SHAs and HMAC-SHAs July 2006
-
-
-1. Overview of Contents
-
- NOTE: Much of the text below is taken from [FIPS180-2] and assertions
- therein of the security of the algorithms described are made by the
- US Government, the author of [FIPS180-2], and not by the authors of
- this document.
-
- The text below specifies Secure Hash Algorithms, SHA-224 [RFC3874],
- SHA-256, SHA-384, and SHA-512, for computing a condensed
- representation of a message or a data file. (SHA-1 is specified in
- [RFC3174].) When a message of any length < 2^64 bits (for SHA-224
- and SHA-256) or < 2^128 bits (for SHA-384 and SHA-512) is input to
- one of these algorithms, the result is an output called a message
- digest. The message digests range in length from 224 to 512 bits,
- depending on the algorithm. Secure hash algorithms are typically
- used with other cryptographic algorithms, such as digital signature
- algorithms and keyed hash authentication codes, or in the generation
- of random numbers [RFC4086].
-
- The four algorithms specified in this document are called secure
- because it is computationally infeasible to (1) find a message that
- corresponds to a given message digest, or (2) find two different
- messages that produce the same message digest. Any change to a
- message in transit will, with very high probability, result in a
- different message digest. This will result in a verification failure
- when the secure hash algorithm is used with a digital signature
- algorithm or a keyed-hash message authentication algorithm.
-
- The code provided herein supports input strings of arbitrary bit
- length. SHA-1's sample code from [RFC3174] has also been updated to
- handle input strings of arbitrary bit length. See Section 1.1 for
- license information for this code.
-
- Section 2 below defines the terminology and functions used as
- building blocks to form these algorithms. Section 3 describes the
- fundamental operations on words from which these algorithms are
- built. Section 4 describes how messages are padded up to an integral
- multiple of the required block size and then parsed into blocks.
- Section 5 defines the constants and the composite functions used to
- specify these algorithms. Section 6 gives the actual specification
- for the SHA-224, SHA-256, SHA-384, and SHA-512 functions. Section 7
- provides pointers to the specification of HMAC keyed message
- authentication codes based on the SHA algorithms. Section 8 gives
- sample code for the SHA algorithms and Section 9 code for SHA-based
- HMACs. The SHA-based HMACs will accept arbitrary bit length text.
-
-
-
-
-
-
-Eastlake 3rd & Hansen Informational [Page 3]
-\f
-RFC 4634 SHAs and HMAC-SHAs July 2006
-
-
-1.1. License
-
- Permission is granted for all uses, commercial and non-commercial, of
- the sample code found in Section 8. Royalty free license to use,
- copy, modify and distribute the software found in Section 8 is
- granted, provided that this document is identified in all material
- mentioning or referencing this software, and provided that
- redistributed derivative works do not contain misleading author or
- version information.
-
- The authors make no representations concerning either the
- merchantability of this software or the suitability of this software
- for any particular purpose. It is provided "as is" without express
- or implied warranty of any kind.
-
-2. Notation for Bit Strings and Integers
-
- The following terminology related to bit strings and integers will be
- used:
-
- a. A hex digit is an element of the set {0, 1, ... , 9, A, ... ,
- F}. A hex digit is the representation of a 4-bit string.
- Examples: 7 = 0111, A = 1010.
-
- b. A word equals a 32-bit or 64-bit string, which may be
- represented as a sequence of 8 or 16 hex digits, respectively.
- To convert a word to hex digits, each 4-bit string is converted
- to its hex equivalent as described in (a) above. Example:
-
- 1010 0001 0000 0011 1111 1110 0010 0011 = A103FE23.
-
- Throughout this document, the "big-endian" convention is used
- when expressing both 32-bit and 64-bit words, so that within
- each word the most significant bit is shown in the left-most bit
- position.
-
- c. An integer may be represented as a word or pair of words.
-
- An integer between 0 and 2^32 - 1 inclusive may be represented
- as a 32-bit word. The least significant four bits of the
- integer are represented by the right-most hex digit of the word
- representation. Example: the integer 291 = 2^8+2^5+2^1+2^0 =
- 256+32+2+1 is represented by the hex word 00000123.
-
- The same holds true for an integer between 0 and 2^64-1
- inclusive, which may be represented as a 64-bit word.
-
-
-
-
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-Eastlake 3rd & Hansen Informational [Page 4]
-\f
-RFC 4634 SHAs and HMAC-SHAs July 2006
-
-
- If Z is an integer, 0 <= z < 2^64, then z = (2^32)x + y where 0
- <= x < 2^32 and 0 <= y < 2^32. Since x and y can be represented
- as words X and Y, respectively, z can be represented as the pair
- of words (X,Y).
-
- d. block = 512-bit or 1024-bit string. A block (e.g., B) may be
- represented as a sequence of 32-bit or 64-bit words.
-
-3. Operations on Words
-
- The following logical operators will be applied to words in all four
- hash operations specified herein. SHA-224 and SHA-256 operate on
- 32-bit words, while SHA-384 and SHA-512 operate on 64-bit words.
-
- In the operations below, x<<n is obtained as follows: discard the
- left-most n bits of x and then pad the result with n zeroed bits on
- the right (the result will still be the same number of bits).
-
- a. Bitwise logical word operations
-
- X AND Y = bitwise logical "and" of X and Y.
-
- X OR Y = bitwise logical "inclusive-or" of X and Y.
-
- X XOR Y = bitwise logical "exclusive-or" of X and Y.
-
- NOT X = bitwise logical "complement" of X.
-
- Example:
- 01101100101110011101001001111011
- XOR 01100101110000010110100110110111
- --------------------------------
- = 00001001011110001011101111001100
-
- b. The operation X + Y is defined as follows: words X and Y
- represent w-bit integers x and y, where 0 <= x < 2^w and
- 0 <= y < 2^w. For positive integers n and m, let
-
- n mod m
-
- be the remainder upon dividing n by m. Compute
-
- z = (x + y) mod 2^w.
-
- Then 0 <= z < 2^w. Convert z to a word, Z, and define Z = X +
- Y.
-
-
-
-
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-Eastlake 3rd & Hansen Informational [Page 5]
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-RFC 4634 SHAs and HMAC-SHAs July 2006
-
-
- c. The right shift operation SHR^n(x), where x is a w-bit word and
- n is an integer with 0 <= n < w, is defined by
-
- SHR^n(x) = x>>n
-
- d. The rotate right (circular right shift) operation ROTR^n(x),
- where x is a w-bit word and n is an integer with 0 <= n < w, is
- defined by
-
- ROTR^n(x) = (x>>n) OR (x<<(w-n))
-
- e. The rotate left (circular left shift) operation ROTL^n(x), where
- x is a w-bit word and n is an integer with 0 <= n < w, is
- defined by
-
- ROTL^n(X) = (x<<n) OR (x>>w-n)
-
- Note the following equivalence relationships, where w is fixed
- in each relationship:
-
- ROTL^n(x) = ROTR^(w-x)(x)
-
- ROTR^n(x) = ROTL^(w-n)(x)
-
-4. Message Padding and Parsing
-
- The hash functions specified herein are used to compute a message
- digest for a message or data file that is provided as input. The
- message or data file should be considered to be a bit string. The
- length of the message is the number of bits in the message (the empty
- message has length 0). If the number of bits in a message is a
- multiple of 8, for compactness we can represent the message in hex.
- The purpose of message padding is to make the total length of a
- padded message a multiple of 512 for SHA-224 and SHA-256 or a
- multiple of 1024 for SHA-384 and SHA-512.
-
- The following specifies how this padding shall be performed. As a
- summary, a "1" followed by a number of "0"s followed by a 64-bit or
- 128-bit integer are appended to the end of the message to produce a
- padded message of length 512*n or 1024*n. The minimum number of "0"s
- necessary to meet this criterion is used. The appended integer is
- the length of the original message. The padded message is then
- processed by the hash function as n 512-bit or 1024-bit blocks.
-
-
-
-
-
-
-
-
-Eastlake 3rd & Hansen Informational [Page 6]
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-RFC 4634 SHAs and HMAC-SHAs July 2006
-
-
-4.1. SHA-224 and SHA-256
-
- Suppose a message has length L < 2^64. Before it is input to the
- hash function, the message is padded on the right as follows:
-
- a. "1" is appended. Example: if the original message is
- "01010000", this is padded to "010100001".
-
- b. K "0"s are appended where K is the smallest, non-negative
- solution to the equation
-
- L + 1 + K = 448 (mod 512)
-
- c. Then append the 64-bit block that is L in binary representation.
- After appending this block, the length of the message will be a
- multiple of 512 bits.
-
- Example: Suppose the original message is the bit string
-
- 01100001 01100010 01100011 01100100 01100101
-
- After step (a), this gives
-
- 01100001 01100010 01100011 01100100 01100101 1
-
- Since L = 40, the number of bits in the above is 41 and K = 407
- "0"s are appended, making the total now 448. This gives the
- following in hex:
-
- 61626364 65800000 00000000 00000000
- 00000000 00000000 00000000 00000000
- 00000000 00000000 00000000 00000000
- 00000000 00000000
-
- The 64-bit representation of L = 40 is hex 00000000 00000028.
- Hence the final padded message is the following hex:
-
- 61626364 65800000 00000000 00000000
- 00000000 00000000 00000000 00000000
- 00000000 00000000 00000000 00000000
- 00000000 00000000 00000000 00000028
-
-
-
-
-
-
-
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-Eastlake 3rd & Hansen Informational [Page 7]
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-RFC 4634 SHAs and HMAC-SHAs July 2006
-
-
-4.2. SHA-384 and SHA-512
-
- Suppose a message has length L < 2^128. Before it is input to the
- hash function, the message is padded on the right as follows:
-
- a. "1" is appended. Example: if the original message is
- "01010000", this is padded to "010100001".
-
- b. K "0"s are appended where K is the smallest, non-negative
- solution to the equation
-
- L + 1 + K = 896 (mod 1024)
-
- c. Then append the 128-bit block that is L in binary
- representation. After appending this block, the length of the
- message will be a multiple of 1024 bits.
-
- Example: Suppose the original message is the bit string
-
- 01100001 01100010 01100011 01100100 01100101
-
- After step (a) this gives
-
- 01100001 01100010 01100011 01100100 01100101 1
-
- Since L = 40, the number of bits in the above is 41 and K = 855
- "0"s are appended, making the total now 896. This gives the
- following in hex:
-
- 61626364 65800000 00000000 00000000
- 00000000 00000000 00000000 00000000
- 00000000 00000000 00000000 00000000
- 00000000 00000000 00000000 00000000
- 00000000 00000000 00000000 00000000
- 00000000 00000000 00000000 00000000
- 00000000 00000000 00000000 00000000
-
- The 128-bit representation of L = 40 is hex 00000000 00000000
- 00000000 00000028. Hence the final padded message is the
- following hex:
-
- 61626364 65800000 00000000 00000000
- 00000000 00000000 00000000 00000000
- 00000000 00000000 00000000 00000000
- 00000000 00000000 00000000 00000000
- 00000000 00000000 00000000 00000000
-
-
-
-
-
-Eastlake 3rd & Hansen Informational [Page 8]
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-RFC 4634 SHAs and HMAC-SHAs July 2006
-
-
- 00000000 00000000 00000000 00000000
- 00000000 00000000 00000000 00000000
- 00000000 00000000 00000000 00000028
-
-5. Functions and Constants Used
-
- The following subsections give the six logical functions and the
- table of constants used in each of the hash functions.
-
-5.1. SHA-224 and SHA-256
-
- SHA-224 and SHA-256 use six logical functions, where each function
- operates on 32-bit words, which are represented as x, y, and z. The
- result of each function is a new 32-bit word.
-
- CH( x, y, z) = (x AND y) XOR ( (NOT x) AND z)
-
- MAJ( x, y, z) = (x AND y) XOR (x AND z) XOR (y AND z)
-
- BSIG0(x) = ROTR^2(x) XOR ROTR^13(x) XOR ROTR^22(x)
-
- BSIG1(x) = ROTR^6(x) XOR ROTR^11(x) XOR ROTR^25(x)
-
- SSIG0(x) = ROTR^7(x) XOR ROTR^18(x) XOR SHR^3(x)
-
- SSIG1(x) = ROTR^17(x) XOR ROTR^19(x) XOR SHR^10(x)
-
- SHA-224 and SHA-256 use the same sequence of sixty-four constant
- 32-bit words, K0, K1, ..., K63. These words represent the first
- thirty-two bits of the fractional parts of the cube roots of the
- first sixty-four prime numbers. In hex, these constant words are as
- follows (from left to right):
-
- 428a2f98 71374491 b5c0fbcf e9b5dba5
- 3956c25b 59f111f1 923f82a4 ab1c5ed5
- d807aa98 12835b01 243185be 550c7dc3
- 72be5d74 80deb1fe 9bdc06a7 c19bf174
- e49b69c1 efbe4786 0fc19dc6 240ca1cc
- 2de92c6f 4a7484aa 5cb0a9dc 76f988da
- 983e5152 a831c66d b00327c8 bf597fc7
- c6e00bf3 d5a79147 06ca6351 14292967
- 27b70a85 2e1b2138 4d2c6dfc 53380d13
- 650a7354 766a0abb 81c2c92e 92722c85
- a2bfe8a1 a81a664b c24b8b70 c76c51a3
- d192e819 d6990624 f40e3585 106aa070
- 19a4c116 1e376c08 2748774c 34b0bcb5
-
-
-
-
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-Eastlake 3rd & Hansen Informational [Page 9]
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-RFC 4634 SHAs and HMAC-SHAs July 2006
-
-
- 391c0cb3 4ed8aa4a 5b9cca4f 682e6ff3
- 748f82ee 78a5636f 84c87814 8cc70208
- 90befffa a4506ceb bef9a3f7 c67178f2
-
-5.2. SHA-384 and SHA-512
-
- SHA-384 and SHA-512 each use six logical functions, where each
- function operates on 64-bit words, which are represented as x, y, and
- z. The result of each function is a new 64-bit word.
-
- CH( x, y, z) = (x AND y) XOR ( (NOT x) AND z)
-
- MAJ( x, y, z) = (x AND y) XOR (x AND z) XOR (y AND z)
-
- BSIG0(x) = ROTR^28(x) XOR ROTR^34(x) XOR ROTR^39(x)
-
- BSIG1(x) = ROTR^14(x) XOR ROTR^18(x) XOR ROTR^41(x)
-
- SSIG0(x) = ROTR^1(x) XOR ROTR^8(x) XOR SHR^7(x)
-
- SSIG1(x) = ROTR^19(x) XOR ROTR^61(x) XOR SHR^6(x)
-
- SHA-384 and SHA-512 use the same sequence of eighty constant 64-bit
- words, K0, K1, ... K79. These words represent the first sixty-four
- bits of the fractional parts of the cube roots of the first eighty
- prime numbers. In hex, these constant words are as follows (from
- left to right):
-
- 428a2f98d728ae22 7137449123ef65cd b5c0fbcfec4d3b2f e9b5dba58189dbbc
- 3956c25bf348b538 59f111f1b605d019 923f82a4af194f9b ab1c5ed5da6d8118
- d807aa98a3030242 12835b0145706fbe 243185be4ee4b28c 550c7dc3d5ffb4e2
- 72be5d74f27b896f 80deb1fe3b1696b1 9bdc06a725c71235 c19bf174cf692694
- e49b69c19ef14ad2 efbe4786384f25e3 0fc19dc68b8cd5b5 240ca1cc77ac9c65
- 2de92c6f592b0275 4a7484aa6ea6e483 5cb0a9dcbd41fbd4 76f988da831153b5
- 983e5152ee66dfab a831c66d2db43210 b00327c898fb213f bf597fc7beef0ee4
- c6e00bf33da88fc2 d5a79147930aa725 06ca6351e003826f 142929670a0e6e70
- 27b70a8546d22ffc 2e1b21385c26c926 4d2c6dfc5ac42aed 53380d139d95b3df
- 650a73548baf63de 766a0abb3c77b2a8 81c2c92e47edaee6 92722c851482353b
- a2bfe8a14cf10364 a81a664bbc423001 c24b8b70d0f89791 c76c51a30654be30
- d192e819d6ef5218 d69906245565a910 f40e35855771202a 106aa07032bbd1b8
- 19a4c116b8d2d0c8 1e376c085141ab53 2748774cdf8eeb99 34b0bcb5e19b48a8
- 391c0cb3c5c95a63 4ed8aa4ae3418acb 5b9cca4f7763e373 682e6ff3d6b2b8a3
- 748f82ee5defb2fc 78a5636f43172f60 84c87814a1f0ab72 8cc702081a6439ec
- 90befffa23631e28 a4506cebde82bde9 bef9a3f7b2c67915 c67178f2e372532b
- ca273eceea26619c d186b8c721c0c207 eada7dd6cde0eb1e f57d4f7fee6ed178
- 06f067aa72176fba 0a637dc5a2c898a6 113f9804bef90dae 1b710b35131c471b
- 28db77f523047d84 32caab7b40c72493 3c9ebe0a15c9bebc 431d67c49c100d4c
- 4cc5d4becb3e42b6 597f299cfc657e2a 5fcb6fab3ad6faec 6c44198c4a475817
-
-
-
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-
-
-6. Computing the Message Digest
-
- The output of each of the secure hash functions, after being applied
- to a message of N blocks, is the hash quantity H(N). For SHA-224 and
- SHA-256, H(i) can be considered to be eight 32-bit words, H(i)0,
- H(i)1, ... H(i)7. For SHA-384 and SHA-512, it can be considered to
- be eight 64-bit words, H(i)0, H(i)1, ..., H(i)7.
-
- As described below, the hash words are initialized, modified as each
- message block is processed, and finally concatenated after processing
- the last block to yield the output. For SHA-256 and SHA-512, all of
- the H(N) variables are concatenated while the SHA-224 and SHA-384
- hashes are produced by omitting some from the final concatenation.
-
-6.1. SHA-224 and SHA-256 Initialization
-
- For SHA-224, the initial hash value, H(0), consists of the following
- 32-bit words in hex:
-
- H(0)0 = c1059ed8
- H(0)1 = 367cd507
- H(0)2 = 3070dd17
- H(0)3 = f70e5939
- H(0)4 = ffc00b31
- H(0)5 = 68581511
- H(0)6 = 64f98fa7
- H(0)7 = befa4fa4
-
- For SHA-256, the initial hash value, H(0), consists of the following
- eight 32-bit words, in hex. These words were obtained by taking the
- first thirty-two bits of the fractional parts of the square roots of
- the first eight prime numbers.
-
- H(0)0 = 6a09e667
- H(0)1 = bb67ae85
- H(0)2 = 3c6ef372
- H(0)3 = a54ff53a
- H(0)4 = 510e527f
- H(0)5 = 9b05688c
- H(0)6 = 1f83d9ab
- H(0)7 = 5be0cd19
-
-6.2. SHA-224 and SHA-256 Processing
-
- SHA-224 and SHA-256 perform identical processing on messages blocks
- and differ only in how H(0) is initialized and how they produce their
- final output. They may be used to hash a message, M, having a length
- of L bits, where 0 <= L < 2^64. The algorithm uses (1) a message
-
-
-
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-RFC 4634 SHAs and HMAC-SHAs July 2006
-
-
- schedule of sixty-four 32-bit words, (2) eight working variables of
- 32 bits each, and (3) a hash value of eight 32-bit words.
-
- The words of the message schedule are labeled W0, W1, ..., W63. The
- eight working variables are labeled a, b, c, d, e, f, g, and h. The
- words of the hash value are labeled H(i)0, H(i)1, ..., H(i)7, which
- will hold the initial hash value, H(0), replaced by each successive
- intermediate hash value (after each message block is processed),
- H(i), and ending with the final hash value, H(N), after all N blocks
- are processed. They also use two temporary words, T1 and T2.
-
- The input message is padded as described in Section 4.1 above then
- parsed into 512-bit blocks, which are considered to be composed of 16
- 32-bit words M(i)0, M(i)1, ..., M(i)15. The following computations
- are then performed for each of the N message blocks. All addition is
- performed modulo 2^32.
-
- For i = 1 to N
-
- 1. Prepare the message schedule W:
- For t = 0 to 15
- Wt = M(i)t
- For t = 16 to 63
- Wt = SSIG1(W(t-2)) + W(t-7) + SSIG0(t-15) + W(t-16)
-
- 2. Initialize the working variables:
- a = H(i-1)0
- b = H(i-1)1
- c = H(i-1)2
- d = H(i-1)3
- e = H(i-1)4
- f = H(i-1)5
- g = H(i-1)6
- h = H(i-1)7
-
- 3. Perform the main hash computation:
- For t = 0 to 63
- T1 = h + BSIG1(e) + CH(e,f,g) + Kt + Wt
- T2 = BSIG0(a) + MAJ(a,b,c)
- h = g
- g = f
- f = e
- e = d + T1
- d = c
- c = b
- b = a
- a = T1 + T2
-
-
-
-
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-
-
- 4. Compute the intermediate hash value H(i):
- H(i)0 = a + H(i-1)0
- H(i)1 = b + H(i-1)1
- H(i)2 = c + H(i-1)2
- H(i)3 = d + H(i-1)3
- H(i)4 = e + H(i-1)4
- H(i)5 = f + H(i-1)5
- H(i)6 = g + H(i-1)6
- H(i)7 = h + H(i-1)7
-
- After the above computations have been sequentially performed for all
- of the blocks in the message, the final output is calculated. For
- SHA-256, this is the concatenation of all of H(N)0, H(N)1, through
- H(N)7. For SHA-224, this is the concatenation of H(N)0, H(N)1,
- through H(N)6.
-
-6.3. SHA-384 and SHA-512 Initialization
-
- For SHA-384, the initial hash value, H(0), consists of the following
- eight 64-bit words, in hex. These words were obtained by taking the
- first sixty-four bits of the fractional parts of the square roots of
- the ninth through sixteenth prime numbers.
-
- H(0)0 = cbbb9d5dc1059ed8
- H(0)1 = 629a292a367cd507
- H(0)2 = 9159015a3070dd17
- H(0)3 = 152fecd8f70e5939
- H(0)4 = 67332667ffc00b31
- H(0)5 = 8eb44a8768581511
- H(0)6 = db0c2e0d64f98fa7
- H(0)7 = 47b5481dbefa4fa4
-
- For SHA-512, the initial hash value, H(0), consists of the following
- eight 64-bit words, in hex. These words were obtained by taking the
- first sixty-four bits of the fractional parts of the square roots of
- the first eight prime numbers.
-
- H(0)0 = 6a09e667f3bcc908
- H(0)1 = bb67ae8584caa73b
- H(0)2 = 3c6ef372fe94f82b
- H(0)3 = a54ff53a5f1d36f1
- H(0)4 = 510e527fade682d1
- H(0)5 = 9b05688c2b3e6c1f
- H(0)6 = 1f83d9abfb41bd6b
- H(0)7 = 5be0cd19137e2179
-
-
-
-
-
-
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-
-
-6.4. SHA-384 and SHA-512 Processing
-
- SHA-384 and SHA-512 perform identical processing on message blocks
- and differ only in how H(0) is initialized and how they produce their
- final output. They may be used to hash a message, M, having a length
- of L bits, where 0 <= L < 2^128. The algorithm uses (1) a message
- schedule of eighty 64-bit words, (2) eight working variables of 64
- bits each, and (3) a hash value of eight 64-bit words.
-
- The words of the message schedule are labeled W0, W1, ..., W79. The
- eight working variables are labeled a, b, c, d, e, f, g, and h. The
- words of the hash value are labeled H(i)0, H(i)1, ..., H(i)7, which
- will hold the initial hash value, H(0), replaced by each successive
- intermediate hash value (after each message block is processed),
- H(i), and ending with the final hash value, H(N) after all N blocks
- are processed.
-
- The input message is padded as described in Section 4.2 above, then
- parsed into 1024-bit blocks, which are considered to be composed of
- 16 64-bit words M(i)0, M(i)1, ..., M(i)15. The following
- computations are then performed for each of the N message blocks.
- All addition is performed modulo 2^64.
-
- For i = 1 to N
-
- 1. Prepare the message schedule W:
- For t = 0 to 15
- Wt = M(i)t
- For t = 16 to 79
- Wt = SSIG1(W(t-2)) + W(t-7) + SSIG0(t-15) + W(t-16)
-
- 2. Initialize the working variables:
- a = H(i-1)0
- b = H(i-1)1
- c = H(i-1)2
- d = H(i-1)3
- e = H(i-1)4
- f = H(i-1)5
- g = H(i-1)6
- h = H(i-1)7
-
- 3. Perform the main hash computation:
- For t = 0 to 79
- T1 = h + BSIG1(e) + CH(e,f,g) + Kt + Wt
- T2 = BSIG0(a) + MAJ(a,b,c)
- h = g
- g = f
- f = e
-
-
-
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-RFC 4634 SHAs and HMAC-SHAs July 2006
-
-
- e = d + T1
- d = c
- c = b
- b = a
- a = T1 + T2
-
- 4. Compute the intermediate hash value H(i):
- H(i)0 = a + H(i-1)0
- H(i)1 = b + H(i-1)1
- H(i)2 = c + H(i-1)2
- H(i)3 = d + H(i-1)3
- H(i)4 = e + H(i-1)4
- H(i)5 = f + H(i-1)5
- H(i)6 = g + H(i-1)6
- H(i)7 = h + H(i-1)7
-
- After the above computations have been sequentially performed for all
- of the blocks in the message, the final output is calculated. For
- SHA-512, this is the concatenation of all of H(N)0, H(N)1, through
- H(N)7. For SHA-384, this is the concatenation of H(N)0, H(N)1,
- through H(N)5.
-
-7. SHA-Based HMACs
-
- HMAC is a method for computing a keyed MAC (message authentication
- code) using a hash function as described in [RFC2104]. It uses a key
- to mix in with the input text to produce the final hash.
-
- Sample code is also provided, in Section 8.3 below, to perform HMAC
- based on any of the SHA algorithms described herein. The sample code
- found in [RFC2104] was written in terms of a specified text size.
- Since SHA is defined in terms of an arbitrary number of bits, the
- sample HMAC code has been written to allow the text input to HMAC to
- have an arbitrary number of octets and bits. A fixed-length
- interface is also provided.
-
-8. C Code for SHAs
-
- Below is a demonstration implementation of these secure hash
- functions in C. Section 8.1 contains the header file sha.h, which
- declares all constants, structures, and functions used by the sha and
- hmac functions. Section 8.2 contains the C code for sha1.c,
- sha224-256.c, sha384-512.c, and usha.c along with sha-private.h,
- which provides some declarations common to all the sha functions.
- Section 8.3 contains the C code for the hmac functions. Section 8.4
- contains a test driver to exercise the code.
-
-
-
-
-
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-RFC 4634 SHAs and HMAC-SHAs July 2006
-
-
- For each of the digest length $$$, there is the following set of
- constants, a structure, and functions:
-
- Constants:
- SHA$$$HashSize number of octets in the hash
- SHA$$$HashSizeBits number of bits in the hash
- SHA$$$_Message_Block_Size
- number of octets used in the intermediate
- message blocks
- shaSuccess = 0 constant returned by each function on success
- shaNull = 1 constant returned by each function when
- presented with a null pointer parameter
- shaInputTooLong = 2 constant returned by each function when the
- input data is too long
- shaStateError constant returned by each function when
- SHA$$$Input is called after SHA$$$FinalBits or
- SHA$$$Result.
-
- Structure:
- typedef SHA$$$Context
- an opaque structure holding the complete state
- for producing the hash
-
- Functions:
- int SHA$$$Reset(SHA$$$Context *);
- Reset the hash context state
- int SHA$$$Input(SHA$$$Context *, const uint8_t *octets,
- unsigned int bytecount);
- Incorporate bytecount octets into the hash.
- int SHA$$$FinalBits(SHA$$$Context *, const uint8_t octet,
- unsigned int bitcount);
- Incorporate bitcount bits into the hash. The bits are in
- the upper portion of the octet. SHA$$$Input() cannot be
- called after this.
- int SHA$$$Result(SHA$$$Context *,
- uint8_t Message_Digest[SHA$$$HashSize]);
- Do the final calculations on the hash and copy the value
- into Message_Digest.
-
- In addition, functions with the prefix USHA are provided that take a
- SHAversion value (SHA$$$) to select the SHA function suite. They add
- the following constants, structure, and functions:
-
- Constants:
- shaBadParam constant returned by USHA functions when
- presented with a bad SHAversion (SHA$$$)
- parameter
-
-
-
-
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-RFC 4634 SHAs and HMAC-SHAs July 2006
-
-
- SHA$$$ SHAversion enumeration values, used by usha
- and hmac functions to select the SHA function
- suite
-
- Structure:
- typedef USHAContext
- an opaque structure holding the complete state
- for producing the hash
-
- Functions:
- int USHAReset(USHAContext *, SHAversion whichSha);
- Reset the hash context state.
- int USHAInput(USHAContext *,
- const uint8_t *bytes, unsigned int bytecount);
- Incorporate bytecount octets into the hash.
- int USHAFinalBits(USHAContext *,
- const uint8_t bits, unsigned int bitcount);
- Incorporate bitcount bits into the hash.
- int USHAResult(USHAContext *,
- uint8_t Message_Digest[USHAMaxHashSize]);
- Do the final calculations on the hash and copy the value
- into Message_Digest. Octets in Message_Digest beyond
- USHAHashSize(whichSha) are left untouched.
- int USHAHashSize(enum SHAversion whichSha);
- The number of octets in the given hash.
- int USHAHashSizeBits(enum SHAversion whichSha);
- The number of bits in the given hash.
- int USHABlockSize(enum SHAversion whichSha);
- The internal block size for the given hash.
-
- The hmac functions follow the same pattern to allow any length of
- text input to be used.
-
- Structure:
- typedef HMACContext an opaque structure holding the complete state
- for producing the hash
-
- Functions:
- int hmacReset(HMACContext *ctx, enum SHAversion whichSha,
- const unsigned char *key, int key_len);
- Reset the hash context state.
- int hmacInput(HMACContext *ctx, const unsigned char *text,
- int text_len);
- Incorporate text_len octets into the hash.
- int hmacFinalBits(HMACContext *ctx, const uint8_t bits,
- unsigned int bitcount);
- Incorporate bitcount bits into the hash.
-
-
-
-
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-
-
- int hmacResult(HMACContext *ctx,
- uint8_t Message_Digest[USHAMaxHashSize]);
- Do the final calculations on the hash and copy the value
- into Message_Digest. Octets in Message_Digest beyond
- USHAHashSize(whichSha) are left untouched.
-
- In addition, a combined interface is provided, similar to that shown
- in RFC 2104, that allows a fixed-length text input to be used.
-
- int hmac(SHAversion whichSha,
- const unsigned char *text, int text_len,
- const unsigned char *key, int key_len,
- uint8_t Message_Digest[USHAMaxHashSize]);
- Calculate the given digest for the given text and key, and
- return the resulting hash. Octets in Message_Digest beyond
- USHAHashSize(whichSha) are left untouched.
-
-8.1. The .h File
-
-/**************************** sha.h ****************************/
-/******************* See RFC 4634 for details ******************/
-#ifndef _SHA_H_
-#define _SHA_H_
-
-/*
- * Description:
- * This file implements the Secure Hash Signature Standard
- * algorithms as defined in the National Institute of Standards
- * and Technology Federal Information Processing Standards
- * Publication (FIPS PUB) 180-1 published on April 17, 1995, 180-2
- * published on August 1, 2002, and the FIPS PUB 180-2 Change
- * Notice published on February 28, 2004.
- *
- * A combined document showing all algorithms is available at
- * http://csrc.nist.gov/publications/fips/
- * fips180-2/fips180-2withchangenotice.pdf
- *
- * The five hashes are defined in these sizes:
- * SHA-1 20 byte / 160 bit
- * SHA-224 28 byte / 224 bit
- * SHA-256 32 byte / 256 bit
- * SHA-384 48 byte / 384 bit
- * SHA-512 64 byte / 512 bit
- */
-
-#include <stdint.h>
-/*
- * If you do not have the ISO standard stdint.h header file, then you
-
-
-
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-
-
- * must typedef the following:
- * name meaning
- * uint64_t unsigned 64 bit integer
- * uint32_t unsigned 32 bit integer
- * uint8_t unsigned 8 bit integer (i.e., unsigned char)
- * int_least16_t integer of >= 16 bits
- *
- */
-
-#ifndef _SHA_enum_
-#define _SHA_enum_
-/*
- * All SHA functions return one of these values.
- */
-enum {
- shaSuccess = 0,
- shaNull, /* Null pointer parameter */
- shaInputTooLong, /* input data too long */
- shaStateError, /* called Input after FinalBits or Result */
- shaBadParam /* passed a bad parameter */
-};
-#endif /* _SHA_enum_ */
-
-/*
- * These constants hold size information for each of the SHA
- * hashing operations
- */
-enum {
- SHA1_Message_Block_Size = 64, SHA224_Message_Block_Size = 64,
- SHA256_Message_Block_Size = 64, SHA384_Message_Block_Size = 128,
- SHA512_Message_Block_Size = 128,
- USHA_Max_Message_Block_Size = SHA512_Message_Block_Size,
-
- SHA1HashSize = 20, SHA224HashSize = 28, SHA256HashSize = 32,
- SHA384HashSize = 48, SHA512HashSize = 64,
- USHAMaxHashSize = SHA512HashSize,
-
- SHA1HashSizeBits = 160, SHA224HashSizeBits = 224,
- SHA256HashSizeBits = 256, SHA384HashSizeBits = 384,
- SHA512HashSizeBits = 512, USHAMaxHashSizeBits = SHA512HashSizeBits
-};
-
-/*
- * These constants are used in the USHA (unified sha) functions.
- */
-typedef enum SHAversion {
- SHA1, SHA224, SHA256, SHA384, SHA512
-} SHAversion;
-
-
-
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-
-
-/*
- * This structure will hold context information for the SHA-1
- * hashing operation.
- */
-typedef struct SHA1Context {
- uint32_t Intermediate_Hash[SHA1HashSize/4]; /* Message Digest */
-
- uint32_t Length_Low; /* Message length in bits */
- uint32_t Length_High; /* Message length in bits */
-
- int_least16_t Message_Block_Index; /* Message_Block array index */
- /* 512-bit message blocks */
- uint8_t Message_Block[SHA1_Message_Block_Size];
-
- int Computed; /* Is the digest computed? */
- int Corrupted; /* Is the digest corrupted? */
-} SHA1Context;
-
-/*
- * This structure will hold context information for the SHA-256
- * hashing operation.
- */
-typedef struct SHA256Context {
- uint32_t Intermediate_Hash[SHA256HashSize/4]; /* Message Digest */
-
- uint32_t Length_Low; /* Message length in bits */
- uint32_t Length_High; /* Message length in bits */
-
- int_least16_t Message_Block_Index; /* Message_Block array index */
- /* 512-bit message blocks */
- uint8_t Message_Block[SHA256_Message_Block_Size];
-
- int Computed; /* Is the digest computed? */
- int Corrupted; /* Is the digest corrupted? */
-} SHA256Context;
-
-/*
- * This structure will hold context information for the SHA-512
- * hashing operation.
- */
-typedef struct SHA512Context {
-#ifdef USE_32BIT_ONLY
- uint32_t Intermediate_Hash[SHA512HashSize/4]; /* Message Digest */
- uint32_t Length[4]; /* Message length in bits */
-#else /* !USE_32BIT_ONLY */
- uint64_t Intermediate_Hash[SHA512HashSize/8]; /* Message Digest */
- uint64_t Length_Low, Length_High; /* Message length in bits */
-#endif /* USE_32BIT_ONLY */
-
-
-
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-
-
- int_least16_t Message_Block_Index; /* Message_Block array index */
- /* 1024-bit message blocks */
- uint8_t Message_Block[SHA512_Message_Block_Size];
-
- int Computed; /* Is the digest computed?*/
- int Corrupted; /* Is the digest corrupted? */
-} SHA512Context;
-
-/*
- * This structure will hold context information for the SHA-224
- * hashing operation. It uses the SHA-256 structure for computation.
- */
-typedef struct SHA256Context SHA224Context;
-
-/*
- * This structure will hold context information for the SHA-384
- * hashing operation. It uses the SHA-512 structure for computation.
- */
-typedef struct SHA512Context SHA384Context;
-
-/*
- * This structure holds context information for all SHA
- * hashing operations.
- */
-typedef struct USHAContext {
- int whichSha; /* which SHA is being used */
- union {
- SHA1Context sha1Context;
- SHA224Context sha224Context; SHA256Context sha256Context;
- SHA384Context sha384Context; SHA512Context sha512Context;
- } ctx;
-} USHAContext;
-
-/*
- * This structure will hold context information for the HMAC
- * keyed hashing operation.
- */
-typedef struct HMACContext {
- int whichSha; /* which SHA is being used */
- int hashSize; /* hash size of SHA being used */
- int blockSize; /* block size of SHA being used */
- USHAContext shaContext; /* SHA context */
- unsigned char k_opad[USHA_Max_Message_Block_Size];
- /* outer padding - key XORd with opad */
-} HMACContext;
-
-
-
-
-
-
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-
-
-/*
- * Function Prototypes
- */
-
-/* SHA-1 */
-extern int SHA1Reset(SHA1Context *);
-extern int SHA1Input(SHA1Context *, const uint8_t *bytes,
- unsigned int bytecount);
-extern int SHA1FinalBits(SHA1Context *, const uint8_t bits,
- unsigned int bitcount);
-extern int SHA1Result(SHA1Context *,
- uint8_t Message_Digest[SHA1HashSize]);
-
-/* SHA-224 */
-extern int SHA224Reset(SHA224Context *);
-extern int SHA224Input(SHA224Context *, const uint8_t *bytes,
- unsigned int bytecount);
-extern int SHA224FinalBits(SHA224Context *, const uint8_t bits,
- unsigned int bitcount);
-extern int SHA224Result(SHA224Context *,
- uint8_t Message_Digest[SHA224HashSize]);
-
-/* SHA-256 */
-extern int SHA256Reset(SHA256Context *);
-extern int SHA256Input(SHA256Context *, const uint8_t *bytes,
- unsigned int bytecount);
-extern int SHA256FinalBits(SHA256Context *, const uint8_t bits,
- unsigned int bitcount);
-extern int SHA256Result(SHA256Context *,
- uint8_t Message_Digest[SHA256HashSize]);
-
-/* SHA-384 */
-extern int SHA384Reset(SHA384Context *);
-extern int SHA384Input(SHA384Context *, const uint8_t *bytes,
- unsigned int bytecount);
-extern int SHA384FinalBits(SHA384Context *, const uint8_t bits,
- unsigned int bitcount);
-extern int SHA384Result(SHA384Context *,
- uint8_t Message_Digest[SHA384HashSize]);
-
-/* SHA-512 */
-extern int SHA512Reset(SHA512Context *);
-extern int SHA512Input(SHA512Context *, const uint8_t *bytes,
- unsigned int bytecount);
-extern int SHA512FinalBits(SHA512Context *, const uint8_t bits,
- unsigned int bitcount);
-extern int SHA512Result(SHA512Context *,
- uint8_t Message_Digest[SHA512HashSize]);
-
-
-
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-
-
-/* Unified SHA functions, chosen by whichSha */
-extern int USHAReset(USHAContext *, SHAversion whichSha);
-extern int USHAInput(USHAContext *,
- const uint8_t *bytes, unsigned int bytecount);
-extern int USHAFinalBits(USHAContext *,
- const uint8_t bits, unsigned int bitcount);
-extern int USHAResult(USHAContext *,
- uint8_t Message_Digest[USHAMaxHashSize]);
-extern int USHABlockSize(enum SHAversion whichSha);
-extern int USHAHashSize(enum SHAversion whichSha);
-extern int USHAHashSizeBits(enum SHAversion whichSha);
-
-/*
- * HMAC Keyed-Hashing for Message Authentication, RFC2104,
- * for all SHAs.
- * This interface allows a fixed-length text input to be used.
- */
-extern int hmac(SHAversion whichSha, /* which SHA algorithm to use */
- const unsigned char *text, /* pointer to data stream */
- int text_len, /* length of data stream */
- const unsigned char *key, /* pointer to authentication key */
- int key_len, /* length of authentication key */
- uint8_t digest[USHAMaxHashSize]); /* caller digest to fill in */
-
-/*
- * HMAC Keyed-Hashing for Message Authentication, RFC2104,
- * for all SHAs.
- * This interface allows any length of text input to be used.
- */
-extern int hmacReset(HMACContext *ctx, enum SHAversion whichSha,
- const unsigned char *key, int key_len);
-extern int hmacInput(HMACContext *ctx, const unsigned char *text,
- int text_len);
-
-extern int hmacFinalBits(HMACContext *ctx, const uint8_t bits,
- unsigned int bitcount);
-extern int hmacResult(HMACContext *ctx,
- uint8_t digest[USHAMaxHashSize]);
-
-#endif /* _SHA_H_ */
-
-
-
-
-
-
-
-
-
-
-
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-
-
-8.2. The SHA Code
-
- This code is primarily intended as expository and could be optimized
- further. For example, the assignment rotations through the variables
- a, b, ..., h could be treated as a cycle and the loop unrolled,
- rather than doing the explicit copying.
-
- Note that there are alternative representations of the Ch() and Maj()
- functions controlled by an ifdef.
-
-8.2.1. sha1.c
-
-/**************************** sha1.c ****************************/
-/******************** See RFC 4634 for details ******************/
-/*
- * Description:
- * This file implements the Secure Hash Signature Standard
- * algorithms as defined in the National Institute of Standards
- * and Technology Federal Information Processing Standards
- * Publication (FIPS PUB) 180-1 published on April 17, 1995, 180-2
- * published on August 1, 2002, and the FIPS PUB 180-2 Change
- * Notice published on February 28, 2004.
- *
- * A combined document showing all algorithms is available at
- * http://csrc.nist.gov/publications/fips/
- * fips180-2/fips180-2withchangenotice.pdf
- *
- * The SHA-1 algorithm produces a 160-bit message digest for a
- * given data stream. It should take about 2**n steps to find a
- * message with the same digest as a given message and
- * 2**(n/2) to find any two messages with the same digest,
- * when n is the digest size in bits. Therefore, this
- * algorithm can serve as a means of providing a
- * "fingerprint" for a message.
- *
- * Portability Issues:
- * SHA-1 is defined in terms of 32-bit "words". This code
- * uses <stdint.h> (included via "sha.h") to define 32 and 8
- * bit unsigned integer types. If your C compiler does not
- * support 32 bit unsigned integers, this code is not
- * appropriate.
- *
- * Caveats:
- * SHA-1 is designed to work with messages less than 2^64 bits
- * long. This implementation uses SHA1Input() to hash the bits
- * that are a multiple of the size of an 8-bit character, and then
- * uses SHA1FinalBits() to hash the final few bits of the input.
- */
-
-
-
-Eastlake 3rd & Hansen Informational [Page 24]
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-RFC 4634 SHAs and HMAC-SHAs July 2006
-
-
-#include "sha.h"
-#include "sha-private.h"
-
-/*
- * Define the SHA1 circular left shift macro
- */
-#define SHA1_ROTL(bits,word) \
- (((word) << (bits)) | ((word) >> (32-(bits))))
-
-/*
- * add "length" to the length
- */
-static uint32_t addTemp;
-#define SHA1AddLength(context, length) \
- (addTemp = (context)->Length_Low, \
- (context)->Corrupted = \
- (((context)->Length_Low += (length)) < addTemp) && \
- (++(context)->Length_High == 0) ? 1 : 0)
-
-/* Local Function Prototypes */
-static void SHA1Finalize(SHA1Context *context, uint8_t Pad_Byte);
-static void SHA1PadMessage(SHA1Context *, uint8_t Pad_Byte);
-static void SHA1ProcessMessageBlock(SHA1Context *);
-
-/*
- * SHA1Reset
- *
- * Description:
- * This function will initialize the SHA1Context in preparation
- * for computing a new SHA1 message digest.
- *
- * Parameters:
- * context: [in/out]
- * The context to reset.
- *
- * Returns:
- * sha Error Code.
- *
- */
-int SHA1Reset(SHA1Context *context)
-{
- if (!context)
- return shaNull;
-
- context->Length_Low = 0;
- context->Length_High = 0;
- context->Message_Block_Index = 0;
-
-
-
-
-Eastlake 3rd & Hansen Informational [Page 25]
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-
-
- /* Initial Hash Values: FIPS-180-2 section 5.3.1 */
- context->Intermediate_Hash[0] = 0x67452301;
- context->Intermediate_Hash[1] = 0xEFCDAB89;
- context->Intermediate_Hash[2] = 0x98BADCFE;
- context->Intermediate_Hash[3] = 0x10325476;
- context->Intermediate_Hash[4] = 0xC3D2E1F0;
-
- context->Computed = 0;
- context->Corrupted = 0;
-
- return shaSuccess;
-}
-
-/*
- * SHA1Input
- *
- * Description:
- * This function accepts an array of octets as the next portion
- * of the message.
- *
- * Parameters:
- * context: [in/out]
- * The SHA context to update
- * message_array: [in]
- * An array of characters representing the next portion of
- * the message.
- * length: [in]
- * The length of the message in message_array
- *
- * Returns:
- * sha Error Code.
- *
- */
-int SHA1Input(SHA1Context *context,
- const uint8_t *message_array, unsigned length)
-{
- if (!length)
- return shaSuccess;
-
- if (!context || !message_array)
- return shaNull;
-
- if (context->Computed) {
- context->Corrupted = shaStateError;
- return shaStateError;
- }
-
- if (context->Corrupted)
-
-
-
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-
-
- return context->Corrupted;
-
- while (length-- && !context->Corrupted) {
- context->Message_Block[context->Message_Block_Index++] =
- (*message_array & 0xFF);
-
- if (!SHA1AddLength(context, 8) &&
- (context->Message_Block_Index == SHA1_Message_Block_Size))
- SHA1ProcessMessageBlock(context);
-
- message_array++;
- }
-
- return shaSuccess;
-}
-
-/*
- * SHA1FinalBits
- *
- * Description:
- * This function will add in any final bits of the message.
- *
- * Parameters:
- * context: [in/out]
- * The SHA context to update
- * message_bits: [in]
- * The final bits of the message, in the upper portion of the
- * byte. (Use 0b###00000 instead of 0b00000### to input the
- * three bits ###.)
- * length: [in]
- * The number of bits in message_bits, between 1 and 7.
- *
- * Returns:
- * sha Error Code.
- */
-int SHA1FinalBits(SHA1Context *context, const uint8_t message_bits,
- unsigned int length)
-{
- uint8_t masks[8] = {
- /* 0 0b00000000 */ 0x00, /* 1 0b10000000 */ 0x80,
- /* 2 0b11000000 */ 0xC0, /* 3 0b11100000 */ 0xE0,
- /* 4 0b11110000 */ 0xF0, /* 5 0b11111000 */ 0xF8,
- /* 6 0b11111100 */ 0xFC, /* 7 0b11111110 */ 0xFE
- };
- uint8_t markbit[8] = {
- /* 0 0b10000000 */ 0x80, /* 1 0b01000000 */ 0x40,
- /* 2 0b00100000 */ 0x20, /* 3 0b00010000 */ 0x10,
- /* 4 0b00001000 */ 0x08, /* 5 0b00000100 */ 0x04,
-
-
-
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-
-
- /* 6 0b00000010 */ 0x02, /* 7 0b00000001 */ 0x01
- };
-
- if (!length)
- return shaSuccess;
-
- if (!context)
- return shaNull;
-
- if (context->Computed || (length >= 8) || (length == 0)) {
- context->Corrupted = shaStateError;
- return shaStateError;
- }
-
- if (context->Corrupted)
- return context->Corrupted;
-
- SHA1AddLength(context, length);
- SHA1Finalize(context,
- (uint8_t) ((message_bits & masks[length]) | markbit[length]));
-
- return shaSuccess;
-}
-
-/*
- * SHA1Result
- *
- * Description:
- * This function will return the 160-bit message digest into the
- * Message_Digest array provided by the caller.
- * NOTE: The first octet of hash is stored in the 0th element,
- * the last octet of hash in the 19th element.
- *
- * Parameters:
- * context: [in/out]
- * The context to use to calculate the SHA-1 hash.
- * Message_Digest: [out]
- * Where the digest is returned.
- *
- * Returns:
- * sha Error Code.
- *
- */
-int SHA1Result(SHA1Context *context,
- uint8_t Message_Digest[SHA1HashSize])
-{
- int i;
-
-
-
-
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-
-
- if (!context || !Message_Digest)
- return shaNull;
-
- if (context->Corrupted)
- return context->Corrupted;
-
- if (!context->Computed)
- SHA1Finalize(context, 0x80);
-
- for (i = 0; i < SHA1HashSize; ++i)
- Message_Digest[i] = (uint8_t) (context->Intermediate_Hash[i>>2]
- >> 8 * ( 3 - ( i & 0x03 ) ));
-
- return shaSuccess;
-}
-
-/*
- * SHA1Finalize
- *
- * Description:
- * This helper function finishes off the digest calculations.
- *
- * Parameters:
- * context: [in/out]
- * The SHA context to update
- * Pad_Byte: [in]
- * The last byte to add to the digest before the 0-padding
- * and length. This will contain the last bits of the message
- * followed by another single bit. If the message was an
- * exact multiple of 8-bits long, Pad_Byte will be 0x80.
- *
- * Returns:
- * sha Error Code.
- *
- */
-static void SHA1Finalize(SHA1Context *context, uint8_t Pad_Byte)
-{
- int i;
- SHA1PadMessage(context, Pad_Byte);
- /* message may be sensitive, clear it out */
- for (i = 0; i < SHA1_Message_Block_Size; ++i)
- context->Message_Block[i] = 0;
- context->Length_Low = 0; /* and clear length */
- context->Length_High = 0;
- context->Computed = 1;
-}
-
-/*
-
-
-
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-
-
- * SHA1PadMessage
- *
- * Description:
- * According to the standard, the message must be padded to an
- * even 512 bits. The first padding bit must be a '1'. The last
- * 64 bits represent the length of the original message. All bits
- * in between should be 0. This helper function will pad the
- * message according to those rules by filling the Message_Block
- * array accordingly. When it returns, it can be assumed that the
- * message digest has been computed.
- *
- * Parameters:
- * context: [in/out]
- * The context to pad
- * Pad_Byte: [in]
- * The last byte to add to the digest before the 0-padding
- * and length. This will contain the last bits of the message
- * followed by another single bit. If the message was an
- * exact multiple of 8-bits long, Pad_Byte will be 0x80.
- *
- * Returns:
- * Nothing.
- */
-static void SHA1PadMessage(SHA1Context *context, uint8_t Pad_Byte)
-{
- /*
- * Check to see if the current message block is too small to hold
- * the initial padding bits and length. If so, we will pad the
- * block, process it, and then continue padding into a second
- * block.
- */
- if (context->Message_Block_Index >= (SHA1_Message_Block_Size - 8)) {
- context->Message_Block[context->Message_Block_Index++] = Pad_Byte;
- while (context->Message_Block_Index < SHA1_Message_Block_Size)
- context->Message_Block[context->Message_Block_Index++] = 0;
-
- SHA1ProcessMessageBlock(context);
- } else
- context->Message_Block[context->Message_Block_Index++] = Pad_Byte;
-
- while (context->Message_Block_Index < (SHA1_Message_Block_Size - 8))
- context->Message_Block[context->Message_Block_Index++] = 0;
-
- /*
- * Store the message length as the last 8 octets
- */
- context->Message_Block[56] = (uint8_t) (context->Length_High >> 24);
- context->Message_Block[57] = (uint8_t) (context->Length_High >> 16);
-
-
-
-Eastlake 3rd & Hansen Informational [Page 30]
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-
-
- context->Message_Block[58] = (uint8_t) (context->Length_High >> 8);
- context->Message_Block[59] = (uint8_t) (context->Length_High);
- context->Message_Block[60] = (uint8_t) (context->Length_Low >> 24);
- context->Message_Block[61] = (uint8_t) (context->Length_Low >> 16);
- context->Message_Block[62] = (uint8_t) (context->Length_Low >> 8);
- context->Message_Block[63] = (uint8_t) (context->Length_Low);
-
- SHA1ProcessMessageBlock(context);
-}
-
-/*
- * SHA1ProcessMessageBlock
- *
- * Description:
- * This helper function will process the next 512 bits of the
- * message stored in the Message_Block array.
- *
- * Parameters:
- * None.
- *
- * Returns:
- * Nothing.
- *
- * Comments:
- * Many of the variable names in this code, especially the
- * single character names, were used because those were the
- * names used in the publication.
- */
-static void SHA1ProcessMessageBlock(SHA1Context *context)
-{
- /* Constants defined in FIPS-180-2, section 4.2.1 */
- const uint32_t K[4] = {
- 0x5A827999, 0x6ED9EBA1, 0x8F1BBCDC, 0xCA62C1D6
- };
- int t; /* Loop counter */
- uint32_t temp; /* Temporary word value */
- uint32_t W[80]; /* Word sequence */
- uint32_t A, B, C, D, E; /* Word buffers */
-
- /*
- * Initialize the first 16 words in the array W
- */
- for (t = 0; t < 16; t++) {
- W[t] = ((uint32_t)context->Message_Block[t * 4]) << 24;
- W[t] |= ((uint32_t)context->Message_Block[t * 4 + 1]) << 16;
- W[t] |= ((uint32_t)context->Message_Block[t * 4 + 2]) << 8;
- W[t] |= ((uint32_t)context->Message_Block[t * 4 + 3]);
- }
-
-
-
-Eastlake 3rd & Hansen Informational [Page 31]
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-
-
- for (t = 16; t < 80; t++)
- W[t] = SHA1_ROTL(1, W[t-3] ^ W[t-8] ^ W[t-14] ^ W[t-16]);
-
- A = context->Intermediate_Hash[0];
- B = context->Intermediate_Hash[1];
- C = context->Intermediate_Hash[2];
- D = context->Intermediate_Hash[3];
- E = context->Intermediate_Hash[4];
-
- for (t = 0; t < 20; t++) {
- temp = SHA1_ROTL(5,A) + SHA_Ch(B, C, D) + E + W[t] + K[0];
- E = D;
- D = C;
- C = SHA1_ROTL(30,B);
- B = A;
- A = temp;
- }
-
- for (t = 20; t < 40; t++) {
- temp = SHA1_ROTL(5,A) + SHA_Parity(B, C, D) + E + W[t] + K[1];
- E = D;
- D = C;
- C = SHA1_ROTL(30,B);
- B = A;
- A = temp;
- }
-
- for (t = 40; t < 60; t++) {
- temp = SHA1_ROTL(5,A) + SHA_Maj(B, C, D) + E + W[t] + K[2];
- E = D;
- D = C;
- C = SHA1_ROTL(30,B);
- B = A;
- A = temp;
- }
-
- for (t = 60; t < 80; t++) {
- temp = SHA1_ROTL(5,A) + SHA_Parity(B, C, D) + E + W[t] + K[3];
- E = D;
- D = C;
- C = SHA1_ROTL(30,B);
- B = A;
- A = temp;
- }
-
- context->Intermediate_Hash[0] += A;
- context->Intermediate_Hash[1] += B;
- context->Intermediate_Hash[2] += C;
-
-
-
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-
-
- context->Intermediate_Hash[3] += D;
- context->Intermediate_Hash[4] += E;
-
- context->Message_Block_Index = 0;
-}
-
-8.2.2. sha224-256.c
-
-/*************************** sha224-256.c ***************************/
-/********************* See RFC 4634 for details *********************/
-/*
- * Description:
- * This file implements the Secure Hash Signature Standard
- * algorithms as defined in the National Institute of Standards
- * and Technology Federal Information Processing Standards
- * Publication (FIPS PUB) 180-1 published on April 17, 1995, 180-2
- * published on August 1, 2002, and the FIPS PUB 180-2 Change
- * Notice published on February 28, 2004.
- *
- * A combined document showing all algorithms is available at
- * http://csrc.nist.gov/publications/fips/
- * fips180-2/fips180-2withchangenotice.pdf
- *
- * The SHA-224 and SHA-256 algorithms produce 224-bit and 256-bit
- * message digests for a given data stream. It should take about
- * 2**n steps to find a message with the same digest as a given
- * message and 2**(n/2) to find any two messages with the same
- * digest, when n is the digest size in bits. Therefore, this
- * algorithm can serve as a means of providing a
- * "fingerprint" for a message.
- *
- * Portability Issues:
- * SHA-224 and SHA-256 are defined in terms of 32-bit "words".
- * This code uses <stdint.h> (included via "sha.h") to define 32
- * and 8 bit unsigned integer types. If your C compiler does not
- * support 32 bit unsigned integers, this code is not
- * appropriate.
- *
- * Caveats:
- * SHA-224 and SHA-256 are designed to work with messages less
- * than 2^64 bits long. This implementation uses SHA224/256Input()
- * to hash the bits that are a multiple of the size of an 8-bit
- * character, and then uses SHA224/256FinalBits() to hash the
- * final few bits of the input.
- */
-
-#include "sha.h"
-#include "sha-private.h"
-
-
-
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-
-
-/* Define the SHA shift, rotate left and rotate right macro */
-#define SHA256_SHR(bits,word) ((word) >> (bits))
-#define SHA256_ROTL(bits,word) \
- (((word) << (bits)) | ((word) >> (32-(bits))))
-#define SHA256_ROTR(bits,word) \
- (((word) >> (bits)) | ((word) << (32-(bits))))
-
-/* Define the SHA SIGMA and sigma macros */
-#define SHA256_SIGMA0(word) \
- (SHA256_ROTR( 2,word) ^ SHA256_ROTR(13,word) ^ SHA256_ROTR(22,word))
-#define SHA256_SIGMA1(word) \
- (SHA256_ROTR( 6,word) ^ SHA256_ROTR(11,word) ^ SHA256_ROTR(25,word))
-#define SHA256_sigma0(word) \
- (SHA256_ROTR( 7,word) ^ SHA256_ROTR(18,word) ^ SHA256_SHR( 3,word))
-#define SHA256_sigma1(word) \
- (SHA256_ROTR(17,word) ^ SHA256_ROTR(19,word) ^ SHA256_SHR(10,word))
-
-/*
- * add "length" to the length
- */
-static uint32_t addTemp;
-#define SHA224_256AddLength(context, length) \
- (addTemp = (context)->Length_Low, (context)->Corrupted = \
- (((context)->Length_Low += (length)) < addTemp) && \
- (++(context)->Length_High == 0) ? 1 : 0)
-
-/* Local Function Prototypes */
-static void SHA224_256Finalize(SHA256Context *context,
- uint8_t Pad_Byte);
-static void SHA224_256PadMessage(SHA256Context *context,
- uint8_t Pad_Byte);
-static void SHA224_256ProcessMessageBlock(SHA256Context *context);
-static int SHA224_256Reset(SHA256Context *context, uint32_t *H0);
-static int SHA224_256ResultN(SHA256Context *context,
- uint8_t Message_Digest[], int HashSize);
-
-/* Initial Hash Values: FIPS-180-2 Change Notice 1 */
-static uint32_t SHA224_H0[SHA256HashSize/4] = {
- 0xC1059ED8, 0x367CD507, 0x3070DD17, 0xF70E5939,
- 0xFFC00B31, 0x68581511, 0x64F98FA7, 0xBEFA4FA4
-};
-
-/* Initial Hash Values: FIPS-180-2 section 5.3.2 */
-static uint32_t SHA256_H0[SHA256HashSize/4] = {
- 0x6A09E667, 0xBB67AE85, 0x3C6EF372, 0xA54FF53A,
- 0x510E527F, 0x9B05688C, 0x1F83D9AB, 0x5BE0CD19
-};
-
-
-
-
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-
-
-/*
- * SHA224Reset
- *
- * Description:
- * This function will initialize the SHA384Context in preparation
- * for computing a new SHA224 message digest.
- *
- * Parameters:
- * context: [in/out]
- * The context to reset.
- *
- * Returns:
- * sha Error Code.
- */
-int SHA224Reset(SHA224Context *context)
-{
- return SHA224_256Reset(context, SHA224_H0);
-}
-
-/*
- * SHA224Input
- *
- * Description:
- * This function accepts an array of octets as the next portion
- * of the message.
- *
- * Parameters:
- * context: [in/out]
- * The SHA context to update
- * message_array: [in]
- * An array of characters representing the next portion of
- * the message.
- * length: [in]
- * The length of the message in message_array
- *
- * Returns:
- * sha Error Code.
- *
- */
-int SHA224Input(SHA224Context *context, const uint8_t *message_array,
- unsigned int length)
-{
- return SHA256Input(context, message_array, length);
-}
-
-/*
- * SHA224FinalBits
- *
-
-
-
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-
-
- * Description:
- * This function will add in any final bits of the message.
- *
- * Parameters:
- * context: [in/out]
- * The SHA context to update
- * message_bits: [in]
- * The final bits of the message, in the upper portion of the
- * byte. (Use 0b###00000 instead of 0b00000### to input the
- * three bits ###.)
- * length: [in]
- * The number of bits in message_bits, between 1 and 7.
- *
- * Returns:
- * sha Error Code.
- */
-int SHA224FinalBits( SHA224Context *context,
- const uint8_t message_bits, unsigned int length)
-{
- return SHA256FinalBits(context, message_bits, length);
-}
-
-/*
- * SHA224Result
- *
- * Description:
- * This function will return the 224-bit message
- * digest into the Message_Digest array provided by the caller.
- * NOTE: The first octet of hash is stored in the 0th element,
- * the last octet of hash in the 28th element.
- *
- * Parameters:
- * context: [in/out]
- * The context to use to calculate the SHA hash.
- * Message_Digest: [out]
- * Where the digest is returned.
- *
- * Returns:
- * sha Error Code.
- */
-int SHA224Result(SHA224Context *context,
- uint8_t Message_Digest[SHA224HashSize])
-{
- return SHA224_256ResultN(context, Message_Digest, SHA224HashSize);
-}
-
-/*
- * SHA256Reset
-
-
-
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-
-
- *
- * Description:
- * This function will initialize the SHA256Context in preparation
- * for computing a new SHA256 message digest.
- *
- * Parameters:
- * context: [in/out]
- * The context to reset.
- *
- * Returns:
- * sha Error Code.
- */
-int SHA256Reset(SHA256Context *context)
-{
- return SHA224_256Reset(context, SHA256_H0);
-}
-
-/*
- * SHA256Input
- *
- * Description:
- * This function accepts an array of octets as the next portion
- * of the message.
- *
- * Parameters:
- * context: [in/out]
- * The SHA context to update
- * message_array: [in]
- * An array of characters representing the next portion of
- * the message.
- * length: [in]
- * The length of the message in message_array
- *
- * Returns:
- * sha Error Code.
- */
-int SHA256Input(SHA256Context *context, const uint8_t *message_array,
- unsigned int length)
-{
- if (!length)
- return shaSuccess;
-
- if (!context || !message_array)
- return shaNull;
-
- if (context->Computed) {
- context->Corrupted = shaStateError;
- return shaStateError;
-
-
-
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-
-
- }
-
- if (context->Corrupted)
- return context->Corrupted;
-
- while (length-- && !context->Corrupted) {
- context->Message_Block[context->Message_Block_Index++] =
- (*message_array & 0xFF);
-
- if (!SHA224_256AddLength(context, 8) &&
- (context->Message_Block_Index == SHA256_Message_Block_Size))
- SHA224_256ProcessMessageBlock(context);
-
- message_array++;
- }
-
- return shaSuccess;
-
-}
-
-/*
- * SHA256FinalBits
- *
- * Description:
- * This function will add in any final bits of the message.
- *
- * Parameters:
- * context: [in/out]
- * The SHA context to update
- * message_bits: [in]
- * The final bits of the message, in the upper portion of the
- * byte. (Use 0b###00000 instead of 0b00000### to input the
- * three bits ###.)
- * length: [in]
- * The number of bits in message_bits, between 1 and 7.
- *
- * Returns:
- * sha Error Code.
- */
-int SHA256FinalBits(SHA256Context *context,
- const uint8_t message_bits, unsigned int length)
-{
- uint8_t masks[8] = {
- /* 0 0b00000000 */ 0x00, /* 1 0b10000000 */ 0x80,
- /* 2 0b11000000 */ 0xC0, /* 3 0b11100000 */ 0xE0,
- /* 4 0b11110000 */ 0xF0, /* 5 0b11111000 */ 0xF8,
- /* 6 0b11111100 */ 0xFC, /* 7 0b11111110 */ 0xFE
- };
-
-
-
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-
-
- uint8_t markbit[8] = {
- /* 0 0b10000000 */ 0x80, /* 1 0b01000000 */ 0x40,
- /* 2 0b00100000 */ 0x20, /* 3 0b00010000 */ 0x10,
- /* 4 0b00001000 */ 0x08, /* 5 0b00000100 */ 0x04,
- /* 6 0b00000010 */ 0x02, /* 7 0b00000001 */ 0x01
- };
-
- if (!length)
- return shaSuccess;
-
- if (!context)
- return shaNull;
-
- if ((context->Computed) || (length >= 8) || (length == 0)) {
- context->Corrupted = shaStateError;
- return shaStateError;
- }
-
- if (context->Corrupted)
- return context->Corrupted;
-
- SHA224_256AddLength(context, length);
- SHA224_256Finalize(context, (uint8_t)
- ((message_bits & masks[length]) | markbit[length]));
-
- return shaSuccess;
-}
-
-/*
- * SHA256Result
- *
- * Description:
- * This function will return the 256-bit message
- * digest into the Message_Digest array provided by the caller.
- * NOTE: The first octet of hash is stored in the 0th element,
- * the last octet of hash in the 32nd element.
- *
- * Parameters:
- * context: [in/out]
- * The context to use to calculate the SHA hash.
- * Message_Digest: [out]
- * Where the digest is returned.
- *
- * Returns:
- * sha Error Code.
- */
-int SHA256Result(SHA256Context *context, uint8_t Message_Digest[])
-{
-
-
-
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-
-
- return SHA224_256ResultN(context, Message_Digest, SHA256HashSize);
-}
-
-/*
- * SHA224_256Finalize
- *
- * Description:
- * This helper function finishes off the digest calculations.
- *
- * Parameters:
- * context: [in/out]
- * The SHA context to update
- * Pad_Byte: [in]
- * The last byte to add to the digest before the 0-padding
- * and length. This will contain the last bits of the message
- * followed by another single bit. If the message was an
- * exact multiple of 8-bits long, Pad_Byte will be 0x80.
- *
- * Returns:
- * sha Error Code.
- */
-static void SHA224_256Finalize(SHA256Context *context,
- uint8_t Pad_Byte)
-{
- int i;
- SHA224_256PadMessage(context, Pad_Byte);
- /* message may be sensitive, so clear it out */
- for (i = 0; i < SHA256_Message_Block_Size; ++i)
- context->Message_Block[i] = 0;
- context->Length_Low = 0; /* and clear length */
- context->Length_High = 0;
- context->Computed = 1;
-}
-
-/*
- * SHA224_256PadMessage
- *
- * Description:
- * According to the standard, the message must be padded to an
- * even 512 bits. The first padding bit must be a '1'. The
- * last 64 bits represent the length of the original message.
- * All bits in between should be 0. This helper function will pad
- * the message according to those rules by filling the
- * Message_Block array accordingly. When it returns, it can be
- * assumed that the message digest has been computed.
- *
- * Parameters:
- * context: [in/out]
-
-
-
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-
-
- * The context to pad
- * Pad_Byte: [in]
- * The last byte to add to the digest before the 0-padding
- * and length. This will contain the last bits of the message
- * followed by another single bit. If the message was an
- * exact multiple of 8-bits long, Pad_Byte will be 0x80.
- *
- * Returns:
- * Nothing.
- */
-static void SHA224_256PadMessage(SHA256Context *context,
- uint8_t Pad_Byte)
-{
- /*
- * Check to see if the current message block is too small to hold
- * the initial padding bits and length. If so, we will pad the
- * block, process it, and then continue padding into a second
- * block.
- */
- if (context->Message_Block_Index >= (SHA256_Message_Block_Size-8)) {
- context->Message_Block[context->Message_Block_Index++] = Pad_Byte;
- while (context->Message_Block_Index < SHA256_Message_Block_Size)
- context->Message_Block[context->Message_Block_Index++] = 0;
- SHA224_256ProcessMessageBlock(context);
- } else
- context->Message_Block[context->Message_Block_Index++] = Pad_Byte;
-
- while (context->Message_Block_Index < (SHA256_Message_Block_Size-8))
- context->Message_Block[context->Message_Block_Index++] = 0;
-
- /*
- * Store the message length as the last 8 octets
- */
- context->Message_Block[56] = (uint8_t)(context->Length_High >> 24);
- context->Message_Block[57] = (uint8_t)(context->Length_High >> 16);
- context->Message_Block[58] = (uint8_t)(context->Length_High >> 8);
- context->Message_Block[59] = (uint8_t)(context->Length_High);
- context->Message_Block[60] = (uint8_t)(context->Length_Low >> 24);
- context->Message_Block[61] = (uint8_t)(context->Length_Low >> 16);
- context->Message_Block[62] = (uint8_t)(context->Length_Low >> 8);
- context->Message_Block[63] = (uint8_t)(context->Length_Low);
-
- SHA224_256ProcessMessageBlock(context);
-}
-
-/*
- * SHA224_256ProcessMessageBlock
- *
-
-
-
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-
-
- * Description:
- * This function will process the next 512 bits of the message
- * stored in the Message_Block array.
- *
- * Parameters:
- * context: [in/out]
- * The SHA context to update
- *
- * Returns:
- * Nothing.
- *
- * Comments:
- * Many of the variable names in this code, especially the
- * single character names, were used because those were the
- * names used in the publication.
- */
-static void SHA224_256ProcessMessageBlock(SHA256Context *context)
-{
- /* Constants defined in FIPS-180-2, section 4.2.2 */
- static const uint32_t K[64] = {
- 0x428a2f98, 0x71374491, 0xb5c0fbcf, 0xe9b5dba5, 0x3956c25b,
- 0x59f111f1, 0x923f82a4, 0xab1c5ed5, 0xd807aa98, 0x12835b01,
- 0x243185be, 0x550c7dc3, 0x72be5d74, 0x80deb1fe, 0x9bdc06a7,
- 0xc19bf174, 0xe49b69c1, 0xefbe4786, 0x0fc19dc6, 0x240ca1cc,
- 0x2de92c6f, 0x4a7484aa, 0x5cb0a9dc, 0x76f988da, 0x983e5152,
- 0xa831c66d, 0xb00327c8, 0xbf597fc7, 0xc6e00bf3, 0xd5a79147,
- 0x06ca6351, 0x14292967, 0x27b70a85, 0x2e1b2138, 0x4d2c6dfc,
- 0x53380d13, 0x650a7354, 0x766a0abb, 0x81c2c92e, 0x92722c85,
- 0xa2bfe8a1, 0xa81a664b, 0xc24b8b70, 0xc76c51a3, 0xd192e819,
- 0xd6990624, 0xf40e3585, 0x106aa070, 0x19a4c116, 0x1e376c08,
- 0x2748774c, 0x34b0bcb5, 0x391c0cb3, 0x4ed8aa4a, 0x5b9cca4f,
- 0x682e6ff3, 0x748f82ee, 0x78a5636f, 0x84c87814, 0x8cc70208,
- 0x90befffa, 0xa4506ceb, 0xbef9a3f7, 0xc67178f2
- };
- int t, t4; /* Loop counter */
- uint32_t temp1, temp2; /* Temporary word value */
- uint32_t W[64]; /* Word sequence */
- uint32_t A, B, C, D, E, F, G, H; /* Word buffers */
-
- /*
- * Initialize the first 16 words in the array W
- */
- for (t = t4 = 0; t < 16; t++, t4 += 4)
- W[t] = (((uint32_t)context->Message_Block[t4]) << 24) |
- (((uint32_t)context->Message_Block[t4 + 1]) << 16) |
- (((uint32_t)context->Message_Block[t4 + 2]) << 8) |
- (((uint32_t)context->Message_Block[t4 + 3]));
-
-
-
-
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-
-
- for (t = 16; t < 64; t++)
- W[t] = SHA256_sigma1(W[t-2]) + W[t-7] +
- SHA256_sigma0(W[t-15]) + W[t-16];
-
- A = context->Intermediate_Hash[0];
- B = context->Intermediate_Hash[1];
- C = context->Intermediate_Hash[2];
- D = context->Intermediate_Hash[3];
- E = context->Intermediate_Hash[4];
- F = context->Intermediate_Hash[5];
- G = context->Intermediate_Hash[6];
- H = context->Intermediate_Hash[7];
-
- for (t = 0; t < 64; t++) {
- temp1 = H + SHA256_SIGMA1(E) + SHA_Ch(E,F,G) + K[t] + W[t];
- temp2 = SHA256_SIGMA0(A) + SHA_Maj(A,B,C);
- H = G;
- G = F;
- F = E;
- E = D + temp1;
- D = C;
- C = B;
- B = A;
- A = temp1 + temp2;
- }
-
- context->Intermediate_Hash[0] += A;
- context->Intermediate_Hash[1] += B;
- context->Intermediate_Hash[2] += C;
- context->Intermediate_Hash[3] += D;
- context->Intermediate_Hash[4] += E;
- context->Intermediate_Hash[5] += F;
- context->Intermediate_Hash[6] += G;
- context->Intermediate_Hash[7] += H;
-
- context->Message_Block_Index = 0;
-}
-
-/*
- * SHA224_256Reset
- *
- * Description:
- * This helper function will initialize the SHA256Context in
- * preparation for computing a new SHA256 message digest.
- *
- * Parameters:
- * context: [in/out]
- * The context to reset.
-
-
-
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-
-
- * H0
- * The initial hash value to use.
- *
- * Returns:
- * sha Error Code.
- */
-static int SHA224_256Reset(SHA256Context *context, uint32_t *H0)
-{
- if (!context)
- return shaNull;
-
- context->Length_Low = 0;
- context->Length_High = 0;
- context->Message_Block_Index = 0;
-
- context->Intermediate_Hash[0] = H0[0];
- context->Intermediate_Hash[1] = H0[1];
- context->Intermediate_Hash[2] = H0[2];
- context->Intermediate_Hash[3] = H0[3];
- context->Intermediate_Hash[4] = H0[4];
- context->Intermediate_Hash[5] = H0[5];
- context->Intermediate_Hash[6] = H0[6];
- context->Intermediate_Hash[7] = H0[7];
-
- context->Computed = 0;
- context->Corrupted = 0;
-
- return shaSuccess;
-}
-
-/*
- * SHA224_256ResultN
- *
- * Description:
- * This helper function will return the 224-bit or 256-bit message
- * digest into the Message_Digest array provided by the caller.
- * NOTE: The first octet of hash is stored in the 0th element,
- * the last octet of hash in the 28th/32nd element.
- *
- * Parameters:
- * context: [in/out]
- * The context to use to calculate the SHA hash.
- * Message_Digest: [out]
- * Where the digest is returned.
- * HashSize: [in]
- * The size of the hash, either 28 or 32.
- *
- * Returns:
-
-
-
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-
-
- * sha Error Code.
- */
-static int SHA224_256ResultN(SHA256Context *context,
- uint8_t Message_Digest[], int HashSize)
-{
- int i;
-
- if (!context || !Message_Digest)
- return shaNull;
-
- if (context->Corrupted)
- return context->Corrupted;
-
- if (!context->Computed)
- SHA224_256Finalize(context, 0x80);
-
- for (i = 0; i < HashSize; ++i)
- Message_Digest[i] = (uint8_t)
- (context->Intermediate_Hash[i>>2] >> 8 * ( 3 - ( i & 0x03 ) ));
-
- return shaSuccess;
-}
-
-8.2.3. sha384-512.c
-
-/*************************** sha384-512.c ***************************/
-/********************* See RFC 4634 for details *********************/
-/*
- * Description:
- * This file implements the Secure Hash Signature Standard
- * algorithms as defined in the National Institute of Standards
- * and Technology Federal Information Processing Standards
- * Publication (FIPS PUB) 180-1 published on April 17, 1995, 180-2
- * published on August 1, 2002, and the FIPS PUB 180-2 Change
- * Notice published on February 28, 2004.
- *
- * A combined document showing all algorithms is available at
- * http://csrc.nist.gov/publications/fips/
- * fips180-2/fips180-2withchangenotice.pdf
- *
- * The SHA-384 and SHA-512 algorithms produce 384-bit and 512-bit
- * message digests for a given data stream. It should take about
- * 2**n steps to find a message with the same digest as a given
- * message and 2**(n/2) to find any two messages with the same
- * digest, when n is the digest size in bits. Therefore, this
- * algorithm can serve as a means of providing a
- * "fingerprint" for a message.
- *
-
-
-
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-
-
- * Portability Issues:
- * SHA-384 and SHA-512 are defined in terms of 64-bit "words",
- * but if USE_32BIT_ONLY is #defined, this code is implemented in
- * terms of 32-bit "words". This code uses <stdint.h> (included
- * via "sha.h") to define the 64, 32 and 8 bit unsigned integer
- * types. If your C compiler does not support 64 bit unsigned
- * integers, and you do not #define USE_32BIT_ONLY, this code is
- * not appropriate.
- *
- * Caveats:
- * SHA-384 and SHA-512 are designed to work with messages less
- * than 2^128 bits long. This implementation uses
- * SHA384/512Input() to hash the bits that are a multiple of the
- * size of an 8-bit character, and then uses SHA384/256FinalBits()
- * to hash the final few bits of the input.
- *
- */
-
-#include "sha.h"
-#include "sha-private.h"
-
-#ifdef USE_32BIT_ONLY
-/*
- * Define 64-bit arithmetic in terms of 32-bit arithmetic.
- * Each 64-bit number is represented in a 2-word array.
- * All macros are defined such that the result is the last parameter.
- */
-
-/*
- * Define shift, rotate left and rotate right functions
- */
-#define SHA512_SHR(bits, word, ret) ( \
- /* (((uint64_t)((word))) >> (bits)) */ \
- (ret)[0] = (((bits) < 32) && ((bits) >= 0)) ? \
- ((word)[0] >> (bits)) : 0, \
- (ret)[1] = ((bits) > 32) ? ((word)[0] >> ((bits) - 32)) : \
- ((bits) == 32) ? (word)[0] : \
- ((bits) >= 0) ? \
- (((word)[0] << (32 - (bits))) | \
- ((word)[1] >> (bits))) : 0 )
-
-#define SHA512_SHL(bits, word, ret) ( \
- /* (((uint64_t)(word)) << (bits)) */ \
- (ret)[0] = ((bits) > 32) ? ((word)[1] << ((bits) - 32)) : \
- ((bits) == 32) ? (word)[1] : \
- ((bits) >= 0) ? \
- (((word)[0] << (bits)) | \
- ((word)[1] >> (32 - (bits)))) : \
-
-
-
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-
-
- 0, \
- (ret)[1] = (((bits) < 32) && ((bits) >= 0)) ? \
- ((word)[1] << (bits)) : 0 )
-
-/*
- * Define 64-bit OR
- */
-#define SHA512_OR(word1, word2, ret) ( \
- (ret)[0] = (word1)[0] | (word2)[0], \
- (ret)[1] = (word1)[1] | (word2)[1] )
-
-/*
- * Define 64-bit XOR
- */
-#define SHA512_XOR(word1, word2, ret) ( \
- (ret)[0] = (word1)[0] ^ (word2)[0], \
- (ret)[1] = (word1)[1] ^ (word2)[1] )
-
-/*
- * Define 64-bit AND
- */
-#define SHA512_AND(word1, word2, ret) ( \
- (ret)[0] = (word1)[0] & (word2)[0], \
- (ret)[1] = (word1)[1] & (word2)[1] )
-
-/*
- * Define 64-bit TILDA
- */
-#define SHA512_TILDA(word, ret) \
- ( (ret)[0] = ~(word)[0], (ret)[1] = ~(word)[1] )
-
-/*
- * Define 64-bit ADD
- */
-#define SHA512_ADD(word1, word2, ret) ( \
- (ret)[1] = (word1)[1], (ret)[1] += (word2)[1], \
- (ret)[0] = (word1)[0] + (word2)[0] + ((ret)[1] < (word1)[1]) )
-
-/*
- * Add the 4word value in word2 to word1.
- */
-static uint32_t ADDTO4_temp, ADDTO4_temp2;
-#define SHA512_ADDTO4(word1, word2) ( \
- ADDTO4_temp = (word1)[3], \
- (word1)[3] += (word2)[3], \
- ADDTO4_temp2 = (word1)[2], \
- (word1)[2] += (word2)[2] + ((word1)[3] < ADDTO4_temp), \
- ADDTO4_temp = (word1)[1], \
-
-
-
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-
-
- (word1)[1] += (word2)[1] + ((word1)[2] < ADDTO4_temp2), \
- (word1)[0] += (word2)[0] + ((word1)[1] < ADDTO4_temp) )
-
-/*
- * Add the 2word value in word2 to word1.
- */
-static uint32_t ADDTO2_temp;
-#define SHA512_ADDTO2(word1, word2) ( \
- ADDTO2_temp = (word1)[1], \
- (word1)[1] += (word2)[1], \
- (word1)[0] += (word2)[0] + ((word1)[1] < ADDTO2_temp) )
-
-/*
- * SHA rotate ((word >> bits) | (word << (64-bits)))
- */
-static uint32_t ROTR_temp1[2], ROTR_temp2[2];
-#define SHA512_ROTR(bits, word, ret) ( \
- SHA512_SHR((bits), (word), ROTR_temp1), \
- SHA512_SHL(64-(bits), (word), ROTR_temp2), \
- SHA512_OR(ROTR_temp1, ROTR_temp2, (ret)) )
-
-/*
- * Define the SHA SIGMA and sigma macros
- * SHA512_ROTR(28,word) ^ SHA512_ROTR(34,word) ^ SHA512_ROTR(39,word)
- */
-static uint32_t SIGMA0_temp1[2], SIGMA0_temp2[2],
- SIGMA0_temp3[2], SIGMA0_temp4[2];
-#define SHA512_SIGMA0(word, ret) ( \
- SHA512_ROTR(28, (word), SIGMA0_temp1), \
- SHA512_ROTR(34, (word), SIGMA0_temp2), \
- SHA512_ROTR(39, (word), SIGMA0_temp3), \
- SHA512_XOR(SIGMA0_temp2, SIGMA0_temp3, SIGMA0_temp4), \
- SHA512_XOR(SIGMA0_temp1, SIGMA0_temp4, (ret)) )
-
-/*
- * SHA512_ROTR(14,word) ^ SHA512_ROTR(18,word) ^ SHA512_ROTR(41,word)
- */
-static uint32_t SIGMA1_temp1[2], SIGMA1_temp2[2],
- SIGMA1_temp3[2], SIGMA1_temp4[2];
-#define SHA512_SIGMA1(word, ret) ( \
- SHA512_ROTR(14, (word), SIGMA1_temp1), \
- SHA512_ROTR(18, (word), SIGMA1_temp2), \
- SHA512_ROTR(41, (word), SIGMA1_temp3), \
- SHA512_XOR(SIGMA1_temp2, SIGMA1_temp3, SIGMA1_temp4), \
- SHA512_XOR(SIGMA1_temp1, SIGMA1_temp4, (ret)) )
-
-/*
- * (SHA512_ROTR( 1,word) ^ SHA512_ROTR( 8,word) ^ SHA512_SHR( 7,word))
-
-
-
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-
-
- */
-static uint32_t sigma0_temp1[2], sigma0_temp2[2],
- sigma0_temp3[2], sigma0_temp4[2];
-#define SHA512_sigma0(word, ret) ( \
- SHA512_ROTR( 1, (word), sigma0_temp1), \
- SHA512_ROTR( 8, (word), sigma0_temp2), \
- SHA512_SHR( 7, (word), sigma0_temp3), \
- SHA512_XOR(sigma0_temp2, sigma0_temp3, sigma0_temp4), \
- SHA512_XOR(sigma0_temp1, sigma0_temp4, (ret)) )
-
-/*
- * (SHA512_ROTR(19,word) ^ SHA512_ROTR(61,word) ^ SHA512_SHR( 6,word))
- */
-static uint32_t sigma1_temp1[2], sigma1_temp2[2],
- sigma1_temp3[2], sigma1_temp4[2];
-#define SHA512_sigma1(word, ret) ( \
- SHA512_ROTR(19, (word), sigma1_temp1), \
- SHA512_ROTR(61, (word), sigma1_temp2), \
- SHA512_SHR( 6, (word), sigma1_temp3), \
- SHA512_XOR(sigma1_temp2, sigma1_temp3, sigma1_temp4), \
- SHA512_XOR(sigma1_temp1, sigma1_temp4, (ret)) )
-
-#undef SHA_Ch
-#undef SHA_Maj
-
-#ifndef USE_MODIFIED_MACROS
-/*
- * These definitions are the ones used in FIPS-180-2, section 4.1.3
- * Ch(x,y,z) ((x & y) ^ (~x & z))
- */
-static uint32_t Ch_temp1[2], Ch_temp2[2], Ch_temp3[2];
-#define SHA_Ch(x, y, z, ret) ( \
- SHA512_AND(x, y, Ch_temp1), \
- SHA512_TILDA(x, Ch_temp2), \
- SHA512_AND(Ch_temp2, z, Ch_temp3), \
- SHA512_XOR(Ch_temp1, Ch_temp3, (ret)) )
-/*
- * Maj(x,y,z) (((x)&(y)) ^ ((x)&(z)) ^ ((y)&(z)))
- */
-static uint32_t Maj_temp1[2], Maj_temp2[2],
- Maj_temp3[2], Maj_temp4[2];
-#define SHA_Maj(x, y, z, ret) ( \
- SHA512_AND(x, y, Maj_temp1), \
- SHA512_AND(x, z, Maj_temp2), \
- SHA512_AND(y, z, Maj_temp3), \
- SHA512_XOR(Maj_temp2, Maj_temp3, Maj_temp4), \
- SHA512_XOR(Maj_temp1, Maj_temp4, (ret)) )
-
-
-
-
-Eastlake 3rd & Hansen Informational [Page 49]
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-
-
-#else /* !USE_32BIT_ONLY */
-/*
- * These definitions are potentially faster equivalents for the ones
- * used in FIPS-180-2, section 4.1.3.
- * ((x & y) ^ (~x & z)) becomes
- * ((x & (y ^ z)) ^ z)
- */
-#define SHA_Ch(x, y, z, ret) ( \
- (ret)[0] = (((x)[0] & ((y)[0] ^ (z)[0])) ^ (z)[0]), \
- (ret)[1] = (((x)[1] & ((y)[1] ^ (z)[1])) ^ (z)[1]) )
-
-/*
- * ((x & y) ^ (x & z) ^ (y & z)) becomes
- * ((x & (y | z)) | (y & z))
- */
-#define SHA_Maj(x, y, z, ret) ( \
- ret[0] = (((x)[0] & ((y)[0] | (z)[0])) | ((y)[0] & (z)[0])), \
- ret[1] = (((x)[1] & ((y)[1] | (z)[1])) | ((y)[1] & (z)[1])) )
-#endif /* USE_MODIFIED_MACROS */
-
-/*
- * add "length" to the length
- */
-static uint32_t addTemp[4] = { 0, 0, 0, 0 };
-#define SHA384_512AddLength(context, length) ( \
- addTemp[3] = (length), SHA512_ADDTO4((context)->Length, addTemp), \
- (context)->Corrupted = (((context)->Length[3] == 0) && \
- ((context)->Length[2] == 0) && ((context)->Length[1] == 0) && \
- ((context)->Length[0] < 8)) ? 1 : 0 )
-
-/* Local Function Prototypes */
-static void SHA384_512Finalize(SHA512Context *context,
- uint8_t Pad_Byte);
-static void SHA384_512PadMessage(SHA512Context *context,
- uint8_t Pad_Byte);
-static void SHA384_512ProcessMessageBlock(SHA512Context *context);
-static int SHA384_512Reset(SHA512Context *context, uint32_t H0[]);
-static int SHA384_512ResultN( SHA512Context *context,
- uint8_t Message_Digest[], int HashSize);
-
-/* Initial Hash Values: FIPS-180-2 sections 5.3.3 and 5.3.4 */
-static uint32_t SHA384_H0[SHA512HashSize/4] = {
- 0xCBBB9D5D, 0xC1059ED8, 0x629A292A, 0x367CD507, 0x9159015A,
- 0x3070DD17, 0x152FECD8, 0xF70E5939, 0x67332667, 0xFFC00B31,
- 0x8EB44A87, 0x68581511, 0xDB0C2E0D, 0x64F98FA7, 0x47B5481D,
- 0xBEFA4FA4
-};
-
-
-
-
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-
-
-static uint32_t SHA512_H0[SHA512HashSize/4] = {
- 0x6A09E667, 0xF3BCC908, 0xBB67AE85, 0x84CAA73B, 0x3C6EF372,
- 0xFE94F82B, 0xA54FF53A, 0x5F1D36F1, 0x510E527F, 0xADE682D1,
- 0x9B05688C, 0x2B3E6C1F, 0x1F83D9AB, 0xFB41BD6B, 0x5BE0CD19,
- 0x137E2179
-};
-
-#else /* !USE_32BIT_ONLY */
-
-/* Define the SHA shift, rotate left and rotate right macro */
-#define SHA512_SHR(bits,word) (((uint64_t)(word)) >> (bits))
-#define SHA512_ROTR(bits,word) ((((uint64_t)(word)) >> (bits)) | \
- (((uint64_t)(word)) << (64-(bits))))
-
-/* Define the SHA SIGMA and sigma macros */
-#define SHA512_SIGMA0(word) \
- (SHA512_ROTR(28,word) ^ SHA512_ROTR(34,word) ^ SHA512_ROTR(39,word))
-#define SHA512_SIGMA1(word) \
- (SHA512_ROTR(14,word) ^ SHA512_ROTR(18,word) ^ SHA512_ROTR(41,word))
-#define SHA512_sigma0(word) \
- (SHA512_ROTR( 1,word) ^ SHA512_ROTR( 8,word) ^ SHA512_SHR( 7,word))
-#define SHA512_sigma1(word) \
- (SHA512_ROTR(19,word) ^ SHA512_ROTR(61,word) ^ SHA512_SHR( 6,word))
-
-/*
- * add "length" to the length
- */
-static uint64_t addTemp;
-#define SHA384_512AddLength(context, length) \
- (addTemp = context->Length_Low, context->Corrupted = \
- ((context->Length_Low += length) < addTemp) && \
- (++context->Length_High == 0) ? 1 : 0)
-
-/* Local Function Prototypes */
-static void SHA384_512Finalize(SHA512Context *context,
- uint8_t Pad_Byte);
-static void SHA384_512PadMessage(SHA512Context *context,
- uint8_t Pad_Byte);
-static void SHA384_512ProcessMessageBlock(SHA512Context *context);
-static int SHA384_512Reset(SHA512Context *context, uint64_t H0[]);
-static int SHA384_512ResultN(SHA512Context *context,
- uint8_t Message_Digest[], int HashSize);
-
-/* Initial Hash Values: FIPS-180-2 sections 5.3.3 and 5.3.4 */
-static uint64_t SHA384_H0[] = {
- 0xCBBB9D5DC1059ED8ll, 0x629A292A367CD507ll, 0x9159015A3070DD17ll,
- 0x152FECD8F70E5939ll, 0x67332667FFC00B31ll, 0x8EB44A8768581511ll,
- 0xDB0C2E0D64F98FA7ll, 0x47B5481DBEFA4FA4ll
-
-
-
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-
-
-};
-static uint64_t SHA512_H0[] = {
- 0x6A09E667F3BCC908ll, 0xBB67AE8584CAA73Bll, 0x3C6EF372FE94F82Bll,
- 0xA54FF53A5F1D36F1ll, 0x510E527FADE682D1ll, 0x9B05688C2B3E6C1Fll,
- 0x1F83D9ABFB41BD6Bll, 0x5BE0CD19137E2179ll
-};
-
-#endif /* USE_32BIT_ONLY */
-
-/*
- * SHA384Reset
- *
- * Description:
- * This function will initialize the SHA384Context in preparation
- * for computing a new SHA384 message digest.
- *
- * Parameters:
- * context: [in/out]
- * The context to reset.
- *
- * Returns:
- * sha Error Code.
- *
- */
-int SHA384Reset(SHA384Context *context)
-{
- return SHA384_512Reset(context, SHA384_H0);
-}
-
-/*
- * SHA384Input
- *
- * Description:
- * This function accepts an array of octets as the next portion
- * of the message.
- *
- * Parameters:
- * context: [in/out]
- * The SHA context to update
- * message_array: [in]
- * An array of characters representing the next portion of
- * the message.
- * length: [in]
- * The length of the message in message_array
- *
- * Returns:
- * sha Error Code.
- *
-
-
-
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-
-
- */
-int SHA384Input(SHA384Context *context,
- const uint8_t *message_array, unsigned int length)
-{
- return SHA512Input(context, message_array, length);
-}
-
-/*
- * SHA384FinalBits
- *
- * Description:
- * This function will add in any final bits of the message.
- *
- * Parameters:
- * context: [in/out]
- * The SHA context to update
- * message_bits: [in]
- * The final bits of the message, in the upper portion of the
- * byte. (Use 0b###00000 instead of 0b00000### to input the
- * three bits ###.)
- * length: [in]
- * The number of bits in message_bits, between 1 and 7.
- *
- * Returns:
- * sha Error Code.
- *
- */
-int SHA384FinalBits(SHA384Context *context,
- const uint8_t message_bits, unsigned int length)
-{
- return SHA512FinalBits(context, message_bits, length);
-}
-
-/*
- * SHA384Result
- *
- * Description:
- * This function will return the 384-bit message
- * digest into the Message_Digest array provided by the caller.
- * NOTE: The first octet of hash is stored in the 0th element,
- * the last octet of hash in the 48th element.
- *
- * Parameters:
- * context: [in/out]
- * The context to use to calculate the SHA hash.
- * Message_Digest: [out]
- * Where the digest is returned.
- *
-
-
-
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-
-
- * Returns:
- * sha Error Code.
- *
- */
-int SHA384Result(SHA384Context *context,
- uint8_t Message_Digest[SHA384HashSize])
-{
- return SHA384_512ResultN(context, Message_Digest, SHA384HashSize);
-}
-
-/*
- * SHA512Reset
- *
- * Description:
- * This function will initialize the SHA512Context in preparation
- * for computing a new SHA512 message digest.
- *
- * Parameters:
- * context: [in/out]
- * The context to reset.
- *
- * Returns:
- * sha Error Code.
- *
- */
-int SHA512Reset(SHA512Context *context)
-{
- return SHA384_512Reset(context, SHA512_H0);
-}
-
-/*
- * SHA512Input
- *
- * Description:
- * This function accepts an array of octets as the next portion
- * of the message.
- *
- * Parameters:
- * context: [in/out]
- * The SHA context to update
- * message_array: [in]
- * An array of characters representing the next portion of
- * the message.
- * length: [in]
- * The length of the message in message_array
- *
- * Returns:
- * sha Error Code.
-
-
-
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-
-
- *
- */
-int SHA512Input(SHA512Context *context,
- const uint8_t *message_array,
- unsigned int length)
-{
- if (!length)
- return shaSuccess;
-
- if (!context || !message_array)
- return shaNull;
-
- if (context->Computed) {
- context->Corrupted = shaStateError;
- return shaStateError;
- }
-
- if (context->Corrupted)
- return context->Corrupted;
-
- while (length-- && !context->Corrupted) {
- context->Message_Block[context->Message_Block_Index++] =
- (*message_array & 0xFF);
-
- if (!SHA384_512AddLength(context, 8) &&
- (context->Message_Block_Index == SHA512_Message_Block_Size))
- SHA384_512ProcessMessageBlock(context);
-
- message_array++;
- }
-
- return shaSuccess;
-}
-
-/*
- * SHA512FinalBits
- *
- * Description:
- * This function will add in any final bits of the message.
- *
- * Parameters:
- * context: [in/out]
- * The SHA context to update
- * message_bits: [in]
- * The final bits of the message, in the upper portion of the
- * byte. (Use 0b###00000 instead of 0b00000### to input the
- * three bits ###.)
- * length: [in]
-
-
-
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-
-
- * The number of bits in message_bits, between 1 and 7.
- *
- * Returns:
- * sha Error Code.
- *
- */
-int SHA512FinalBits(SHA512Context *context,
- const uint8_t message_bits, unsigned int length)
-{
- uint8_t masks[8] = {
- /* 0 0b00000000 */ 0x00, /* 1 0b10000000 */ 0x80,
- /* 2 0b11000000 */ 0xC0, /* 3 0b11100000 */ 0xE0,
- /* 4 0b11110000 */ 0xF0, /* 5 0b11111000 */ 0xF8,
- /* 6 0b11111100 */ 0xFC, /* 7 0b11111110 */ 0xFE
- };
- uint8_t markbit[8] = {
- /* 0 0b10000000 */ 0x80, /* 1 0b01000000 */ 0x40,
- /* 2 0b00100000 */ 0x20, /* 3 0b00010000 */ 0x10,
- /* 4 0b00001000 */ 0x08, /* 5 0b00000100 */ 0x04,
- /* 6 0b00000010 */ 0x02, /* 7 0b00000001 */ 0x01
- };
-
- if (!length)
- return shaSuccess;
-
- if (!context)
- return shaNull;
-
- if ((context->Computed) || (length >= 8) || (length == 0)) {
- context->Corrupted = shaStateError;
- return shaStateError;
- }
-
- if (context->Corrupted)
- return context->Corrupted;
-
- SHA384_512AddLength(context, length);
- SHA384_512Finalize(context, (uint8_t)
- ((message_bits & masks[length]) | markbit[length]));
-
- return shaSuccess;
-}
-
-/*
- * SHA384_512Finalize
- *
- * Description:
- * This helper function finishes off the digest calculations.
-
-
-
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-
-
- *
- * Parameters:
- * context: [in/out]
- * The SHA context to update
- * Pad_Byte: [in]
- * The last byte to add to the digest before the 0-padding
- * and length. This will contain the last bits of the message
- * followed by another single bit. If the message was an
- * exact multiple of 8-bits long, Pad_Byte will be 0x80.
- *
- * Returns:
- * sha Error Code.
- *
- */
-static void SHA384_512Finalize(SHA512Context *context,
- uint8_t Pad_Byte)
-{
- int_least16_t i;
- SHA384_512PadMessage(context, Pad_Byte);
- /* message may be sensitive, clear it out */
- for (i = 0; i < SHA512_Message_Block_Size; ++i)
- context->Message_Block[i] = 0;
-#ifdef USE_32BIT_ONLY /* and clear length */
- context->Length[0] = context->Length[1] = 0;
- context->Length[2] = context->Length[3] = 0;
-#else /* !USE_32BIT_ONLY */
- context->Length_Low = 0;
- context->Length_High = 0;
-#endif /* USE_32BIT_ONLY */
- context->Computed = 1;
-}
-
-/*
- * SHA512Result
- *
- * Description:
- * This function will return the 512-bit message
- * digest into the Message_Digest array provided by the caller.
- * NOTE: The first octet of hash is stored in the 0th element,
- * the last octet of hash in the 64th element.
- *
- * Parameters:
- * context: [in/out]
- * The context to use to calculate the SHA hash.
- * Message_Digest: [out]
- * Where the digest is returned.
- *
- * Returns:
-
-
-
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-
-
- * sha Error Code.
- *
- */
-int SHA512Result(SHA512Context *context,
- uint8_t Message_Digest[SHA512HashSize])
-{
- return SHA384_512ResultN(context, Message_Digest, SHA512HashSize);
-}
-
-/*
- * SHA384_512PadMessage
- *
- * Description:
- * According to the standard, the message must be padded to an
- * even 1024 bits. The first padding bit must be a '1'. The
- * last 128 bits represent the length of the original message.
- * All bits in between should be 0. This helper function will
- * pad the message according to those rules by filling the
- * Message_Block array accordingly. When it returns, it can be
- * assumed that the message digest has been computed.
- *
- * Parameters:
- * context: [in/out]
- * The context to pad
- * Pad_Byte: [in]
- * The last byte to add to the digest before the 0-padding
- * and length. This will contain the last bits of the message
- * followed by another single bit. If the message was an
- * exact multiple of 8-bits long, Pad_Byte will be 0x80.
- *
- * Returns:
- * Nothing.
- *
- */
-static void SHA384_512PadMessage(SHA512Context *context,
- uint8_t Pad_Byte)
-{
- /*
- * Check to see if the current message block is too small to hold
- * the initial padding bits and length. If so, we will pad the
- * block, process it, and then continue padding into a second
- * block.
- */
- if (context->Message_Block_Index >= (SHA512_Message_Block_Size-16)) {
- context->Message_Block[context->Message_Block_Index++] = Pad_Byte;
- while (context->Message_Block_Index < SHA512_Message_Block_Size)
- context->Message_Block[context->Message_Block_Index++] = 0;
-
-
-
-
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-
-
- SHA384_512ProcessMessageBlock(context);
- } else
- context->Message_Block[context->Message_Block_Index++] = Pad_Byte;
-
- while (context->Message_Block_Index < (SHA512_Message_Block_Size-16))
- context->Message_Block[context->Message_Block_Index++] = 0;
-
- /*
- * Store the message length as the last 16 octets
- */
-#ifdef USE_32BIT_ONLY
- context->Message_Block[112] = (uint8_t)(context->Length[0] >> 24);
- context->Message_Block[113] = (uint8_t)(context->Length[0] >> 16);
- context->Message_Block[114] = (uint8_t)(context->Length[0] >> 8);
- context->Message_Block[115] = (uint8_t)(context->Length[0]);
- context->Message_Block[116] = (uint8_t)(context->Length[1] >> 24);
- context->Message_Block[117] = (uint8_t)(context->Length[1] >> 16);
- context->Message_Block[118] = (uint8_t)(context->Length[1] >> 8);
- context->Message_Block[119] = (uint8_t)(context->Length[1]);
-
- context->Message_Block[120] = (uint8_t)(context->Length[2] >> 24);
- context->Message_Block[121] = (uint8_t)(context->Length[2] >> 16);
- context->Message_Block[122] = (uint8_t)(context->Length[2] >> 8);
- context->Message_Block[123] = (uint8_t)(context->Length[2]);
- context->Message_Block[124] = (uint8_t)(context->Length[3] >> 24);
- context->Message_Block[125] = (uint8_t)(context->Length[3] >> 16);
- context->Message_Block[126] = (uint8_t)(context->Length[3] >> 8);
- context->Message_Block[127] = (uint8_t)(context->Length[3]);
-#else /* !USE_32BIT_ONLY */
- context->Message_Block[112] = (uint8_t)(context->Length_High >> 56);
- context->Message_Block[113] = (uint8_t)(context->Length_High >> 48);
- context->Message_Block[114] = (uint8_t)(context->Length_High >> 40);
- context->Message_Block[115] = (uint8_t)(context->Length_High >> 32);
- context->Message_Block[116] = (uint8_t)(context->Length_High >> 24);
- context->Message_Block[117] = (uint8_t)(context->Length_High >> 16);
- context->Message_Block[118] = (uint8_t)(context->Length_High >> 8);
- context->Message_Block[119] = (uint8_t)(context->Length_High);
-
- context->Message_Block[120] = (uint8_t)(context->Length_Low >> 56);
- context->Message_Block[121] = (uint8_t)(context->Length_Low >> 48);
- context->Message_Block[122] = (uint8_t)(context->Length_Low >> 40);
- context->Message_Block[123] = (uint8_t)(context->Length_Low >> 32);
- context->Message_Block[124] = (uint8_t)(context->Length_Low >> 24);
- context->Message_Block[125] = (uint8_t)(context->Length_Low >> 16);
- context->Message_Block[126] = (uint8_t)(context->Length_Low >> 8);
- context->Message_Block[127] = (uint8_t)(context->Length_Low);
-#endif /* USE_32BIT_ONLY */
-
-
-
-
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-
-
- SHA384_512ProcessMessageBlock(context);
-}
-
-/*
- * SHA384_512ProcessMessageBlock
- *
- * Description:
- * This helper function will process the next 1024 bits of the
- * message stored in the Message_Block array.
- *
- * Parameters:
- * context: [in/out]
- * The SHA context to update
- *
- * Returns:
- * Nothing.
- *
- * Comments:
- * Many of the variable names in this code, especially the
- * single character names, were used because those were the
- * names used in the publication.
- *
- *
- */
-static void SHA384_512ProcessMessageBlock(SHA512Context *context)
-{
- /* Constants defined in FIPS-180-2, section 4.2.3 */
-#ifdef USE_32BIT_ONLY
- static const uint32_t K[80*2] = {
- 0x428A2F98, 0xD728AE22, 0x71374491, 0x23EF65CD, 0xB5C0FBCF,
- 0xEC4D3B2F, 0xE9B5DBA5, 0x8189DBBC, 0x3956C25B, 0xF348B538,
- 0x59F111F1, 0xB605D019, 0x923F82A4, 0xAF194F9B, 0xAB1C5ED5,
- 0xDA6D8118, 0xD807AA98, 0xA3030242, 0x12835B01, 0x45706FBE,
- 0x243185BE, 0x4EE4B28C, 0x550C7DC3, 0xD5FFB4E2, 0x72BE5D74,
- 0xF27B896F, 0x80DEB1FE, 0x3B1696B1, 0x9BDC06A7, 0x25C71235,
- 0xC19BF174, 0xCF692694, 0xE49B69C1, 0x9EF14AD2, 0xEFBE4786,
- 0x384F25E3, 0x0FC19DC6, 0x8B8CD5B5, 0x240CA1CC, 0x77AC9C65,
- 0x2DE92C6F, 0x592B0275, 0x4A7484AA, 0x6EA6E483, 0x5CB0A9DC,
- 0xBD41FBD4, 0x76F988DA, 0x831153B5, 0x983E5152, 0xEE66DFAB,
- 0xA831C66D, 0x2DB43210, 0xB00327C8, 0x98FB213F, 0xBF597FC7,
- 0xBEEF0EE4, 0xC6E00BF3, 0x3DA88FC2, 0xD5A79147, 0x930AA725,
- 0x06CA6351, 0xE003826F, 0x14292967, 0x0A0E6E70, 0x27B70A85,
- 0x46D22FFC, 0x2E1B2138, 0x5C26C926, 0x4D2C6DFC, 0x5AC42AED,
- 0x53380D13, 0x9D95B3DF, 0x650A7354, 0x8BAF63DE, 0x766A0ABB,
- 0x3C77B2A8, 0x81C2C92E, 0x47EDAEE6, 0x92722C85, 0x1482353B,
- 0xA2BFE8A1, 0x4CF10364, 0xA81A664B, 0xBC423001, 0xC24B8B70,
- 0xD0F89791, 0xC76C51A3, 0x0654BE30, 0xD192E819, 0xD6EF5218,
- 0xD6990624, 0x5565A910, 0xF40E3585, 0x5771202A, 0x106AA070,
-
-
-
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-
-
- 0x32BBD1B8, 0x19A4C116, 0xB8D2D0C8, 0x1E376C08, 0x5141AB53,
- 0x2748774C, 0xDF8EEB99, 0x34B0BCB5, 0xE19B48A8, 0x391C0CB3,
- 0xC5C95A63, 0x4ED8AA4A, 0xE3418ACB, 0x5B9CCA4F, 0x7763E373,
- 0x682E6FF3, 0xD6B2B8A3, 0x748F82EE, 0x5DEFB2FC, 0x78A5636F,
- 0x43172F60, 0x84C87814, 0xA1F0AB72, 0x8CC70208, 0x1A6439EC,
- 0x90BEFFFA, 0x23631E28, 0xA4506CEB, 0xDE82BDE9, 0xBEF9A3F7,
- 0xB2C67915, 0xC67178F2, 0xE372532B, 0xCA273ECE, 0xEA26619C,
- 0xD186B8C7, 0x21C0C207, 0xEADA7DD6, 0xCDE0EB1E, 0xF57D4F7F,
- 0xEE6ED178, 0x06F067AA, 0x72176FBA, 0x0A637DC5, 0xA2C898A6,
- 0x113F9804, 0xBEF90DAE, 0x1B710B35, 0x131C471B, 0x28DB77F5,
- 0x23047D84, 0x32CAAB7B, 0x40C72493, 0x3C9EBE0A, 0x15C9BEBC,
- 0x431D67C4, 0x9C100D4C, 0x4CC5D4BE, 0xCB3E42B6, 0x597F299C,
- 0xFC657E2A, 0x5FCB6FAB, 0x3AD6FAEC, 0x6C44198C, 0x4A475817
- };
- int t, t2, t8; /* Loop counter */
- uint32_t temp1[2], temp2[2], /* Temporary word values */
- temp3[2], temp4[2], temp5[2];
- uint32_t W[2*80]; /* Word sequence */
- uint32_t A[2], B[2], C[2], D[2], /* Word buffers */
- E[2], F[2], G[2], H[2];
-
- /* Initialize the first 16 words in the array W */
- for (t = t2 = t8 = 0; t < 16; t++, t8 += 8) {
- W[t2++] = ((((uint32_t)context->Message_Block[t8 ])) << 24) |
- ((((uint32_t)context->Message_Block[t8 + 1])) << 16) |
- ((((uint32_t)context->Message_Block[t8 + 2])) << 8) |
- ((((uint32_t)context->Message_Block[t8 + 3])));
- W[t2++] = ((((uint32_t)context->Message_Block[t8 + 4])) << 24) |
- ((((uint32_t)context->Message_Block[t8 + 5])) << 16) |
- ((((uint32_t)context->Message_Block[t8 + 6])) << 8) |
- ((((uint32_t)context->Message_Block[t8 + 7])));
- }
-
- for (t = 16; t < 80; t++, t2 += 2) {
- /* W[t] = SHA512_sigma1(W[t-2]) + W[t-7] +
- SHA512_sigma0(W[t-15]) + W[t-16]; */
- uint32_t *Wt2 = &W[t2-2*2];
- uint32_t *Wt7 = &W[t2-7*2];
- uint32_t *Wt15 = &W[t2-15*2];
- uint32_t *Wt16 = &W[t2-16*2];
- SHA512_sigma1(Wt2, temp1);
- SHA512_ADD(temp1, Wt7, temp2);
- SHA512_sigma0(Wt15, temp1);
- SHA512_ADD(temp1, Wt16, temp3);
- SHA512_ADD(temp2, temp3, &W[t2]);
- }
-
- A[0] = context->Intermediate_Hash[0];
-
-
-
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-
-
- A[1] = context->Intermediate_Hash[1];
- B[0] = context->Intermediate_Hash[2];
- B[1] = context->Intermediate_Hash[3];
- C[0] = context->Intermediate_Hash[4];
- C[1] = context->Intermediate_Hash[5];
- D[0] = context->Intermediate_Hash[6];
- D[1] = context->Intermediate_Hash[7];
- E[0] = context->Intermediate_Hash[8];
- E[1] = context->Intermediate_Hash[9];
- F[0] = context->Intermediate_Hash[10];
- F[1] = context->Intermediate_Hash[11];
- G[0] = context->Intermediate_Hash[12];
- G[1] = context->Intermediate_Hash[13];
- H[0] = context->Intermediate_Hash[14];
- H[1] = context->Intermediate_Hash[15];
-
- for (t = t2 = 0; t < 80; t++, t2 += 2) {
- /*
- * temp1 = H + SHA512_SIGMA1(E) + SHA_Ch(E,F,G) + K[t] + W[t];
- */
- SHA512_SIGMA1(E,temp1);
- SHA512_ADD(H, temp1, temp2);
- SHA_Ch(E,F,G,temp3);
- SHA512_ADD(temp2, temp3, temp4);
- SHA512_ADD(&K[t2], &W[t2], temp5);
- SHA512_ADD(temp4, temp5, temp1);
- /*
- * temp2 = SHA512_SIGMA0(A) + SHA_Maj(A,B,C);
- */
- SHA512_SIGMA0(A,temp3);
- SHA_Maj(A,B,C,temp4);
- SHA512_ADD(temp3, temp4, temp2);
- H[0] = G[0]; H[1] = G[1];
- G[0] = F[0]; G[1] = F[1];
- F[0] = E[0]; F[1] = E[1];
- SHA512_ADD(D, temp1, E);
- D[0] = C[0]; D[1] = C[1];
- C[0] = B[0]; C[1] = B[1];
- B[0] = A[0]; B[1] = A[1];
- SHA512_ADD(temp1, temp2, A);
- }
-
- SHA512_ADDTO2(&context->Intermediate_Hash[0], A);
- SHA512_ADDTO2(&context->Intermediate_Hash[2], B);
- SHA512_ADDTO2(&context->Intermediate_Hash[4], C);
- SHA512_ADDTO2(&context->Intermediate_Hash[6], D);
- SHA512_ADDTO2(&context->Intermediate_Hash[8], E);
- SHA512_ADDTO2(&context->Intermediate_Hash[10], F);
-
-
-
-Eastlake 3rd & Hansen Informational [Page 62]
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-
-
- SHA512_ADDTO2(&context->Intermediate_Hash[12], G);
- SHA512_ADDTO2(&context->Intermediate_Hash[14], H);
-
-#else /* !USE_32BIT_ONLY */
- static const uint64_t K[80] = {
- 0x428A2F98D728AE22ll, 0x7137449123EF65CDll, 0xB5C0FBCFEC4D3B2Fll,
- 0xE9B5DBA58189DBBCll, 0x3956C25BF348B538ll, 0x59F111F1B605D019ll,
- 0x923F82A4AF194F9Bll, 0xAB1C5ED5DA6D8118ll, 0xD807AA98A3030242ll,
- 0x12835B0145706FBEll, 0x243185BE4EE4B28Cll, 0x550C7DC3D5FFB4E2ll,
- 0x72BE5D74F27B896Fll, 0x80DEB1FE3B1696B1ll, 0x9BDC06A725C71235ll,
- 0xC19BF174CF692694ll, 0xE49B69C19EF14AD2ll, 0xEFBE4786384F25E3ll,
- 0x0FC19DC68B8CD5B5ll, 0x240CA1CC77AC9C65ll, 0x2DE92C6F592B0275ll,
- 0x4A7484AA6EA6E483ll, 0x5CB0A9DCBD41FBD4ll, 0x76F988DA831153B5ll,
- 0x983E5152EE66DFABll, 0xA831C66D2DB43210ll, 0xB00327C898FB213Fll,
- 0xBF597FC7BEEF0EE4ll, 0xC6E00BF33DA88FC2ll, 0xD5A79147930AA725ll,
- 0x06CA6351E003826Fll, 0x142929670A0E6E70ll, 0x27B70A8546D22FFCll,
- 0x2E1B21385C26C926ll, 0x4D2C6DFC5AC42AEDll, 0x53380D139D95B3DFll,
- 0x650A73548BAF63DEll, 0x766A0ABB3C77B2A8ll, 0x81C2C92E47EDAEE6ll,
- 0x92722C851482353Bll, 0xA2BFE8A14CF10364ll, 0xA81A664BBC423001ll,
- 0xC24B8B70D0F89791ll, 0xC76C51A30654BE30ll, 0xD192E819D6EF5218ll,
- 0xD69906245565A910ll, 0xF40E35855771202All, 0x106AA07032BBD1B8ll,
- 0x19A4C116B8D2D0C8ll, 0x1E376C085141AB53ll, 0x2748774CDF8EEB99ll,
- 0x34B0BCB5E19B48A8ll, 0x391C0CB3C5C95A63ll, 0x4ED8AA4AE3418ACBll,
- 0x5B9CCA4F7763E373ll, 0x682E6FF3D6B2B8A3ll, 0x748F82EE5DEFB2FCll,
- 0x78A5636F43172F60ll, 0x84C87814A1F0AB72ll, 0x8CC702081A6439ECll,
- 0x90BEFFFA23631E28ll, 0xA4506CEBDE82BDE9ll, 0xBEF9A3F7B2C67915ll,
- 0xC67178F2E372532Bll, 0xCA273ECEEA26619Cll, 0xD186B8C721C0C207ll,
- 0xEADA7DD6CDE0EB1Ell, 0xF57D4F7FEE6ED178ll, 0x06F067AA72176FBAll,
- 0x0A637DC5A2C898A6ll, 0x113F9804BEF90DAEll, 0x1B710B35131C471Bll,
- 0x28DB77F523047D84ll, 0x32CAAB7B40C72493ll, 0x3C9EBE0A15C9BEBCll,
- 0x431D67C49C100D4Cll, 0x4CC5D4BECB3E42B6ll, 0x597F299CFC657E2All,
- 0x5FCB6FAB3AD6FAECll, 0x6C44198C4A475817ll
- };
- int t, t8; /* Loop counter */
- uint64_t temp1, temp2; /* Temporary word value */
- uint64_t W[80]; /* Word sequence */
- uint64_t A, B, C, D, E, F, G, H; /* Word buffers */
-
- /*
- * Initialize the first 16 words in the array W
- */
- for (t = t8 = 0; t < 16; t++, t8 += 8)
- W[t] = ((uint64_t)(context->Message_Block[t8 ]) << 56) |
- ((uint64_t)(context->Message_Block[t8 + 1]) << 48) |
- ((uint64_t)(context->Message_Block[t8 + 2]) << 40) |
- ((uint64_t)(context->Message_Block[t8 + 3]) << 32) |
- ((uint64_t)(context->Message_Block[t8 + 4]) << 24) |
- ((uint64_t)(context->Message_Block[t8 + 5]) << 16) |
-
-
-
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-
-
- ((uint64_t)(context->Message_Block[t8 + 6]) << 8) |
- ((uint64_t)(context->Message_Block[t8 + 7]));
-
- for (t = 16; t < 80; t++)
- W[t] = SHA512_sigma1(W[t-2]) + W[t-7] +
- SHA512_sigma0(W[t-15]) + W[t-16];
-
- A = context->Intermediate_Hash[0];
- B = context->Intermediate_Hash[1];
- C = context->Intermediate_Hash[2];
- D = context->Intermediate_Hash[3];
- E = context->Intermediate_Hash[4];
- F = context->Intermediate_Hash[5];
- G = context->Intermediate_Hash[6];
- H = context->Intermediate_Hash[7];
-
- for (t = 0; t < 80; t++) {
- temp1 = H + SHA512_SIGMA1(E) + SHA_Ch(E,F,G) + K[t] + W[t];
- temp2 = SHA512_SIGMA0(A) + SHA_Maj(A,B,C);
- H = G;
- G = F;
- F = E;
- E = D + temp1;
- D = C;
- C = B;
- B = A;
- A = temp1 + temp2;
- }
-
- context->Intermediate_Hash[0] += A;
- context->Intermediate_Hash[1] += B;
- context->Intermediate_Hash[2] += C;
- context->Intermediate_Hash[3] += D;
- context->Intermediate_Hash[4] += E;
- context->Intermediate_Hash[5] += F;
- context->Intermediate_Hash[6] += G;
- context->Intermediate_Hash[7] += H;
-#endif /* USE_32BIT_ONLY */
-
- context->Message_Block_Index = 0;
-}
-
-/*
- * SHA384_512Reset
- *
- * Description:
- * This helper function will initialize the SHA512Context in
- * preparation for computing a new SHA384 or SHA512 message
-
-
-
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-
-
- * digest.
- *
- * Parameters:
- * context: [in/out]
- * The context to reset.
- * H0
- * The initial hash value to use.
- *
- * Returns:
- * sha Error Code.
- *
- */
-#ifdef USE_32BIT_ONLY
-static int SHA384_512Reset(SHA512Context *context, uint32_t H0[])
-#else /* !USE_32BIT_ONLY */
-static int SHA384_512Reset(SHA512Context *context, uint64_t H0[])
-#endif /* USE_32BIT_ONLY */
-{
- int i;
- if (!context)
- return shaNull;
-
- context->Message_Block_Index = 0;
-
-#ifdef USE_32BIT_ONLY
- context->Length[0] = context->Length[1] = 0;
- context->Length[2] = context->Length[3] = 0;
-
- for (i = 0; i < SHA512HashSize/4; i++)
- context->Intermediate_Hash[i] = H0[i];
-#else /* !USE_32BIT_ONLY */
- context->Length_High = context->Length_Low = 0;
-
- for (i = 0; i < SHA512HashSize/8; i++)
- context->Intermediate_Hash[i] = H0[i];
-#endif /* USE_32BIT_ONLY */
-
- context->Computed = 0;
- context->Corrupted = 0;
-
- return shaSuccess;
-}
-
-/*
- * SHA384_512ResultN
- *
- * Description:
- * This helper function will return the 384-bit or 512-bit message
-
-
-
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-
-
- * digest into the Message_Digest array provided by the caller.
- * NOTE: The first octet of hash is stored in the 0th element,
- * the last octet of hash in the 48th/64th element.
- *
- * Parameters:
- * context: [in/out]
- * The context to use to calculate the SHA hash.
- * Message_Digest: [out]
- * Where the digest is returned.
- * HashSize: [in]
- * The size of the hash, either 48 or 64.
- *
- * Returns:
- * sha Error Code.
- *
- */
-static int SHA384_512ResultN(SHA512Context *context,
- uint8_t Message_Digest[], int HashSize)
-{
- int i;
-
-#ifdef USE_32BIT_ONLY
- int i2;
-#endif /* USE_32BIT_ONLY */
-
- if (!context || !Message_Digest)
- return shaNull;
-
- if (context->Corrupted)
- return context->Corrupted;
-
- if (!context->Computed)
- SHA384_512Finalize(context, 0x80);
-
-#ifdef USE_32BIT_ONLY
- for (i = i2 = 0; i < HashSize; ) {
- Message_Digest[i++]=(uint8_t)(context->Intermediate_Hash[i2]>>24);
- Message_Digest[i++]=(uint8_t)(context->Intermediate_Hash[i2]>>16);
- Message_Digest[i++]=(uint8_t)(context->Intermediate_Hash[i2]>>8);
- Message_Digest[i++]=(uint8_t)(context->Intermediate_Hash[i2++]);
- Message_Digest[i++]=(uint8_t)(context->Intermediate_Hash[i2]>>24);
- Message_Digest[i++]=(uint8_t)(context->Intermediate_Hash[i2]>>16);
- Message_Digest[i++]=(uint8_t)(context->Intermediate_Hash[i2]>>8);
- Message_Digest[i++]=(uint8_t)(context->Intermediate_Hash[i2++]);
- }
-#else /* !USE_32BIT_ONLY */
- for (i = 0; i < HashSize; ++i)
- Message_Digest[i] = (uint8_t)
-
-
-
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-
-
- (context->Intermediate_Hash[i>>3] >> 8 * ( 7 - ( i % 8 ) ));
-#endif /* USE_32BIT_ONLY */
-
- return shaSuccess;
-}
-
-8.2.4. usha.c
-
-/**************************** usha.c ****************************/
-/******************** See RFC 4634 for details ******************/
-/*
- * Description:
- * This file implements a unified interface to the SHA algorithms.
- */
-
-#include "sha.h"
-
-/*
- * USHAReset
- *
- * Description:
- * This function will initialize the SHA Context in preparation
- * for computing a new SHA message digest.
- *
- * Parameters:
- * context: [in/out]
- * The context to reset.
- * whichSha: [in]
- * Selects which SHA reset to call
- *
- * Returns:
- * sha Error Code.
- *
- */
-int USHAReset(USHAContext *ctx, enum SHAversion whichSha)
-{
- if (ctx) {
- ctx->whichSha = whichSha;
- switch (whichSha) {
- case SHA1: return SHA1Reset((SHA1Context*)&ctx->ctx);
- case SHA224: return SHA224Reset((SHA224Context*)&ctx->ctx);
- case SHA256: return SHA256Reset((SHA256Context*)&ctx->ctx);
- case SHA384: return SHA384Reset((SHA384Context*)&ctx->ctx);
- case SHA512: return SHA512Reset((SHA512Context*)&ctx->ctx);
- default: return shaBadParam;
- }
- } else {
- return shaNull;
-
-
-
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-
-
- }
-}
-
-/*
- * USHAInput
- *
- * Description:
- * This function accepts an array of octets as the next portion
- * of the message.
- *
- * Parameters:
- * context: [in/out]
- * The SHA context to update
- * message_array: [in]
- * An array of characters representing the next portion of
- * the message.
- * length: [in]
- * The length of the message in message_array
- *
- * Returns:
- * sha Error Code.
- *
- */
-int USHAInput(USHAContext *ctx,
- const uint8_t *bytes, unsigned int bytecount)
-{
- if (ctx) {
- switch (ctx->whichSha) {
- case SHA1:
- return SHA1Input((SHA1Context*)&ctx->ctx, bytes, bytecount);
- case SHA224:
- return SHA224Input((SHA224Context*)&ctx->ctx, bytes,
- bytecount);
- case SHA256:
- return SHA256Input((SHA256Context*)&ctx->ctx, bytes,
- bytecount);
- case SHA384:
- return SHA384Input((SHA384Context*)&ctx->ctx, bytes,
- bytecount);
- case SHA512:
- return SHA512Input((SHA512Context*)&ctx->ctx, bytes,
- bytecount);
- default: return shaBadParam;
- }
- } else {
- return shaNull;
- }
-}
-
-
-
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-
-
-/*
- * USHAFinalBits
- *
- * Description:
- * This function will add in any final bits of the message.
- *
- * Parameters:
- * context: [in/out]
- * The SHA context to update
- * message_bits: [in]
- * The final bits of the message, in the upper portion of the
- * byte. (Use 0b###00000 instead of 0b00000### to input the
- * three bits ###.)
- * length: [in]
- * The number of bits in message_bits, between 1 and 7.
- *
- * Returns:
- * sha Error Code.
- */
-int USHAFinalBits(USHAContext *ctx,
- const uint8_t bits, unsigned int bitcount)
-{
- if (ctx) {
- switch (ctx->whichSha) {
- case SHA1:
- return SHA1FinalBits((SHA1Context*)&ctx->ctx, bits, bitcount);
- case SHA224:
- return SHA224FinalBits((SHA224Context*)&ctx->ctx, bits,
- bitcount);
- case SHA256:
- return SHA256FinalBits((SHA256Context*)&ctx->ctx, bits,
- bitcount);
- case SHA384:
- return SHA384FinalBits((SHA384Context*)&ctx->ctx, bits,
- bitcount);
- case SHA512:
- return SHA512FinalBits((SHA512Context*)&ctx->ctx, bits,
- bitcount);
- default: return shaBadParam;
- }
- } else {
- return shaNull;
- }
-}
-
-/*
- * USHAResult
- *
-
-
-
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-
-
- * Description:
- * This function will return the 160-bit message digest into the
- * Message_Digest array provided by the caller.
- * NOTE: The first octet of hash is stored in the 0th element,
- * the last octet of hash in the 19th element.
- *
- * Parameters:
- * context: [in/out]
- * The context to use to calculate the SHA-1 hash.
- * Message_Digest: [out]
- * Where the digest is returned.
- *
- * Returns:
- * sha Error Code.
- *
- */
-int USHAResult(USHAContext *ctx,
- uint8_t Message_Digest[USHAMaxHashSize])
-{
- if (ctx) {
- switch (ctx->whichSha) {
- case SHA1:
- return SHA1Result((SHA1Context*)&ctx->ctx, Message_Digest);
- case SHA224:
- return SHA224Result((SHA224Context*)&ctx->ctx, Message_Digest);
- case SHA256:
- return SHA256Result((SHA256Context*)&ctx->ctx, Message_Digest);
- case SHA384:
- return SHA384Result((SHA384Context*)&ctx->ctx, Message_Digest);
- case SHA512:
- return SHA512Result((SHA512Context*)&ctx->ctx, Message_Digest);
- default: return shaBadParam;
- }
- } else {
- return shaNull;
- }
-}
-
-/*
- * USHABlockSize
- *
- * Description:
- * This function will return the blocksize for the given SHA
- * algorithm.
- *
- * Parameters:
- * whichSha:
- * which SHA algorithm to query
-
-
-
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-
-
- *
- * Returns:
- * block size
- *
- */
-int USHABlockSize(enum SHAversion whichSha)
-{
- switch (whichSha) {
- case SHA1: return SHA1_Message_Block_Size;
- case SHA224: return SHA224_Message_Block_Size;
- case SHA256: return SHA256_Message_Block_Size;
- case SHA384: return SHA384_Message_Block_Size;
- default:
- case SHA512: return SHA512_Message_Block_Size;
- }
-}
-
-/*
- * USHAHashSize
- *
- * Description:
- * This function will return the hashsize for the given SHA
- * algorithm.
- *
- * Parameters:
- * whichSha:
- * which SHA algorithm to query
- *
- * Returns:
- * hash size
- *
- */
-int USHAHashSize(enum SHAversion whichSha)
-{
- switch (whichSha) {
- case SHA1: return SHA1HashSize;
- case SHA224: return SHA224HashSize;
- case SHA256: return SHA256HashSize;
- case SHA384: return SHA384HashSize;
- default:
- case SHA512: return SHA512HashSize;
- }
-}
-
-/*
- * USHAHashSizeBits
- *
- * Description:
-
-
-
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-
-
- * This function will return the hashsize for the given SHA
- * algorithm, expressed in bits.
- *
- * Parameters:
- * whichSha:
- * which SHA algorithm to query
- *
- * Returns:
- * hash size in bits
- *
- */
-int USHAHashSizeBits(enum SHAversion whichSha)
-{
- switch (whichSha) {
- case SHA1: return SHA1HashSizeBits;
- case SHA224: return SHA224HashSizeBits;
- case SHA256: return SHA256HashSizeBits;
- case SHA384: return SHA384HashSizeBits;
- default:
- case SHA512: return SHA512HashSizeBits;
- }
-}
-
-8.2.5. sha-private.h
-
-/*************************** sha-private.h ***************************/
-/********************** See RFC 4634 for details *********************/
-#ifndef _SHA_PRIVATE__H
-#define _SHA_PRIVATE__H
-/*
- * These definitions are defined in FIPS-180-2, section 4.1.
- * Ch() and Maj() are defined identically in sections 4.1.1,
- * 4.1.2 and 4.1.3.
- *
- * The definitions used in FIPS-180-2 are as follows:
- */
-
-#ifndef USE_MODIFIED_MACROS
-#define SHA_Ch(x,y,z) (((x) & (y)) ^ ((~(x)) & (z)))
-#define SHA_Maj(x,y,z) (((x) & (y)) ^ ((x) & (z)) ^ ((y) & (z)))
-
-#else /* USE_MODIFIED_MACROS */
-/*
- * The following definitions are equivalent and potentially faster.
- */
-
-#define SHA_Ch(x, y, z) (((x) & ((y) ^ (z))) ^ (z))
-#define SHA_Maj(x, y, z) (((x) & ((y) | (z))) | ((y) & (z)))
-
-
-
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-
-
-#endif /* USE_MODIFIED_MACROS */
-
-#define SHA_Parity(x, y, z) ((x) ^ (y) ^ (z))
-
-#endif /* _SHA_PRIVATE__H */
-
-8.3 The HMAC Code
-
-/**************************** hmac.c ****************************/
-/******************** See RFC 4634 for details ******************/
-/*
- * Description:
- * This file implements the HMAC algorithm (Keyed-Hashing for
- * Message Authentication, RFC2104), expressed in terms of the
- * various SHA algorithms.
- */
-
-#include "sha.h"
-
-/*
- * hmac
- *
- * Description:
- * This function will compute an HMAC message digest.
- *
- * Parameters:
- * whichSha: [in]
- * One of SHA1, SHA224, SHA256, SHA384, SHA512
- * key: [in]
- * The secret shared key.
- * key_len: [in]
- * The length of the secret shared key.
- * message_array: [in]
- * An array of characters representing the message.
- * length: [in]
- * The length of the message in message_array
- * digest: [out]
- * Where the digest is returned.
- * NOTE: The length of the digest is determined by
- * the value of whichSha.
- *
- * Returns:
- * sha Error Code.
- *
- */
-int hmac(SHAversion whichSha, const unsigned char *text, int text_len,
- const unsigned char *key, int key_len,
- uint8_t digest[USHAMaxHashSize])
-
-
-
-Eastlake 3rd & Hansen Informational [Page 73]
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-
-
-{
- HMACContext ctx;
- return hmacReset(&ctx, whichSha, key, key_len) ||
- hmacInput(&ctx, text, text_len) ||
- hmacResult(&ctx, digest);
-}
-
-/*
- * hmacReset
- *
- * Description:
- * This function will initialize the hmacContext in preparation
- * for computing a new HMAC message digest.
- *
- * Parameters:
- * context: [in/out]
- * The context to reset.
- * whichSha: [in]
- * One of SHA1, SHA224, SHA256, SHA384, SHA512
- * key: [in]
- * The secret shared key.
- * key_len: [in]
- * The length of the secret shared key.
- *
- * Returns:
- * sha Error Code.
- *
- */
-int hmacReset(HMACContext *ctx, enum SHAversion whichSha,
- const unsigned char *key, int key_len)
-{
- int i, blocksize, hashsize;
-
- /* inner padding - key XORd with ipad */
- unsigned char k_ipad[USHA_Max_Message_Block_Size];
-
- /* temporary buffer when keylen > blocksize */
- unsigned char tempkey[USHAMaxHashSize];
-
- if (!ctx) return shaNull;
-
- blocksize = ctx->blockSize = USHABlockSize(whichSha);
- hashsize = ctx->hashSize = USHAHashSize(whichSha);
-
- ctx->whichSha = whichSha;
-
- /*
- * If key is longer than the hash blocksize,
-
-
-
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-
-
- * reset it to key = HASH(key).
- */
- if (key_len > blocksize) {
- USHAContext tctx;
- int err = USHAReset(&tctx, whichSha) ||
- USHAInput(&tctx, key, key_len) ||
- USHAResult(&tctx, tempkey);
- if (err != shaSuccess) return err;
-
- key = tempkey;
- key_len = hashsize;
- }
-
- /*
- * The HMAC transform looks like:
- *
- * SHA(K XOR opad, SHA(K XOR ipad, text))
- *
- * where K is an n byte key.
- * ipad is the byte 0x36 repeated blocksize times
- * opad is the byte 0x5c repeated blocksize times
- * and text is the data being protected.
- */
-
- /* store key into the pads, XOR'd with ipad and opad values */
- for (i = 0; i < key_len; i++) {
- k_ipad[i] = key[i] ^ 0x36;
- ctx->k_opad[i] = key[i] ^ 0x5c;
- }
- /* remaining pad bytes are '\0' XOR'd with ipad and opad values */
- for ( ; i < blocksize; i++) {
- k_ipad[i] = 0x36;
- ctx->k_opad[i] = 0x5c;
- }
-
- /* perform inner hash */
- /* init context for 1st pass */
- return USHAReset(&ctx->shaContext, whichSha) ||
- /* and start with inner pad */
- USHAInput(&ctx->shaContext, k_ipad, blocksize);
-}
-
-/*
- * hmacInput
- *
- * Description:
- * This function accepts an array of octets as the next portion
- * of the message.
-
-
-
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-RFC 4634 SHAs and HMAC-SHAs July 2006
-
-
- *
- * Parameters:
- * context: [in/out]
- * The HMAC context to update
- * message_array: [in]
- * An array of characters representing the next portion of
- * the message.
- * length: [in]
- * The length of the message in message_array
- *
- * Returns:
- * sha Error Code.
- *
- */
-int hmacInput(HMACContext *ctx, const unsigned char *text,
- int text_len)
-{
- if (!ctx) return shaNull;
- /* then text of datagram */
- return USHAInput(&ctx->shaContext, text, text_len);
-}
-
-/*
- * HMACFinalBits
- *
- * Description:
- * This function will add in any final bits of the message.
- *
- * Parameters:
- * context: [in/out]
- * The HMAC context to update
- * message_bits: [in]
- * The final bits of the message, in the upper portion of the
- * byte. (Use 0b###00000 instead of 0b00000### to input the
- * three bits ###.)
- * length: [in]
- * The number of bits in message_bits, between 1 and 7.
- *
- * Returns:
- * sha Error Code.
- */
-int hmacFinalBits(HMACContext *ctx,
- const uint8_t bits,
- unsigned int bitcount)
-{
- if (!ctx) return shaNull;
- /* then final bits of datagram */
- return USHAFinalBits(&ctx->shaContext, bits, bitcount);
-
-
-
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-
-
-}
-
-/*
- * HMACResult
- *
- * Description:
- * This function will return the N-byte message digest into the
- * Message_Digest array provided by the caller.
- * NOTE: The first octet of hash is stored in the 0th element,
- * the last octet of hash in the Nth element.
- *
- * Parameters:
- * context: [in/out]
- * The context to use to calculate the HMAC hash.
- * digest: [out]
- * Where the digest is returned.
- * NOTE 2: The length of the hash is determined by the value of
- * whichSha that was passed to hmacReset().
- *
- * Returns:
- * sha Error Code.
- *
- */
-int hmacResult(HMACContext *ctx, uint8_t *digest)
-{
- if (!ctx) return shaNull;
-
- /* finish up 1st pass */
- /* (Use digest here as a temporary buffer.) */
- return USHAResult(&ctx->shaContext, digest) ||
-
- /* perform outer SHA */
- /* init context for 2nd pass */
- USHAReset(&ctx->shaContext, ctx->whichSha) ||
-
- /* start with outer pad */
- USHAInput(&ctx->shaContext, ctx->k_opad, ctx->blockSize) ||
-
- /* then results of 1st hash */
- USHAInput(&ctx->shaContext, digest, ctx->hashSize) ||
-
- /* finish up 2nd pass */
- USHAResult(&ctx->shaContext, digest);
-}
-
-
-
-
-
-
-
-Eastlake 3rd & Hansen Informational [Page 77]
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-RFC 4634 SHAs and HMAC-SHAs July 2006
-
-
-8.4. The Test Driver
-
- The following code is a main program test driver to exercise the code
- in sha1.c, sha224-256.c, and sha384-512.c. The test driver can also
- be used as a stand-alone program for generating the hashes.
-
- See also [RFC2202], [RFC4231], and [SHAVS].
-
-/**************************** shatest.c ****************************/
-/********************* See RFC 4634 for details ********************/
-/*
- * Description:
- * This file will exercise the SHA code performing
- * the three tests documented in FIPS PUB 180-2
- * (http://csrc.nist.gov/publications/fips/
- * fips180-2/fips180-2withchangenotice.pdf)
- * one that calls SHAInput with an exact multiple of 512 bits
- * the seven tests documented for each algorithm in
- * "The Secure Hash Algorithm Validation System (SHAVS)",
- * three of which are bit-level tests
- * (http://csrc.nist.gov/cryptval/shs/SHAVS.pdf)
- *
- * This file will exercise the HMAC SHA1 code performing
- * the seven tests documented in RFCs 2202 and 4231.
- *
- * To run the tests and just see PASSED/FAILED, use the -p option.
- *
- * Other options exercise:
- * hashing an arbitrary string
- * hashing a file's contents
- * a few error test checks
- * printing the results in raw format
- *
- * Portability Issues:
- * None.
- *
- */
-
-#include <stdint.h>
-#include <stdio.h>
-#include <stdlib.h>
-#include <string.h>
-#include <ctype.h>
-#include "sha.h"
-
-static int xgetopt(int argc, char **argv, const char *optstring);
-extern char *xoptarg;
-static int scasecmp(const char *s1, const char *s2);
-
-
-
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-
-
-/*
- * Define patterns for testing
- */
-#define TEST1 "abc"
-#define TEST2_1 \
- "abcdbcdecdefdefgefghfghighijhijkijkljklmklmnlmnomnopnopq"
-#define TEST2_2a \
- "abcdefghbcdefghicdefghijdefghijkefghijklfghijklmghijklmn"
-#define TEST2_2b \
- "hijklmnoijklmnopjklmnopqklmnopqrlmnopqrsmnopqrstnopqrstu"
-#define TEST2_2 TEST2_2a TEST2_2b
-#define TEST3 "a" /* times 1000000 */
-#define TEST4a "01234567012345670123456701234567"
-#define TEST4b "01234567012345670123456701234567"
- /* an exact multiple of 512 bits */
-#define TEST4 TEST4a TEST4b /* times 10 */
-
-#define TEST7_1 \
- "\x49\xb2\xae\xc2\x59\x4b\xbe\x3a\x3b\x11\x75\x42\xd9\x4a\xc8"
-#define TEST8_1 \
- "\x9a\x7d\xfd\xf1\xec\xea\xd0\x6e\xd6\x46\xaa\x55\xfe\x75\x71\x46"
-#define TEST9_1 \
- "\x65\xf9\x32\x99\x5b\xa4\xce\x2c\xb1\xb4\xa2\xe7\x1a\xe7\x02\x20" \
- "\xaa\xce\xc8\x96\x2d\xd4\x49\x9c\xbd\x7c\x88\x7a\x94\xea\xaa\x10" \
- "\x1e\xa5\xaa\xbc\x52\x9b\x4e\x7e\x43\x66\x5a\x5a\xf2\xcd\x03\xfe" \
- "\x67\x8e\xa6\xa5\x00\x5b\xba\x3b\x08\x22\x04\xc2\x8b\x91\x09\xf4" \
- "\x69\xda\xc9\x2a\xaa\xb3\xaa\x7c\x11\xa1\xb3\x2a"
-#define TEST10_1 \
- "\xf7\x8f\x92\x14\x1b\xcd\x17\x0a\xe8\x9b\x4f\xba\x15\xa1\xd5\x9f" \
- "\x3f\xd8\x4d\x22\x3c\x92\x51\xbd\xac\xbb\xae\x61\xd0\x5e\xd1\x15" \
- "\xa0\x6a\x7c\xe1\x17\xb7\xbe\xea\xd2\x44\x21\xde\xd9\xc3\x25\x92" \
- "\xbd\x57\xed\xea\xe3\x9c\x39\xfa\x1f\xe8\x94\x6a\x84\xd0\xcf\x1f" \
- "\x7b\xee\xad\x17\x13\xe2\xe0\x95\x98\x97\x34\x7f\x67\xc8\x0b\x04" \
- "\x00\xc2\x09\x81\x5d\x6b\x10\xa6\x83\x83\x6f\xd5\x56\x2a\x56\xca" \
- "\xb1\xa2\x8e\x81\xb6\x57\x66\x54\x63\x1c\xf1\x65\x66\xb8\x6e\x3b" \
- "\x33\xa1\x08\xb0\x53\x07\xc0\x0a\xff\x14\xa7\x68\xed\x73\x50\x60" \
- "\x6a\x0f\x85\xe6\xa9\x1d\x39\x6f\x5b\x5c\xbe\x57\x7f\x9b\x38\x80" \
- "\x7c\x7d\x52\x3d\x6d\x79\x2f\x6e\xbc\x24\xa4\xec\xf2\xb3\xa4\x27" \
- "\xcd\xbb\xfb"
-#define TEST7_224 \
- "\xf0\x70\x06\xf2\x5a\x0b\xea\x68\xcd\x76\xa2\x95\x87\xc2\x8d"
-#define TEST8_224 \
- "\x18\x80\x40\x05\xdd\x4f\xbd\x15\x56\x29\x9d\x6f\x9d\x93\xdf\x62"
-#define TEST9_224 \
- "\xa2\xbe\x6e\x46\x32\x81\x09\x02\x94\xd9\xce\x94\x82\x65\x69\x42" \
- "\x3a\x3a\x30\x5e\xd5\xe2\x11\x6c\xd4\xa4\xc9\x87\xfc\x06\x57\x00" \
- "\x64\x91\xb1\x49\xcc\xd4\xb5\x11\x30\xac\x62\xb1\x9d\xc2\x48\xc7" \
- "\x44\x54\x3d\x20\xcd\x39\x52\xdc\xed\x1f\x06\xcc\x3b\x18\xb9\x1f" \
-
-
-
-Eastlake 3rd & Hansen Informational [Page 79]
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-
-
- "\x3f\x55\x63\x3e\xcc\x30\x85\xf4\x90\x70\x60\xd2"
-#define TEST10_224 \
- "\x55\xb2\x10\x07\x9c\x61\xb5\x3a\xdd\x52\x06\x22\xd1\xac\x97\xd5" \
- "\xcd\xbe\x8c\xb3\x3a\xa0\xae\x34\x45\x17\xbe\xe4\xd7\xba\x09\xab" \
- "\xc8\x53\x3c\x52\x50\x88\x7a\x43\xbe\xbb\xac\x90\x6c\x2e\x18\x37" \
- "\xf2\x6b\x36\xa5\x9a\xe3\xbe\x78\x14\xd5\x06\x89\x6b\x71\x8b\x2a" \
- "\x38\x3e\xcd\xac\x16\xb9\x61\x25\x55\x3f\x41\x6f\xf3\x2c\x66\x74" \
- "\xc7\x45\x99\xa9\x00\x53\x86\xd9\xce\x11\x12\x24\x5f\x48\xee\x47" \
- "\x0d\x39\x6c\x1e\xd6\x3b\x92\x67\x0c\xa5\x6e\xc8\x4d\xee\xa8\x14" \
- "\xb6\x13\x5e\xca\x54\x39\x2b\xde\xdb\x94\x89\xbc\x9b\x87\x5a\x8b" \
- "\xaf\x0d\xc1\xae\x78\x57\x36\x91\x4a\xb7\xda\xa2\x64\xbc\x07\x9d" \
- "\x26\x9f\x2c\x0d\x7e\xdd\xd8\x10\xa4\x26\x14\x5a\x07\x76\xf6\x7c" \
- "\x87\x82\x73"
-#define TEST7_256 \
- "\xbe\x27\x46\xc6\xdb\x52\x76\x5f\xdb\x2f\x88\x70\x0f\x9a\x73"
-#define TEST8_256 \
- "\xe3\xd7\x25\x70\xdc\xdd\x78\x7c\xe3\x88\x7a\xb2\xcd\x68\x46\x52"
-#define TEST9_256 \
- "\x3e\x74\x03\x71\xc8\x10\xc2\xb9\x9f\xc0\x4e\x80\x49\x07\xef\x7c" \
- "\xf2\x6b\xe2\x8b\x57\xcb\x58\xa3\xe2\xf3\xc0\x07\x16\x6e\x49\xc1" \
- "\x2e\x9b\xa3\x4c\x01\x04\x06\x91\x29\xea\x76\x15\x64\x25\x45\x70" \
- "\x3a\x2b\xd9\x01\xe1\x6e\xb0\xe0\x5d\xeb\xa0\x14\xeb\xff\x64\x06" \
- "\xa0\x7d\x54\x36\x4e\xff\x74\x2d\xa7\x79\xb0\xb3"
-#define TEST10_256 \
- "\x83\x26\x75\x4e\x22\x77\x37\x2f\x4f\xc1\x2b\x20\x52\x7a\xfe\xf0" \
- "\x4d\x8a\x05\x69\x71\xb1\x1a\xd5\x71\x23\xa7\xc1\x37\x76\x00\x00" \
- "\xd7\xbe\xf6\xf3\xc1\xf7\xa9\x08\x3a\xa3\x9d\x81\x0d\xb3\x10\x77" \
- "\x7d\xab\x8b\x1e\x7f\x02\xb8\x4a\x26\xc7\x73\x32\x5f\x8b\x23\x74" \
- "\xde\x7a\x4b\x5a\x58\xcb\x5c\x5c\xf3\x5b\xce\xe6\xfb\x94\x6e\x5b" \
- "\xd6\x94\xfa\x59\x3a\x8b\xeb\x3f\x9d\x65\x92\xec\xed\xaa\x66\xca" \
- "\x82\xa2\x9d\x0c\x51\xbc\xf9\x33\x62\x30\xe5\xd7\x84\xe4\xc0\xa4" \
- "\x3f\x8d\x79\xa3\x0a\x16\x5c\xba\xbe\x45\x2b\x77\x4b\x9c\x71\x09" \
- "\xa9\x7d\x13\x8f\x12\x92\x28\x96\x6f\x6c\x0a\xdc\x10\x6a\xad\x5a" \
- "\x9f\xdd\x30\x82\x57\x69\xb2\xc6\x71\xaf\x67\x59\xdf\x28\xeb\x39" \
- "\x3d\x54\xd6"
-#define TEST7_384 \
- "\x8b\xc5\x00\xc7\x7c\xee\xd9\x87\x9d\xa9\x89\x10\x7c\xe0\xaa"
-#define TEST8_384 \
- "\xa4\x1c\x49\x77\x79\xc0\x37\x5f\xf1\x0a\x7f\x4e\x08\x59\x17\x39"
-#define TEST9_384 \
- "\x68\xf5\x01\x79\x2d\xea\x97\x96\x76\x70\x22\xd9\x3d\xa7\x16\x79" \
- "\x30\x99\x20\xfa\x10\x12\xae\xa3\x57\xb2\xb1\x33\x1d\x40\xa1\xd0" \
- "\x3c\x41\xc2\x40\xb3\xc9\xa7\x5b\x48\x92\xf4\xc0\x72\x4b\x68\xc8" \
- "\x75\x32\x1a\xb8\xcf\xe5\x02\x3b\xd3\x75\xbc\x0f\x94\xbd\x89\xfe" \
- "\x04\xf2\x97\x10\x5d\x7b\x82\xff\xc0\x02\x1a\xeb\x1c\xcb\x67\x4f" \
- "\x52\x44\xea\x34\x97\xde\x26\xa4\x19\x1c\x5f\x62\xe5\xe9\xa2\xd8" \
- "\x08\x2f\x05\x51\xf4\xa5\x30\x68\x26\xe9\x1c\xc0\x06\xce\x1b\xf6" \
- "\x0f\xf7\x19\xd4\x2f\xa5\x21\xc8\x71\xcd\x23\x94\xd9\x6e\xf4\x46" \
-
-
-
-Eastlake 3rd & Hansen Informational [Page 80]
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-RFC 4634 SHAs and HMAC-SHAs July 2006
-
-
- "\x8f\x21\x96\x6b\x41\xf2\xba\x80\xc2\x6e\x83\xa9"
-#define TEST10_384 \
- "\x39\x96\x69\xe2\x8f\x6b\x9c\x6d\xbc\xbb\x69\x12\xec\x10\xff\xcf" \
- "\x74\x79\x03\x49\xb7\xdc\x8f\xbe\x4a\x8e\x7b\x3b\x56\x21\xdb\x0f" \
- "\x3e\x7d\xc8\x7f\x82\x32\x64\xbb\xe4\x0d\x18\x11\xc9\xea\x20\x61" \
- "\xe1\xc8\x4a\xd1\x0a\x23\xfa\xc1\x72\x7e\x72\x02\xfc\x3f\x50\x42" \
- "\xe6\xbf\x58\xcb\xa8\xa2\x74\x6e\x1f\x64\xf9\xb9\xea\x35\x2c\x71" \
- "\x15\x07\x05\x3c\xf4\xe5\x33\x9d\x52\x86\x5f\x25\xcc\x22\xb5\xe8" \
- "\x77\x84\xa1\x2f\xc9\x61\xd6\x6c\xb6\xe8\x95\x73\x19\x9a\x2c\xe6" \
- "\x56\x5c\xbd\xf1\x3d\xca\x40\x38\x32\xcf\xcb\x0e\x8b\x72\x11\xe8" \
- "\x3a\xf3\x2a\x11\xac\x17\x92\x9f\xf1\xc0\x73\xa5\x1c\xc0\x27\xaa" \
- "\xed\xef\xf8\x5a\xad\x7c\x2b\x7c\x5a\x80\x3e\x24\x04\xd9\x6d\x2a" \
- "\x77\x35\x7b\xda\x1a\x6d\xae\xed\x17\x15\x1c\xb9\xbc\x51\x25\xa4" \
- "\x22\xe9\x41\xde\x0c\xa0\xfc\x50\x11\xc2\x3e\xcf\xfe\xfd\xd0\x96" \
- "\x76\x71\x1c\xf3\xdb\x0a\x34\x40\x72\x0e\x16\x15\xc1\xf2\x2f\xbc" \
- "\x3c\x72\x1d\xe5\x21\xe1\xb9\x9b\xa1\xbd\x55\x77\x40\x86\x42\x14" \
- "\x7e\xd0\x96"
-#define TEST7_512 \
- "\x08\xec\xb5\x2e\xba\xe1\xf7\x42\x2d\xb6\x2b\xcd\x54\x26\x70"
-#define TEST8_512 \
- "\x8d\x4e\x3c\x0e\x38\x89\x19\x14\x91\x81\x6e\x9d\x98\xbf\xf0\xa0"
-#define TEST9_512 \
- "\x3a\xdd\xec\x85\x59\x32\x16\xd1\x61\x9a\xa0\x2d\x97\x56\x97\x0b" \
- "\xfc\x70\xac\xe2\x74\x4f\x7c\x6b\x27\x88\x15\x10\x28\xf7\xb6\xa2" \
- "\x55\x0f\xd7\x4a\x7e\x6e\x69\xc2\xc9\xb4\x5f\xc4\x54\x96\x6d\xc3" \
- "\x1d\x2e\x10\xda\x1f\x95\xce\x02\xbe\xb4\xbf\x87\x65\x57\x4c\xbd" \
- "\x6e\x83\x37\xef\x42\x0a\xdc\x98\xc1\x5c\xb6\xd5\xe4\xa0\x24\x1b" \
- "\xa0\x04\x6d\x25\x0e\x51\x02\x31\xca\xc2\x04\x6c\x99\x16\x06\xab" \
- "\x4e\xe4\x14\x5b\xee\x2f\xf4\xbb\x12\x3a\xab\x49\x8d\x9d\x44\x79" \
- "\x4f\x99\xcc\xad\x89\xa9\xa1\x62\x12\x59\xed\xa7\x0a\x5b\x6d\xd4" \
- "\xbd\xd8\x77\x78\xc9\x04\x3b\x93\x84\xf5\x49\x06"
-#define TEST10_512 \
- "\xa5\x5f\x20\xc4\x11\xaa\xd1\x32\x80\x7a\x50\x2d\x65\x82\x4e\x31" \
- "\xa2\x30\x54\x32\xaa\x3d\x06\xd3\xe2\x82\xa8\xd8\x4e\x0d\xe1\xde" \
- "\x69\x74\xbf\x49\x54\x69\xfc\x7f\x33\x8f\x80\x54\xd5\x8c\x26\xc4" \
- "\x93\x60\xc3\xe8\x7a\xf5\x65\x23\xac\xf6\xd8\x9d\x03\xe5\x6f\xf2" \
- "\xf8\x68\x00\x2b\xc3\xe4\x31\xed\xc4\x4d\xf2\xf0\x22\x3d\x4b\xb3" \
- "\xb2\x43\x58\x6e\x1a\x7d\x92\x49\x36\x69\x4f\xcb\xba\xf8\x8d\x95" \
- "\x19\xe4\xeb\x50\xa6\x44\xf8\xe4\xf9\x5e\xb0\xea\x95\xbc\x44\x65" \
- "\xc8\x82\x1a\xac\xd2\xfe\x15\xab\x49\x81\x16\x4b\xbb\x6d\xc3\x2f" \
- "\x96\x90\x87\xa1\x45\xb0\xd9\xcc\x9c\x67\xc2\x2b\x76\x32\x99\x41" \
- "\x9c\xc4\x12\x8b\xe9\xa0\x77\xb3\xac\xe6\x34\x06\x4e\x6d\x99\x28" \
- "\x35\x13\xdc\x06\xe7\x51\x5d\x0d\x73\x13\x2e\x9a\x0d\xc6\xd3\xb1" \
- "\xf8\xb2\x46\xf1\xa9\x8a\x3f\xc7\x29\x41\xb1\xe3\xbb\x20\x98\xe8" \
- "\xbf\x16\xf2\x68\xd6\x4f\x0b\x0f\x47\x07\xfe\x1e\xa1\xa1\x79\x1b" \
- "\xa2\xf3\xc0\xc7\x58\xe5\xf5\x51\x86\x3a\x96\xc9\x49\xad\x47\xd7" \
- "\xfb\x40\xd2"
-#define SHA1_SEED "\xd0\x56\x9c\xb3\x66\x5a\x8a\x43\xeb\x6e\xa2\x3d" \
-
-
-
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-
-
- "\x75\xa3\xc4\xd2\x05\x4a\x0d\x7d"
-#define SHA224_SEED "\xd0\x56\x9c\xb3\x66\x5a\x8a\x43\xeb\x6e\xa2" \
- "\x3d\x75\xa3\xc4\xd2\x05\x4a\x0d\x7d\x66\xa9\xca\x99\xc9\xce\xb0" \
- "\x27"
-#define SHA256_SEED "\xf4\x1e\xce\x26\x13\xe4\x57\x39\x15\x69\x6b" \
- "\x5a\xdc\xd5\x1c\xa3\x28\xbe\x3b\xf5\x66\xa9\xca\x99\xc9\xce\xb0" \
- "\x27\x9c\x1c\xb0\xa7"
-#define SHA384_SEED "\x82\x40\xbc\x51\xe4\xec\x7e\xf7\x6d\x18\xe3" \
- "\x52\x04\xa1\x9f\x51\xa5\x21\x3a\x73\xa8\x1d\x6f\x94\x46\x80\xd3" \
- "\x07\x59\x48\xb7\xe4\x63\x80\x4e\xa3\xd2\x6e\x13\xea\x82\x0d\x65" \
- "\xa4\x84\xbe\x74\x53"
-#define SHA512_SEED "\x47\x3f\xf1\xb9\xb3\xff\xdf\xa1\x26\x69\x9a" \
- "\xc7\xef\x9e\x8e\x78\x77\x73\x09\x58\x24\xc6\x42\x55\x7c\x13\x99" \
- "\xd9\x8e\x42\x20\x44\x8d\xc3\x5b\x99\xbf\xdd\x44\x77\x95\x43\x92" \
- "\x4c\x1c\xe9\x3b\xc5\x94\x15\x38\x89\x5d\xb9\x88\x26\x1b\x00\x77" \
- "\x4b\x12\x27\x20\x39"
-
-#define TESTCOUNT 10
-#define HASHCOUNT 5
-#define RANDOMCOUNT 4
-#define HMACTESTCOUNT 7
-
-#define PRINTNONE 0
-#define PRINTTEXT 1
-#define PRINTRAW 2
-#define PRINTHEX 3
-#define PRINTBASE64 4
-
-#define PRINTPASSFAIL 1
-#define PRINTFAIL 2
-
-#define length(x) (sizeof(x)-1)
-
-/* Test arrays for hashes. */
-struct hash {
- const char *name;
- SHAversion whichSha;
- int hashsize;
- struct {
- const char *testarray;
- int length;
- long repeatcount;
- int extrabits;
- int numberExtrabits;
- const char *resultarray;
- } tests[TESTCOUNT];
- const char *randomtest;
- const char *randomresults[RANDOMCOUNT];
-
-
-
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-
-
-} hashes[HASHCOUNT] = {
- { "SHA1", SHA1, SHA1HashSize,
- {
- /* 1 */ { TEST1, length(TEST1), 1, 0, 0,
- "A9993E364706816ABA3E25717850C26C9CD0D89D" },
- /* 2 */ { TEST2_1, length(TEST2_1), 1, 0, 0,
- "84983E441C3BD26EBAAE4AA1F95129E5E54670F1" },
- /* 3 */ { TEST3, length(TEST3), 1000000, 0, 0,
- "34AA973CD4C4DAA4F61EEB2BDBAD27316534016F" },
- /* 4 */ { TEST4, length(TEST4), 10, 0, 0,
- "DEA356A2CDDD90C7A7ECEDC5EBB563934F460452" },
- /* 5 */ { "", 0, 0, 0x98, 5,
- "29826B003B906E660EFF4027CE98AF3531AC75BA" },
- /* 6 */ { "\x5e", 1, 1, 0, 0,
- "5E6F80A34A9798CAFC6A5DB96CC57BA4C4DB59C2" },
- /* 7 */ { TEST7_1, length(TEST7_1), 1, 0x80, 3,
- "6239781E03729919C01955B3FFA8ACB60B988340" },
- /* 8 */ { TEST8_1, length(TEST8_1), 1, 0, 0,
- "82ABFF6605DBE1C17DEF12A394FA22A82B544A35" },
- /* 9 */ { TEST9_1, length(TEST9_1), 1, 0xE0, 3,
- "8C5B2A5DDAE5A97FC7F9D85661C672ADBF7933D4" },
- /* 10 */ { TEST10_1, length(TEST10_1), 1, 0, 0,
- "CB0082C8F197D260991BA6A460E76E202BAD27B3" }
- }, SHA1_SEED, { "E216836819477C7F78E0D843FE4FF1B6D6C14CD4",
- "A2DBC7A5B1C6C0A8BCB7AAA41252A6A7D0690DBC",
- "DB1F9050BB863DFEF4CE37186044E2EEB17EE013",
- "127FDEDF43D372A51D5747C48FBFFE38EF6CDF7B"
- } },
- { "SHA224", SHA224, SHA224HashSize,
- {
- /* 1 */ { TEST1, length(TEST1), 1, 0, 0,
- "23097D223405D8228642A477BDA255B32AADBCE4BDA0B3F7E36C9DA7" },
- /* 2 */ { TEST2_1, length(TEST2_1), 1, 0, 0,
- "75388B16512776CC5DBA5DA1FD890150B0C6455CB4F58B1952522525" },
- /* 3 */ { TEST3, length(TEST3), 1000000, 0, 0,
- "20794655980C91D8BBB4C1EA97618A4BF03F42581948B2EE4EE7AD67" },
- /* 4 */ { TEST4, length(TEST4), 10, 0, 0,
- "567F69F168CD7844E65259CE658FE7AADFA25216E68ECA0EB7AB8262" },
- /* 5 */ { "", 0, 0, 0x68, 5,
- "E3B048552C3C387BCAB37F6EB06BB79B96A4AEE5FF27F51531A9551C" },
- /* 6 */ { "\x07", 1, 1, 0, 0,
- "00ECD5F138422B8AD74C9799FD826C531BAD2FCABC7450BEE2AA8C2A" },
- /* 7 */ { TEST7_224, length(TEST7_224), 1, 0xA0, 3,
- "1B01DB6CB4A9E43DED1516BEB3DB0B87B6D1EA43187462C608137150" },
- /* 8 */ { TEST8_224, length(TEST8_224), 1, 0, 0,
- "DF90D78AA78821C99B40BA4C966921ACCD8FFB1E98AC388E56191DB1" },
- /* 9 */ { TEST9_224, length(TEST9_224), 1, 0xE0, 3,
- "54BEA6EAB8195A2EB0A7906A4B4A876666300EEFBD1F3B8474F9CD57" },
-
-
-
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-
-
- /* 10 */ { TEST10_224, length(TEST10_224), 1, 0, 0,
- "0B31894EC8937AD9B91BDFBCBA294D9ADEFAA18E09305E9F20D5C3A4" }
- }, SHA224_SEED, { "100966A5B4FDE0B42E2A6C5953D4D7F41BA7CF79FD"
- "2DF431416734BE", "1DCA396B0C417715DEFAAE9641E10A2E99D55A"
- "BCB8A00061EB3BE8BD", "1864E627BDB2319973CD5ED7D68DA71D8B"
- "F0F983D8D9AB32C34ADB34", "A2406481FC1BCAF24DD08E6752E844"
- "709563FB916227FED598EB621F"
- } },
- { "SHA256", SHA256, SHA256HashSize,
- {
- /* 1 */ { TEST1, length(TEST1), 1, 0, 0, "BA7816BF8F01CFEA4141"
- "40DE5DAE2223B00361A396177A9CB410FF61F20015AD" },
- /* 2 */ { TEST2_1, length(TEST2_1), 1, 0, 0, "248D6A61D20638B8"
- "E5C026930C3E6039A33CE45964FF2167F6ECEDD419DB06C1" },
- /* 3 */ { TEST3, length(TEST3), 1000000, 0, 0, "CDC76E5C9914FB92"
- "81A1C7E284D73E67F1809A48A497200E046D39CCC7112CD0" },
- /* 4 */ { TEST4, length(TEST4), 10, 0, 0, "594847328451BDFA"
- "85056225462CC1D867D877FB388DF0CE35F25AB5562BFBB5" },
- /* 5 */ { "", 0, 0, 0x68, 5, "D6D3E02A31A84A8CAA9718ED6C2057BE"
- "09DB45E7823EB5079CE7A573A3760F95" },
- /* 6 */ { "\x19", 1, 1, 0, 0, "68AA2E2EE5DFF96E3355E6C7EE373E3D"
- "6A4E17F75F9518D843709C0C9BC3E3D4" },
- /* 7 */ { TEST7_256, length(TEST7_256), 1, 0x60, 3, "77EC1DC8"
- "9C821FF2A1279089FA091B35B8CD960BCAF7DE01C6A7680756BEB972" },
- /* 8 */ { TEST8_256, length(TEST8_256), 1, 0, 0, "175EE69B02BA"
- "9B58E2B0A5FD13819CEA573F3940A94F825128CF4209BEABB4E8" },
- /* 9 */ { TEST9_256, length(TEST9_256), 1, 0xA0, 3, "3E9AD646"
- "8BBBAD2AC3C2CDC292E018BA5FD70B960CF1679777FCE708FDB066E9" },
- /* 10 */ { TEST10_256, length(TEST10_256), 1, 0, 0, "97DBCA7D"
- "F46D62C8A422C941DD7E835B8AD3361763F7E9B2D95F4F0DA6E1CCBC" },
- }, SHA256_SEED, { "83D28614D49C3ADC1D6FC05DB5F48037C056F8D2A4CE44"
- "EC6457DEA5DD797CD1", "99DBE3127EF2E93DD9322D6A07909EB33B6399"
- "5E529B3F954B8581621BB74D39", "8D4BE295BB64661CA3C7EFD129A2F7"
- "25B33072DBDDE32385B9A87B9AF88EA76F", "40AF5D3F9716B040DF9408"
- "E31536B70FF906EC51B00447CA97D7DD97C12411F4"
- } },
- { "SHA384", SHA384, SHA384HashSize,
- {
- /* 1 */ { TEST1, length(TEST1), 1, 0, 0,
- "CB00753F45A35E8BB5A03D699AC65007272C32AB0EDED163"
- "1A8B605A43FF5BED8086072BA1E7CC2358BAECA134C825A7" },
- /* 2 */ { TEST2_2, length(TEST2_2), 1, 0, 0,
- "09330C33F71147E83D192FC782CD1B4753111B173B3B05D2"
- "2FA08086E3B0F712FCC7C71A557E2DB966C3E9FA91746039" },
- /* 3 */ { TEST3, length(TEST3), 1000000, 0, 0,
- "9D0E1809716474CB086E834E310A4A1CED149E9C00F24852"
- "7972CEC5704C2A5B07B8B3DC38ECC4EBAE97DDD87F3D8985" },
- /* 4 */ { TEST4, length(TEST4), 10, 0, 0,
-
-
-
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-
-
- "2FC64A4F500DDB6828F6A3430B8DD72A368EB7F3A8322A70"
- "BC84275B9C0B3AB00D27A5CC3C2D224AA6B61A0D79FB4596" },
- /* 5 */ { "", 0, 0, 0x10, 5,
- "8D17BE79E32B6718E07D8A603EB84BA0478F7FCFD1BB9399"
- "5F7D1149E09143AC1FFCFC56820E469F3878D957A15A3FE4" },
- /* 6 */ { "\xb9", 1, 1, 0, 0,
- "BC8089A19007C0B14195F4ECC74094FEC64F01F90929282C"
- "2FB392881578208AD466828B1C6C283D2722CF0AD1AB6938" },
- /* 7 */ { TEST7_384, length(TEST7_384), 1, 0xA0, 3,
- "D8C43B38E12E7C42A7C9B810299FD6A770BEF30920F17532"
- "A898DE62C7A07E4293449C0B5FA70109F0783211CFC4BCE3" },
- /* 8 */ { TEST8_384, length(TEST8_384), 1, 0, 0,
- "C9A68443A005812256B8EC76B00516F0DBB74FAB26D66591"
- "3F194B6FFB0E91EA9967566B58109CBC675CC208E4C823F7" },
- /* 9 */ { TEST9_384, length(TEST9_384), 1, 0xE0, 3,
- "5860E8DE91C21578BB4174D227898A98E0B45C4C760F0095"
- "49495614DAEDC0775D92D11D9F8CE9B064EEAC8DAFC3A297" },
- /* 10 */ { TEST10_384, length(TEST10_384), 1, 0, 0,
- "4F440DB1E6EDD2899FA335F09515AA025EE177A79F4B4AAF"
- "38E42B5C4DE660F5DE8FB2A5B2FBD2A3CBFFD20CFF1288C0" }
- }, SHA384_SEED, { "CE44D7D63AE0C91482998CF662A51EC80BF6FC68661A3C"
- "57F87566112BD635A743EA904DEB7D7A42AC808CABE697F38F", "F9C6D2"
- "61881FEE41ACD39E67AA8D0BAD507C7363EB67E2B81F45759F9C0FD7B503"
- "DF1A0B9E80BDE7BC333D75B804197D", "D96512D8C9F4A7A4967A366C01"
- "C6FD97384225B58343A88264847C18E4EF8AB7AEE4765FFBC3E30BD485D3"
- "638A01418F", "0CA76BD0813AF1509E170907A96005938BC985628290B2"
- "5FEF73CF6FAD68DDBA0AC8920C94E0541607B0915A7B4457F7"
- } },
- { "SHA512", SHA512, SHA512HashSize,
- {
- /* 1 */ { TEST1, length(TEST1), 1, 0, 0,
- "DDAF35A193617ABACC417349AE20413112E6FA4E89A97EA2"
- "0A9EEEE64B55D39A2192992A274FC1A836BA3C23A3FEEBBD"
- "454D4423643CE80E2A9AC94FA54CA49F" },
- /* 2 */ { TEST2_2, length(TEST2_2), 1, 0, 0,
- "8E959B75DAE313DA8CF4F72814FC143F8F7779C6EB9F7FA1"
- "7299AEADB6889018501D289E4900F7E4331B99DEC4B5433A"
- "C7D329EEB6DD26545E96E55B874BE909" },
- /* 3 */ { TEST3, length(TEST3), 1000000, 0, 0,
- "E718483D0CE769644E2E42C7BC15B4638E1F98B13B204428"
- "5632A803AFA973EBDE0FF244877EA60A4CB0432CE577C31B"
- "EB009C5C2C49AA2E4EADB217AD8CC09B" },
- /* 4 */ { TEST4, length(TEST4), 10, 0, 0,
- "89D05BA632C699C31231DED4FFC127D5A894DAD412C0E024"
- "DB872D1ABD2BA8141A0F85072A9BE1E2AA04CF33C765CB51"
- "0813A39CD5A84C4ACAA64D3F3FB7BAE9" },
- /* 5 */ { "", 0, 0, 0xB0, 5,
- "D4EE29A9E90985446B913CF1D1376C836F4BE2C1CF3CADA0"
-
-
-
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-
-
- "720A6BF4857D886A7ECB3C4E4C0FA8C7F95214E41DC1B0D2"
- "1B22A84CC03BF8CE4845F34DD5BDBAD4" },
- /* 6 */ { "\xD0", 1, 1, 0, 0,
- "9992202938E882E73E20F6B69E68A0A7149090423D93C81B"
- "AB3F21678D4ACEEEE50E4E8CAFADA4C85A54EA8306826C4A"
- "D6E74CECE9631BFA8A549B4AB3FBBA15" },
- /* 7 */ { TEST7_512, length(TEST7_512), 1, 0x80, 3,
- "ED8DC78E8B01B69750053DBB7A0A9EDA0FB9E9D292B1ED71"
- "5E80A7FE290A4E16664FD913E85854400C5AF05E6DAD316B"
- "7359B43E64F8BEC3C1F237119986BBB6" },
- /* 8 */ { TEST8_512, length(TEST8_512), 1, 0, 0,
- "CB0B67A4B8712CD73C9AABC0B199E9269B20844AFB75ACBD"
- "D1C153C9828924C3DDEDAAFE669C5FDD0BC66F630F677398"
- "8213EB1B16F517AD0DE4B2F0C95C90F8" },
- /* 9 */ { TEST9_512, length(TEST9_512), 1, 0x80, 3,
- "32BA76FC30EAA0208AEB50FFB5AF1864FDBF17902A4DC0A6"
- "82C61FCEA6D92B783267B21080301837F59DE79C6B337DB2"
- "526F8A0A510E5E53CAFED4355FE7C2F1" },
- /* 10 */ { TEST10_512, length(TEST10_512), 1, 0, 0,
- "C665BEFB36DA189D78822D10528CBF3B12B3EEF726039909"
- "C1A16A270D48719377966B957A878E720584779A62825C18"
- "DA26415E49A7176A894E7510FD1451F5" }
- }, SHA512_SEED, { "2FBB1E7E00F746BA514FBC8C421F36792EC0E11FF5EFC3"
- "78E1AB0C079AA5F0F66A1E3EDBAEB4F9984BE14437123038A452004A5576"
- "8C1FD8EED49E4A21BEDCD0", "25CBE5A4F2C7B1D7EF07011705D50C62C5"
- "000594243EAFD1241FC9F3D22B58184AE2FEE38E171CF8129E29459C9BC2"
- "EF461AF5708887315F15419D8D17FE7949", "5B8B1F2687555CE2D7182B"
- "92E5C3F6C36547DA1C13DBB9EA4F73EA4CBBAF89411527906D35B1B06C1B"
- "6A8007D05EC66DF0A406066829EAB618BDE3976515AAFC", "46E36B007D"
- "19876CDB0B29AD074FE3C08CDD174D42169D6ABE5A1414B6E79707DF5877"
- "6A98091CF431854147BB6D3C66D43BFBC108FD715BDE6AA127C2B0E79F"
- }
- }
-};
-
-/* Test arrays for HMAC. */
-struct hmachash {
- const char *keyarray[5];
- int keylength[5];
- const char *dataarray[5];
- int datalength[5];
- const char *resultarray[5];
- int resultlength[5];
-} hmachashes[HMACTESTCOUNT] = {
- { /* 1 */ {
- "\x0b\x0b\x0b\x0b\x0b\x0b\x0b\x0b\x0b\x0b\x0b\x0b\x0b\x0b\x0b"
- "\x0b\x0b\x0b\x0b\x0b"
- }, { 20 }, {
-
-
-
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-
-
- "\x48\x69\x20\x54\x68\x65\x72\x65" /* "Hi There" */
- }, { 8 }, {
- /* HMAC-SHA-1 */
- "B617318655057264E28BC0B6FB378C8EF146BE00",
- /* HMAC-SHA-224 */
- "896FB1128ABBDF196832107CD49DF33F47B4B1169912BA4F53684B22",
- /* HMAC-SHA-256 */
- "B0344C61D8DB38535CA8AFCEAF0BF12B881DC200C9833DA726E9376C2E32"
- "CFF7",
- /* HMAC-SHA-384 */
- "AFD03944D84895626B0825F4AB46907F15F9DADBE4101EC682AA034C7CEB"
- "C59CFAEA9EA9076EDE7F4AF152E8B2FA9CB6",
- /* HMAC-SHA-512 */
- "87AA7CDEA5EF619D4FF0B4241A1D6CB02379F4E2CE4EC2787AD0B30545E1"
- "7CDEDAA833B7D6B8A702038B274EAEA3F4E4BE9D914EEB61F1702E696C20"
- "3A126854"
- }, { SHA1HashSize, SHA224HashSize, SHA256HashSize,
- SHA384HashSize, SHA512HashSize }
- },
- { /* 2 */ {
- "\x4a\x65\x66\x65" /* "Jefe" */
- }, { 4 }, {
- "\x77\x68\x61\x74\x20\x64\x6f\x20\x79\x61\x20\x77\x61\x6e\x74"
- "\x20\x66\x6f\x72\x20\x6e\x6f\x74\x68\x69\x6e\x67\x3f"
- /* "what do ya want for nothing?" */
- }, { 28 }, {
- /* HMAC-SHA-1 */
- "EFFCDF6AE5EB2FA2D27416D5F184DF9C259A7C79",
- /* HMAC-SHA-224 */
- "A30E01098BC6DBBF45690F3A7E9E6D0F8BBEA2A39E6148008FD05E44",
- /* HMAC-SHA-256 */
- "5BDCC146BF60754E6A042426089575C75A003F089D2739839DEC58B964EC"
- "3843",
- /* HMAC-SHA-384 */
- "AF45D2E376484031617F78D2B58A6B1B9C7EF464F5A01B47E42EC3736322"
- "445E8E2240CA5E69E2C78B3239ECFAB21649",
- /* HMAC-SHA-512 */
- "164B7A7BFCF819E2E395FBE73B56E0A387BD64222E831FD610270CD7EA25"
- "05549758BF75C05A994A6D034F65F8F0E6FDCAEAB1A34D4A6B4B636E070A"
- "38BCE737"
- }, { SHA1HashSize, SHA224HashSize, SHA256HashSize,
- SHA384HashSize, SHA512HashSize }
- },
- { /* 3 */
- {
- "\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa"
- "\xaa\xaa\xaa\xaa\xaa"
- }, { 20 }, {
-
-
-
-Eastlake 3rd & Hansen Informational [Page 87]
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-RFC 4634 SHAs and HMAC-SHAs July 2006
-
-
- "\xdd\xdd\xdd\xdd\xdd\xdd\xdd\xdd\xdd\xdd\xdd\xdd\xdd\xdd\xdd"
- "\xdd\xdd\xdd\xdd\xdd\xdd\xdd\xdd\xdd\xdd\xdd\xdd\xdd\xdd\xdd"
- "\xdd\xdd\xdd\xdd\xdd\xdd\xdd\xdd\xdd\xdd\xdd\xdd\xdd\xdd\xdd"
- "\xdd\xdd\xdd\xdd\xdd"
- }, { 50 }, {
- /* HMAC-SHA-1 */
- "125D7342B9AC11CD91A39AF48AA17B4F63F175D3",
- /* HMAC-SHA-224 */
- "7FB3CB3588C6C1F6FFA9694D7D6AD2649365B0C1F65D69D1EC8333EA",
- /* HMAC-SHA-256 */
- "773EA91E36800E46854DB8EBD09181A72959098B3EF8C122D9635514CED5"
- "65FE",
- /* HMAC-SHA-384 */
- "88062608D3E6AD8A0AA2ACE014C8A86F0AA635D947AC9FEBE83EF4E55966"
- "144B2A5AB39DC13814B94E3AB6E101A34F27",
- /* HMAC-SHA-512 */
- "FA73B0089D56A284EFB0F0756C890BE9B1B5DBDD8EE81A3655F83E33B227"
- "9D39BF3E848279A722C806B485A47E67C807B946A337BEE8942674278859"
- "E13292FB"
- }, { SHA1HashSize, SHA224HashSize, SHA256HashSize,
- SHA384HashSize, SHA512HashSize }
- },
- { /* 4 */ {
- "\x01\x02\x03\x04\x05\x06\x07\x08\x09\x0a\x0b\x0c\x0d\x0e\x0f"
- "\x10\x11\x12\x13\x14\x15\x16\x17\x18\x19"
- }, { 25 }, {
- "\xcd\xcd\xcd\xcd\xcd\xcd\xcd\xcd\xcd\xcd\xcd\xcd\xcd\xcd\xcd"
- "\xcd\xcd\xcd\xcd\xcd\xcd\xcd\xcd\xcd\xcd\xcd\xcd\xcd\xcd\xcd"
- "\xcd\xcd\xcd\xcd\xcd\xcd\xcd\xcd\xcd\xcd\xcd\xcd\xcd\xcd\xcd"
- "\xcd\xcd\xcd\xcd\xcd"
- }, { 50 }, {
- /* HMAC-SHA-1 */
- "4C9007F4026250C6BC8414F9BF50C86C2D7235DA",
- /* HMAC-SHA-224 */
- "6C11506874013CAC6A2ABC1BB382627CEC6A90D86EFC012DE7AFEC5A",
- /* HMAC-SHA-256 */
- "82558A389A443C0EA4CC819899F2083A85F0FAA3E578F8077A2E3FF46729"
- "665B",
- /* HMAC-SHA-384 */
- "3E8A69B7783C25851933AB6290AF6CA77A9981480850009CC5577C6E1F57"
- "3B4E6801DD23C4A7D679CCF8A386C674CFFB",
- /* HMAC-SHA-512 */
- "B0BA465637458C6990E5A8C5F61D4AF7E576D97FF94B872DE76F8050361E"
- "E3DBA91CA5C11AA25EB4D679275CC5788063A5F19741120C4F2DE2ADEBEB"
- "10A298DD"
- }, { SHA1HashSize, SHA224HashSize, SHA256HashSize,
- SHA384HashSize, SHA512HashSize }
- },
-
-
-
-Eastlake 3rd & Hansen Informational [Page 88]
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-RFC 4634 SHAs and HMAC-SHAs July 2006
-
-
- { /* 5 */ {
- "\x0c\x0c\x0c\x0c\x0c\x0c\x0c\x0c\x0c\x0c\x0c\x0c\x0c\x0c\x0c"
- "\x0c\x0c\x0c\x0c\x0c"
- }, { 20 }, {
- "Test With Truncation"
- }, { 20 }, {
- /* HMAC-SHA-1 */
- "4C1A03424B55E07FE7F27BE1",
- /* HMAC-SHA-224 */
- "0E2AEA68A90C8D37C988BCDB9FCA6FA8",
- /* HMAC-SHA-256 */
- "A3B6167473100EE06E0C796C2955552B",
- /* HMAC-SHA-384 */
- "3ABF34C3503B2A23A46EFC619BAEF897",
- /* HMAC-SHA-512 */
- "415FAD6271580A531D4179BC891D87A6"
- }, { 12, 16, 16, 16, 16 }
- },
- { /* 6 */ {
- "\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa"
- "\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa"
- "\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa"
- "\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa"
- "\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa"
- "\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa"
- "\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa"
- "\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa"
- "\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa"
- }, { 80, 131 }, {
- "Test Using Larger Than Block-Size Key - Hash Key First"
- }, { 54 }, {
- /* HMAC-SHA-1 */
- "AA4AE5E15272D00E95705637CE8A3B55ED402112",
- /* HMAC-SHA-224 */
- "95E9A0DB962095ADAEBE9B2D6F0DBCE2D499F112F2D2B7273FA6870E",
- /* HMAC-SHA-256 */
- "60E431591EE0B67F0D8A26AACBF5B77F8E0BC6213728C5140546040F0EE3"
- "7F54",
- /* HMAC-SHA-384 */
- "4ECE084485813E9088D2C63A041BC5B44F9EF1012A2B588F3CD11F05033A"
- "C4C60C2EF6AB4030FE8296248DF163F44952",
- /* HMAC-SHA-512 */
- "80B24263C7C1A3EBB71493C1DD7BE8B49B46D1F41B4AEEC1121B013783F8"
- "F3526B56D037E05F2598BD0FD2215D6A1E5295E64F73F63F0AEC8B915A98"
- "5D786598"
- }, { SHA1HashSize, SHA224HashSize, SHA256HashSize,
- SHA384HashSize, SHA512HashSize }
- },
-
-
-
-Eastlake 3rd & Hansen Informational [Page 89]
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-
-
- { /* 7 */ {
- "\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa"
- "\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa"
- "\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa"
- "\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa"
- "\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa"
- "\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa"
- "\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa"
- "\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa"
- "\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa\xaa"
- }, { 80, 131 }, {
- "Test Using Larger Than Block-Size Key and "
- "Larger Than One Block-Size Data",
- "\x54\x68\x69\x73\x20\x69\x73\x20\x61\x20\x74\x65\x73\x74\x20"
- "\x75\x73\x69\x6e\x67\x20\x61\x20\x6c\x61\x72\x67\x65\x72\x20"
- "\x74\x68\x61\x6e\x20\x62\x6c\x6f\x63\x6b\x2d\x73\x69\x7a\x65"
- "\x20\x6b\x65\x79\x20\x61\x6e\x64\x20\x61\x20\x6c\x61\x72\x67"
- "\x65\x72\x20\x74\x68\x61\x6e\x20\x62\x6c\x6f\x63\x6b\x2d\x73"
- "\x69\x7a\x65\x20\x64\x61\x74\x61\x2e\x20\x54\x68\x65\x20\x6b"
- "\x65\x79\x20\x6e\x65\x65\x64\x73\x20\x74\x6f\x20\x62\x65\x20"
- "\x68\x61\x73\x68\x65\x64\x20\x62\x65\x66\x6f\x72\x65\x20\x62"
- "\x65\x69\x6e\x67\x20\x75\x73\x65\x64\x20\x62\x79\x20\x74\x68"
- "\x65\x20\x48\x4d\x41\x43\x20\x61\x6c\x67\x6f\x72\x69\x74\x68"
- "\x6d\x2e"
- /* "This is a test using a larger than block-size key and a "
- "larger than block-size data. The key needs to be hashed "
- "before being used by the HMAC algorithm." */
- }, { 73, 152 }, {
- /* HMAC-SHA-1 */
- "E8E99D0F45237D786D6BBAA7965C7808BBFF1A91",
- /* HMAC-SHA-224 */
- "3A854166AC5D9F023F54D517D0B39DBD946770DB9C2B95C9F6F565D1",
- /* HMAC-SHA-256 */
- "9B09FFA71B942FCB27635FBCD5B0E944BFDC63644F0713938A7F51535C3A"
- "35E2",
- /* HMAC-SHA-384 */
- "6617178E941F020D351E2F254E8FD32C602420FEB0B8FB9ADCCEBB82461E"
- "99C5A678CC31E799176D3860E6110C46523E",
- /* HMAC-SHA-512 */
- "E37B6A775DC87DBAA4DFA9F96E5E3FFDDEBD71F8867289865DF5A32D20CD"
- "C944B6022CAC3C4982B10D5EEB55C3E4DE15134676FB6DE0446065C97440"
- "FA8C6A58"
- }, { SHA1HashSize, SHA224HashSize, SHA256HashSize,
- SHA384HashSize, SHA512HashSize }
- }
-};
-
-/*
-
-
-
-Eastlake 3rd & Hansen Informational [Page 90]
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-RFC 4634 SHAs and HMAC-SHAs July 2006
-
-
- * Check the hash value against the expected string, expressed in hex
- */
-static const char hexdigits[] = "0123456789ABCDEF";
-int checkmatch(const unsigned char *hashvalue,
- const char *hexstr, int hashsize)
-{
- int i;
- for (i = 0; i < hashsize; ++i) {
- if (*hexstr++ != hexdigits[(hashvalue[i] >> 4) & 0xF])
- return 0;
- if (*hexstr++ != hexdigits[hashvalue[i] & 0xF]) return 0;
- }
- return 1;
-}
-
-/*
- * Print the string, converting non-printable characters to "."
- */
-void printstr(const char *str, int len)
-{
- for ( ; len-- > 0; str++)
- putchar(isprint((unsigned char)*str) ? *str : '.');
-}
-
-/*
- * Print the string, converting non-printable characters to hex "## ".
- */
-void printxstr(const char *str, int len)
-{
- for ( ; len-- > 0; str++)
- printf("%c%c ", hexdigits[(*str >> 4) & 0xF],
- hexdigits[*str & 0xF]);
-}
-
-/*
- * Print a usage message.
- */
-void usage(const char *argv0)
-{
- fprintf(stderr,
- "Usage:\n"
- "Common options: [-h hash] [-w|-x] [-H]\n"
- "Standard tests:\n"
- "\t%s [-m] [-l loopcount] [-t test#] [-e]\n"
- "\t\t[-r randomseed] [-R randomloop-count] "
- "[-p] [-P|-X]\n"
- "Hash a string:\n"
- "\t%s [-S expectedresult] -s hashstr [-k key]\n"
-
-
-
-Eastlake 3rd & Hansen Informational [Page 91]
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-RFC 4634 SHAs and HMAC-SHAs July 2006
-
-
- "Hash a file:\n"
- "\t%s [-S expectedresult] -f file [-k key]\n"
- "Hash a file, ignoring whitespace:\n"
- "\t%s [-S expectedresult] -F file [-k key]\n"
- "Additional bits to add in: [-B bitcount -b bits]\n"
- "-h\thash to test: "
- "0|SHA1, 1|SHA224, 2|SHA256, 3|SHA384, 4|SHA512\n"
- "-m\tperform hmac test\n"
- "-k\tkey for hmac test\n"
- "-t\ttest case to run, 1-10\n"
- "-l\thow many times to run the test\n"
- "-e\ttest error returns\n"
- "-p\tdo not print results\n"
- "-P\tdo not print PASSED/FAILED\n"
- "-X\tprint FAILED, but not PASSED\n"
- "-r\tseed for random test\n"
- "-R\thow many times to run random test\n"
- "-s\tstring to hash\n"
- "-S\texpected result of hashed string, in hex\n"
- "-w\toutput hash in raw format\n"
- "-x\toutput hash in hex format\n"
- "-B\t# extra bits to add in after string or file input\n"
- "-b\textra bits to add (high order bits of #, 0# or 0x#)\n"
- "-H\tinput hashstr or randomseed is in hex\n"
- , argv0, argv0, argv0, argv0);
- exit(1);
-}
-
-/*
- * Print the results and PASS/FAIL.
- */
-void printResult(uint8_t *Message_Digest, int hashsize,
- const char *hashname, const char *testtype, const char *testname,
- const char *resultarray, int printResults, int printPassFail)
-{
- int i, k;
- if (printResults == PRINTTEXT) {
- putchar('\t');
- for (i = 0; i < hashsize ; ++i) {
- putchar(hexdigits[(Message_Digest[i] >> 4) & 0xF]);
- putchar(hexdigits[Message_Digest[i] & 0xF]);
- putchar(' ');
- }
- putchar('\n');
- } else if (printResults == PRINTRAW) {
- fwrite(Message_Digest, 1, hashsize, stdout);
- } else if (printResults == PRINTHEX) {
- for (i = 0; i < hashsize ; ++i) {
-
-
-
-Eastlake 3rd & Hansen Informational [Page 92]
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-RFC 4634 SHAs and HMAC-SHAs July 2006
-
-
- putchar(hexdigits[(Message_Digest[i] >> 4) & 0xF]);
- putchar(hexdigits[Message_Digest[i] & 0xF]);
- }
- putchar('\n');
- }
-
- if (printResults && resultarray) {
- printf(" Should match:\n\t");
- for (i = 0, k = 0; i < hashsize; i++, k += 2) {
- putchar(resultarray[k]);
- putchar(resultarray[k+1]);
- putchar(' ');
- }
- putchar('\n');
- }
-
- if (printPassFail && resultarray) {
- int ret = checkmatch(Message_Digest, resultarray, hashsize);
- if ((printPassFail == PRINTPASSFAIL) || !ret)
- printf("%s %s %s: %s\n", hashname, testtype, testname,
- ret ? "PASSED" : "FAILED");
- }
-}
-
-/*
- * Exercise a hash series of functions. The input is the testarray,
- * repeated repeatcount times, followed by the extrabits. If the
- * result is known, it is in resultarray in uppercase hex.
- */
-int hash(int testno, int loopno, int hashno,
- const char *testarray, int length, long repeatcount,
- int numberExtrabits, int extrabits, const unsigned char *keyarray,
- int keylen, const char *resultarray, int hashsize, int printResults,
- int printPassFail)
-{
- USHAContext sha;
- HMACContext hmac;
- int err, i;
- uint8_t Message_Digest[USHAMaxHashSize];
- char buf[20];
-
- if (printResults == PRINTTEXT) {
- printf("\nTest %d: Iteration %d, Repeat %ld\n\t'", testno+1,
- loopno, repeatcount);
- printstr(testarray, length);
- printf("'\n\t'");
- printxstr(testarray, length);
- printf("'\n");
-
-
-
-Eastlake 3rd & Hansen Informational [Page 93]
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-RFC 4634 SHAs and HMAC-SHAs July 2006
-
-
- printf(" Length=%d bytes (%d bits), ", length, length * 8);
- printf("ExtraBits %d: %2.2x\n", numberExtrabits, extrabits);
- }
-
- memset(&sha, '\343', sizeof(sha)); /* force bad data into struct */
- memset(&hmac, '\343', sizeof(hmac));
- err = keyarray ? hmacReset(&hmac, hashes[hashno].whichSha,
- keyarray, keylen) :
- USHAReset(&sha, hashes[hashno].whichSha);
- if (err != shaSuccess) {
- fprintf(stderr, "hash(): %sReset Error %d.\n",
- keyarray ? "hmac" : "sha", err);
- return err;
- }
-
- for (i = 0; i < repeatcount; ++i) {
- err = keyarray ? hmacInput(&hmac, (const uint8_t *) testarray,
- length) :
- USHAInput(&sha, (const uint8_t *) testarray,
- length);
- if (err != shaSuccess) {
- fprintf(stderr, "hash(): %sInput Error %d.\n",
- keyarray ? "hmac" : "sha", err);
- return err;
- }
- }
-
- if (numberExtrabits > 0) {
- err = keyarray ? hmacFinalBits(&hmac, (uint8_t) extrabits,
- numberExtrabits) :
- USHAFinalBits(&sha, (uint8_t) extrabits,
- numberExtrabits);
- if (err != shaSuccess) {
- fprintf(stderr, "hash(): %sFinalBits Error %d.\n",
- keyarray ? "hmac" : "sha", err);
- return err;
- }
- }
-
- err = keyarray ? hmacResult(&hmac, Message_Digest) :
- USHAResult(&sha, Message_Digest);
- if (err != shaSuccess) {
- fprintf(stderr, "hash(): %s Result Error %d, could not "
- "compute message digest.\n", keyarray ? "hmac" : "sha", err);
- return err;
- }
-
- sprintf(buf, "%d", testno+1);
-
-
-
-Eastlake 3rd & Hansen Informational [Page 94]
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-RFC 4634 SHAs and HMAC-SHAs July 2006
-
-
- printResult(Message_Digest, hashsize, hashes[hashno].name,
- keyarray ? "hmac standard test" : "sha standard test", buf,
- resultarray, printResults, printPassFail);
-
- return err;
-}
-
-/*
- * Exercise a hash series of functions. The input is a filename.
- * If the result is known, it is in resultarray in uppercase hex.
- */
-int hashfile(int hashno, const char *hashfilename, int bits,
- int bitcount, int skipSpaces, const unsigned char *keyarray,
- int keylen, const char *resultarray, int hashsize,
- int printResults, int printPassFail)
-{
- USHAContext sha;
- HMACContext hmac;
- int err, nread, c;
- unsigned char buf[4096];
- uint8_t Message_Digest[USHAMaxHashSize];
- unsigned char cc;
- FILE *hashfp = (strcmp(hashfilename, "-") == 0) ? stdin :
- fopen(hashfilename, "r");
-
- if (!hashfp) {
- fprintf(stderr, "cannot open file '%s'\n", hashfilename);
- return shaStateError;
- }
-
- memset(&sha, '\343', sizeof(sha)); /* force bad data into struct */
- memset(&hmac, '\343', sizeof(hmac));
- err = keyarray ? hmacReset(&hmac, hashes[hashno].whichSha,
- keyarray, keylen) :
- USHAReset(&sha, hashes[hashno].whichSha);
-
- if (err != shaSuccess) {
- fprintf(stderr, "hashfile(): %sReset Error %d.\n",
- keyarray ? "hmac" : "sha", err);
- return err;
- }
-
- if (skipSpaces)
- while ((c = getc(hashfp)) != EOF) {
- if (!isspace(c)) {
- cc = (unsigned char)c;
- err = keyarray ? hmacInput(&hmac, &cc, 1) :
- USHAInput(&sha, &cc, 1);
-
-
-
-Eastlake 3rd & Hansen Informational [Page 95]
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-RFC 4634 SHAs and HMAC-SHAs July 2006
-
-
- if (err != shaSuccess) {
- fprintf(stderr, "hashfile(): %sInput Error %d.\n",
- keyarray ? "hmac" : "sha", err);
- if (hashfp != stdin) fclose(hashfp);
- return err;
- }
- }
- }
- else
- while ((nread = fread(buf, 1, sizeof(buf), hashfp)) > 0) {
- err = keyarray ? hmacInput(&hmac, buf, nread) :
- USHAInput(&sha, buf, nread);
- if (err != shaSuccess) {
- fprintf(stderr, "hashfile(): %s Error %d.\n",
- keyarray ? "hmacInput" : "shaInput", err);
- if (hashfp != stdin) fclose(hashfp);
- return err;
- }
- }
-
- if (bitcount > 0)
- err = keyarray ? hmacFinalBits(&hmac, bits, bitcount) :
- USHAFinalBits(&sha, bits, bitcount);
- if (err != shaSuccess) {
- fprintf(stderr, "hashfile(): %s Error %d.\n",
- keyarray ? "hmacResult" : "shaResult", err);
- if (hashfp != stdin) fclose(hashfp);
- return err;
- }
-
- err = keyarray ? hmacResult(&hmac, Message_Digest) :
- USHAResult(&sha, Message_Digest);
- if (err != shaSuccess) {
- fprintf(stderr, "hashfile(): %s Error %d.\n",
- keyarray ? "hmacResult" : "shaResult", err);
- if (hashfp != stdin) fclose(hashfp);
- return err;
- }
-
- printResult(Message_Digest, hashsize, hashes[hashno].name, "file",
- hashfilename, resultarray, printResults, printPassFail);
-
- if (hashfp != stdin) fclose(hashfp);
- return err;
-}
-
-/*
- * Exercise a hash series of functions through multiple permutations.
-
-
-
-Eastlake 3rd & Hansen Informational [Page 96]
-\f
-RFC 4634 SHAs and HMAC-SHAs July 2006
-
-
- * The input is an initial seed. That seed is replicated 3 times.
- * For 1000 rounds, the previous three results are used as the input.
- * This result is then checked, and used to seed the next cycle.
- * If the result is known, it is in resultarrays in uppercase hex.
- */
-void randomtest(int hashno, const char *seed, int hashsize,
- const char **resultarrays, int randomcount,
- int printResults, int printPassFail)
-{
- int i, j; char buf[20];
- unsigned char SEED[USHAMaxHashSize], MD[1003][USHAMaxHashSize];
-
- /* INPUT: Seed - A random seed n bits long */
- memcpy(SEED, seed, hashsize);
- if (printResults == PRINTTEXT) {
- printf("%s random test seed= '", hashes[hashno].name);
- printxstr(seed, hashsize);
- printf("'\n");
- }
-
- for (j = 0; j < randomcount; j++) {
- /* MD0 = MD1 = MD2 = Seed; */
- memcpy(MD[0], SEED, hashsize);
- memcpy(MD[1], SEED, hashsize);
- memcpy(MD[2], SEED, hashsize);
- for (i=3; i<1003; i++) {
- /* Mi = MDi-3 || MDi-2 || MDi-1; */
- USHAContext Mi;
- memset(&Mi, '\343', sizeof(Mi)); /* force bad data into struct */
- USHAReset(&Mi, hashes[hashno].whichSha);
- USHAInput(&Mi, MD[i-3], hashsize);
- USHAInput(&Mi, MD[i-2], hashsize);
- USHAInput(&Mi, MD[i-1], hashsize);
- /* MDi = SHA(Mi); */
- USHAResult(&Mi, MD[i]);
- }
-
- /* MDj = Seed = MDi; */
- memcpy(SEED, MD[i-1], hashsize);
-
- /* OUTPUT: MDj */
- sprintf(buf, "%d", j);
- printResult(SEED, hashsize, hashes[hashno].name, "random test",
- buf, resultarrays ? resultarrays[j] : 0, printResults,
- (j < RANDOMCOUNT) ? printPassFail : 0);
- }
-}
-
-
-
-
-Eastlake 3rd & Hansen Informational [Page 97]
-\f
-RFC 4634 SHAs and HMAC-SHAs July 2006
-
-
-/*
- * Look up a hash name.
- */
-int findhash(const char *argv0, const char *opt)
-{
- int i;
- const char *names[HASHCOUNT][2] = {
- { "0", "sha1" }, { "1", "sha224" }, { "2", "sha256" },
- { "3", "sha384" }, { "4", "sha512" }
- };
-
- for (i = 0; i < HASHCOUNT; i++)
- if ((strcmp(opt, names[i][0]) == 0) ||
- (scasecmp(opt, names[i][1]) == 0))
- return i;
-
- fprintf(stderr, "%s: Unknown hash name: '%s'\n", argv0, opt);
- usage(argv0);
- return 0;
-}
-
-/*
- * Run some tests that should invoke errors.
- */
-void testErrors(int hashnolow, int hashnohigh, int printResults,
- int printPassFail)
-{
- USHAContext usha;
- uint8_t Message_Digest[USHAMaxHashSize];
- int hashno, err;
-
- for (hashno = hashnolow; hashno <= hashnohigh; hashno++) {
- memset(&usha, '\343', sizeof(usha)); /* force bad data */
- USHAReset(&usha, hashno);
- USHAResult(&usha, Message_Digest);
- err = USHAInput(&usha, (const unsigned char *)"foo", 3);
- if (printResults == PRINTTEXT)
- printf ("\nError %d. Should be %d.\n", err, shaStateError);
- if ((printPassFail == PRINTPASSFAIL) ||
- ((printPassFail == PRINTFAIL) && (err != shaStateError)))
- printf("%s se: %s\n", hashes[hashno].name,
- (err == shaStateError) ? "PASSED" : "FAILED");
-
- err = USHAFinalBits(&usha, 0x80, 3);
- if (printResults == PRINTTEXT)
- printf ("\nError %d. Should be %d.\n", err, shaStateError);
- if ((printPassFail == PRINTPASSFAIL) ||
- ((printPassFail == PRINTFAIL) && (err != shaStateError)))
-
-
-
-Eastlake 3rd & Hansen Informational [Page 98]
-\f
-RFC 4634 SHAs and HMAC-SHAs July 2006
-
-
- printf("%s se: %s\n", hashes[hashno].name,
- (err == shaStateError) ? "PASSED" : "FAILED");
-
- err = USHAReset(0, hashes[hashno].whichSha);
- if (printResults == PRINTTEXT)
- printf("\nError %d. Should be %d.\n", err, shaNull);
- if ((printPassFail == PRINTPASSFAIL) ||
- ((printPassFail == PRINTFAIL) && (err != shaNull)))
- printf("%s usha null: %s\n", hashes[hashno].name,
- (err == shaNull) ? "PASSED" : "FAILED");
-
- switch (hashno) {
- case SHA1: err = SHA1Reset(0); break;
- case SHA224: err = SHA224Reset(0); break;
- case SHA256: err = SHA256Reset(0); break;
- case SHA384: err = SHA384Reset(0); break;
- case SHA512: err = SHA512Reset(0); break;
- }
- if (printResults == PRINTTEXT)
- printf("\nError %d. Should be %d.\n", err, shaNull);
- if ((printPassFail == PRINTPASSFAIL) ||
- ((printPassFail == PRINTFAIL) && (err != shaNull)))
- printf("%s sha null: %s\n", hashes[hashno].name,
- (err == shaNull) ? "PASSED" : "FAILED");
- }
-}
-
-/* replace a hex string in place with its value */
-int unhexStr(char *hexstr)
-{
- char *o = hexstr;
- int len = 0, nibble1 = 0, nibble2 = 0;
- if (!hexstr) return 0;
- for ( ; *hexstr; hexstr++) {
- if (isalpha((int)(unsigned char)(*hexstr))) {
- nibble1 = tolower(*hexstr) - 'a' + 10;
- } else if (isdigit((int)(unsigned char)(*hexstr))) {
- nibble1 = *hexstr - '0';
- } else {
- printf("\nError: bad hex character '%c'\n", *hexstr);
- }
- if (!*++hexstr) break;
- if (isalpha((int)(unsigned char)(*hexstr))) {
- nibble2 = tolower(*hexstr) - 'a' + 10;
- } else if (isdigit((int)(unsigned char)(*hexstr))) {
- nibble2 = *hexstr - '0';
- } else {
- printf("\nError: bad hex character '%c'\n", *hexstr);
-
-
-
-Eastlake 3rd & Hansen Informational [Page 99]
-\f
-RFC 4634 SHAs and HMAC-SHAs July 2006
-
-
- }
- *o++ = (char)((nibble1 << 4) | nibble2);
- len++;
- }
- return len;
-}
-
-int main(int argc, char **argv)
-{
- int i, err;
- int loopno, loopnohigh = 1;
- int hashno, hashnolow = 0, hashnohigh = HASHCOUNT - 1;
- int testno, testnolow = 0, testnohigh;
- int ntestnohigh = 0;
- int printResults = PRINTTEXT;
- int printPassFail = 1;
- int checkErrors = 0;
- char *hashstr = 0;
- int hashlen = 0;
- const char *resultstr = 0;
- char *randomseedstr = 0;
- int runHmacTests = 0;
- char *hmacKey = 0;
- int hmaclen = 0;
- int randomcount = RANDOMCOUNT;
- const char *hashfilename = 0;
- const char *hashFilename = 0;
- int extrabits = 0, numberExtrabits = 0;
- int strIsHex = 0;
-
- while ((i = xgetopt(argc, argv, "b:B:ef:F:h:Hk:l:mpPr:R:s:S:t:wxX"))
- != -1)
- switch (i) {
- case 'b': extrabits = strtol(xoptarg, 0, 0); break;
- case 'B': numberExtrabits = atoi(xoptarg); break;
- case 'e': checkErrors = 1; break;
- case 'f': hashfilename = xoptarg; break;
- case 'F': hashFilename = xoptarg; break;
- case 'h': hashnolow = hashnohigh = findhash(argv[0], xoptarg);
- break;
- case 'H': strIsHex = 1; break;
- case 'k': hmacKey = xoptarg; hmaclen = strlen(xoptarg); break;
- case 'l': loopnohigh = atoi(xoptarg); break;
- case 'm': runHmacTests = 1; break;
- case 'P': printPassFail = 0; break;
- case 'p': printResults = PRINTNONE; break;
- case 'R': randomcount = atoi(xoptarg); break;
- case 'r': randomseedstr = xoptarg; break;
-
-
-
-Eastlake 3rd & Hansen Informational [Page 100]
-\f
-RFC 4634 SHAs and HMAC-SHAs July 2006
-
-
- case 's': hashstr = xoptarg; hashlen = strlen(hashstr); break;
- case 'S': resultstr = xoptarg; break;
- case 't': testnolow = ntestnohigh = atoi(xoptarg) - 1; break;
- case 'w': printResults = PRINTRAW; break;
- case 'x': printResults = PRINTHEX; break;
- case 'X': printPassFail = 2; break;
- default: usage(argv[0]);
- }
-
- if (strIsHex) {
- hashlen = unhexStr(hashstr);
- unhexStr(randomseedstr);
- hmaclen = unhexStr(hmacKey);
- }
- testnohigh = (ntestnohigh != 0) ? ntestnohigh:
- runHmacTests ? (HMACTESTCOUNT-1) : (TESTCOUNT-1);
- if ((testnolow < 0) ||
- (testnohigh >= (runHmacTests ? HMACTESTCOUNT : TESTCOUNT)) ||
- (hashnolow < 0) || (hashnohigh >= HASHCOUNT) ||
- (hashstr && (testnolow == testnohigh)) ||
- (randomcount < 0) ||
- (resultstr && (!hashstr && !hashfilename && !hashFilename)) ||
- ((runHmacTests || hmacKey) && randomseedstr) ||
- (hashfilename && hashFilename))
- usage(argv[0]);
-
- /*
- * Perform SHA/HMAC tests
- */
- for (hashno = hashnolow; hashno <= hashnohigh; ++hashno) {
- if (printResults == PRINTTEXT)
- printf("Hash %s\n", hashes[hashno].name);
- err = shaSuccess;
-
- for (loopno = 1; (loopno <= loopnohigh) && (err == shaSuccess);
- ++loopno) {
- if (hashstr)
- err = hash(0, loopno, hashno, hashstr, hashlen, 1,
- numberExtrabits, extrabits, (const unsigned char *)hmacKey,
- hmaclen, resultstr, hashes[hashno].hashsize, printResults,
- printPassFail);
-
- else if (randomseedstr)
- randomtest(hashno, randomseedstr, hashes[hashno].hashsize, 0,
- randomcount, printResults, printPassFail);
-
- else if (hashfilename)
- err = hashfile(hashno, hashfilename, extrabits,
-
-
-
-Eastlake 3rd & Hansen Informational [Page 101]
-\f
-RFC 4634 SHAs and HMAC-SHAs July 2006
-
-
- numberExtrabits, 0,
- (const unsigned char *)hmacKey, hmaclen,
- resultstr, hashes[hashno].hashsize,
- printResults, printPassFail);
-
- else if (hashFilename)
- err = hashfile(hashno, hashFilename, extrabits,
- numberExtrabits, 1,
- (const unsigned char *)hmacKey, hmaclen,
- resultstr, hashes[hashno].hashsize,
- printResults, printPassFail);
-
- else /* standard tests */ {
- for (testno = testnolow;
- (testno <= testnohigh) && (err == shaSuccess); ++testno) {
- if (runHmacTests) {
- err = hash(testno, loopno, hashno,
- hmachashes[testno].dataarray[hashno] ?
- hmachashes[testno].dataarray[hashno] :
- hmachashes[testno].dataarray[1] ?
- hmachashes[testno].dataarray[1] :
- hmachashes[testno].dataarray[0],
- hmachashes[testno].datalength[hashno] ?
- hmachashes[testno].datalength[hashno] :
- hmachashes[testno].datalength[1] ?
- hmachashes[testno].datalength[1] :
- hmachashes[testno].datalength[0],
- 1, 0, 0,
- (const unsigned char *)(
- hmachashes[testno].keyarray[hashno] ?
- hmachashes[testno].keyarray[hashno] :
- hmachashes[testno].keyarray[1] ?
- hmachashes[testno].keyarray[1] :
- hmachashes[testno].keyarray[0]),
- hmachashes[testno].keylength[hashno] ?
- hmachashes[testno].keylength[hashno] :
- hmachashes[testno].keylength[1] ?
- hmachashes[testno].keylength[1] :
- hmachashes[testno].keylength[0],
- hmachashes[testno].resultarray[hashno],
- hmachashes[testno].resultlength[hashno],
- printResults, printPassFail);
- } else {
- err = hash(testno, loopno, hashno,
- hashes[hashno].tests[testno].testarray,
- hashes[hashno].tests[testno].length,
- hashes[hashno].tests[testno].repeatcount,
- hashes[hashno].tests[testno].numberExtrabits,
-
-
-
-Eastlake 3rd & Hansen Informational [Page 102]
-\f
-RFC 4634 SHAs and HMAC-SHAs July 2006
-
-
- hashes[hashno].tests[testno].extrabits, 0, 0,
- hashes[hashno].tests[testno].resultarray,
- hashes[hashno].hashsize,
- printResults, printPassFail);
- }
- }
-
- if (!runHmacTests) {
- randomtest(hashno, hashes[hashno].randomtest,
- hashes[hashno].hashsize, hashes[hashno].randomresults,
- RANDOMCOUNT, printResults, printPassFail);
- }
- }
- }
- }
-
- /* Test some error returns */
- if (checkErrors) {
- testErrors(hashnolow, hashnohigh, printResults, printPassFail);
- }
-
- return 0;
-}
-
-/*
- * Compare two strings, case independently.
- * Equivalent to strcasecmp() found on some systems.
- */
-int scasecmp(const char *s1, const char *s2)
-{
- for (;;) {
- char u1 = tolower(*s1++);
- char u2 = tolower(*s2++);
- if (u1 != u2)
- return u1 - u2;
- if (u1 == '\0')
- return 0;
- }
-}
-
-/*
- * This is a copy of getopt provided for those systems that do not
- * have it. The name was changed to xgetopt to not conflict on those
- * systems that do have it. Similarly, optarg, optind and opterr
- * were renamed to xoptarg, xoptind and xopterr.
- *
- * Copyright 1990, 1991, 1992 by the Massachusetts Institute of
- * Technology and UniSoft Group Limited.
-
-
-
-Eastlake 3rd & Hansen Informational [Page 103]
-\f
-RFC 4634 SHAs and HMAC-SHAs July 2006
-
-
- *
- * Permission to use, copy, modify, distribute, and sell this software
- * and its documentation for any purpose is hereby granted without fee,
- * provided that the above copyright notice appear in all copies and
- * that both that copyright notice and this permission notice appear in
- * supporting documentation, and that the names of MIT and UniSoft not
- * be used in advertising or publicity pertaining to distribution of
- * the software without specific, written prior permission. MIT and
- * UniSoft make no representations about the suitability of this
- * software for any purpose. It is provided "as is" without express
- * or implied warranty.
- *
- * $XConsortium: getopt.c,v 1.2 92/07/01 11:59:04 rws Exp $
- * NB: Reformatted to match above style.
- */
-
-char *xoptarg;
-int xoptind = 1;
-int xopterr = 1;
-
-static int xgetopt(int argc, char **argv, const char *optstring)
-{
- static int avplace;
- char *ap;
- char *cp;
- int c;
-
- if (xoptind >= argc)
- return EOF;
-
- ap = argv[xoptind] + avplace;
-
- /* At beginning of arg but not an option */
- if (avplace == 0) {
- if (ap[0] != '-')
- return EOF;
- else if (ap[1] == '-') {
- /* Special end of options option */
- xoptind++;
- return EOF;
- } else if (ap[1] == '\0')
- return EOF; /* single '-' is not allowed */
- }
-
- /* Get next letter */
- avplace++;
- c = *++ap;
-
-
-
-
-Eastlake 3rd & Hansen Informational [Page 104]
-\f
-RFC 4634 SHAs and HMAC-SHAs July 2006
-
-
- cp = strchr(optstring, c);
- if (cp == NULL || c == ':') {
- if (xopterr)
- fprintf(stderr, "Unrecognised option -- %c\n", c);
- return '?';
- }
-
- if (cp[1] == ':') {
- /* There should be an option arg */
- avplace = 0;
- if (ap[1] == '\0') {
- /* It is a separate arg */
- if (++xoptind >= argc) {
- if (xopterr)
- fprintf(stderr, "Option requires an argument\n");
- return '?';
- }
- xoptarg = argv[xoptind++];
- } else {
- /* is attached to option letter */
- xoptarg = ap + 1;
- ++xoptind;
- }
- } else {
- /* If we are out of letters then go to next arg */
- if (ap[1] == '\0') {
- ++xoptind;
- avplace = 0;
- }
-
- xoptarg = NULL;
- }
- return c;
-}
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-Eastlake 3rd & Hansen Informational [Page 105]
-\f
-RFC 4634 SHAs and HMAC-SHAs July 2006
-
-
-9. Security Considerations
-
- This document is intended to provides the Internet community
- convenient access to source code that implements the United States of
- America Federal Information Processing Standard Secure Hash
- Algorithms (SHAs) [FIPS180-2] and HMACs based upon these one-way hash
- functions. See license in Section 1.1. No independent assertion of
- the security of this hash function by the authors for any particular
- use is intended.
-
-10. Normative References
-
- [FIPS180-2] "Secure Hash Standard", United States of America,
- National Institute of Standards and Technology, Federal
- Information Processing Standard (FIPS) 180-2,
- http://csrc.nist.gov/publications/fips/fips180-2/
- fips180-2withchangenotice.pdf.
-
- [RFC2104] Krawczyk, H., Bellare, M., and R. Canetti, "HMAC: Keyed-
- Hashing for Message Authentication", RFC 2104, February
- 1997.
-
-11. Informative References
-
- [RFC2202] Cheng, P. and R. Glenn, "Test Cases for HMAC-MD5 and
- HMAC-SHA-1", RFC 2202, September 1997.
-
- [RFC3174] Eastlake 3rd, D. and P. Jones, "US Secure Hash Algorithm
- 1 (SHA1)", RFC 3174, September 2001.
-
- [RFC3874] Housley, R., "A 224-bit One-way Hash Function: SHA-224",
- RFC 3874, September 2004.
-
- [RFC4086] Eastlake, D., 3rd, Schiller, J., and S. Crocker,
- "Randomness Requirements for Security", BCP 106, RFC
- 4086, June 2005.
-
- [RFC4231] Nystrom, M., "Identifiers and Test Vectors for HMAC-SHA-
- 224, HMAC-SHA-256, HMAC-SHA-384, and HMAC-SHA-512", RFC
- 4231, December 2005.
-
- [SHAVS] "The Secure Hash Algorithm Validation System (SHAVS)",
- http://csrc.nist.gov/cryptval/shs/SHAVS.pdf.
-
-
-
-
-
-
-
-
-Eastlake 3rd & Hansen Informational [Page 106]
-\f
-RFC 4634 SHAs and HMAC-SHAs July 2006
-
-
-Authors' Addresses
-
- Donald E. Eastlake, 3rd
- Motorola Laboratories
- 155 Beaver Street
- Milford, MA 01757 USA
-
- Phone: +1-508-786-7554 (w)
- EMail: donald.eastlake@motorola.com
-
-
- Tony Hansen
- AT&T Laboratories
- 200 Laurel Ave.
- Middletown, NJ 07748 USA
-
- Phone: +1-732-420-8934 (w)
- EMail: tony+shs@maillennium.att.com
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-Eastlake 3rd & Hansen Informational [Page 107]
-\f
-RFC 4634 SHAs and HMAC-SHAs July 2006
-
-
-Full Copyright Statement
-
- Copyright (C) The Internet Society (2006).
-
- This document is subject to the rights, licenses and restrictions
- contained in BCP 78, and except as set forth therein, the authors
- retain all their rights.
-
- This document and the information contained herein are provided on an
- "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS
- OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND THE INTERNET
- ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED,
- INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE
- INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED
- WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
-
-Intellectual Property
-
- The IETF takes no position regarding the validity or scope of any
- Intellectual Property Rights or other rights that might be claimed to
- pertain to the implementation or use of the technology described in
- this document or the extent to which any license under such rights
- might or might not be available; nor does it represent that it has
- made any independent effort to identify any such rights. Information
- on the procedures with respect to rights in RFC documents can be
- found in BCP 78 and BCP 79.
-
- Copies of IPR disclosures made to the IETF Secretariat and any
- assurances of licenses to be made available, or the result of an
- attempt made to obtain a general license or permission for the use of
- such proprietary rights by implementers or users of this
- specification can be obtained from the IETF on-line IPR repository at
- http://www.ietf.org/ipr.
-
- The IETF invites any interested party to bring to its attention any
- copyrights, patents or patent applications, or other proprietary
- rights that may cover technology that may be required to implement
- this standard. Please address the information to the IETF at
- ietf-ipr@ietf.org.
-
-Acknowledgement
-
- Funding for the RFC Editor function is provided by the IETF
- Administrative Support Activity (IASA).
-
-
-
-
-
-
-
-Eastlake 3rd & Hansen Informational [Page 108]
-\f
+++ /dev/null
-
-
-
-
-
-
-Network Working Group O. Kolkman
-Request for Comments: 4641 R. Gieben
-Obsoletes: 2541 NLnet Labs
-Category: Informational September 2006
-
-
- DNSSEC Operational Practices
-
-Status of This Memo
-
- This memo provides information for the Internet community. It does
- not specify an Internet standard of any kind. Distribution of this
- memo is unlimited.
-
-Copyright Notice
-
- Copyright (C) The Internet Society (2006).
-
-Abstract
-
- This document describes a set of practices for operating the DNS with
- security extensions (DNSSEC). The target audience is zone
- administrators deploying DNSSEC.
-
- The document discusses operational aspects of using keys and
- signatures in the DNS. It discusses issues of key generation, key
- storage, signature generation, key rollover, and related policies.
-
- This document obsoletes RFC 2541, as it covers more operational
- ground and gives more up-to-date requirements with respect to key
- sizes and the new DNSSEC specification.
-
-
-
-
-
-
-
-
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-
-Table of Contents
-
- 1. Introduction ....................................................3
- 1.1. The Use of the Term 'key' ..................................4
- 1.2. Time Definitions ...........................................4
- 2. Keeping the Chain of Trust Intact ...............................5
- 3. Keys Generation and Storage .....................................6
- 3.1. Zone and Key Signing Keys ..................................6
- 3.1.1. Motivations for the KSK and ZSK Separation ..........6
- 3.1.2. KSKs for High-Level Zones ...........................7
- 3.2. Key Generation .............................................8
- 3.3. Key Effectivity Period .....................................8
- 3.4. Key Algorithm ..............................................9
- 3.5. Key Sizes ..................................................9
- 3.6. Private Key Storage .......................................11
- 4. Signature Generation, Key Rollover, and Related Policies .......12
- 4.1. Time in DNSSEC ............................................12
- 4.1.1. Time Considerations ................................12
- 4.2. Key Rollovers .............................................14
- 4.2.1. Zone Signing Key Rollovers .........................14
- 4.2.1.1. Pre-Publish Key Rollover ..................15
- 4.2.1.2. Double Signature Zone Signing Key
- Rollover ..................................17
- 4.2.1.3. Pros and Cons of the Schemes ..............18
- 4.2.2. Key Signing Key Rollovers ..........................18
- 4.2.3. Difference Between ZSK and KSK Rollovers ...........20
- 4.2.4. Automated Key Rollovers ............................21
- 4.3. Planning for Emergency Key Rollover .......................21
- 4.3.1. KSK Compromise .....................................22
- 4.3.1.1. Keeping the Chain of Trust Intact .........22
- 4.3.1.2. Breaking the Chain of Trust ...............23
- 4.3.2. ZSK Compromise .....................................23
- 4.3.3. Compromises of Keys Anchored in Resolvers ..........24
- 4.4. Parental Policies .........................................24
- 4.4.1. Initial Key Exchanges and Parental Policies
- Considerations .....................................24
- 4.4.2. Storing Keys or Hashes? ............................25
- 4.4.3. Security Lameness ..................................25
- 4.4.4. DS Signature Validity Period .......................26
- 5. Security Considerations ........................................26
- 6. Acknowledgments ................................................26
- 7. References .....................................................27
- 7.1. Normative References ......................................27
- 7.2. Informative References ....................................28
- Appendix A. Terminology ...........................................30
- Appendix B. Zone Signing Key Rollover How-To ......................31
- Appendix C. Typographic Conventions ...............................32
-
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-1. Introduction
-
- This document describes how to run a DNS Security (DNSSEC)-enabled
- environment. It is intended for operators who have knowledge of the
- DNS (see RFC 1034 [1] and RFC 1035 [2]) and want to deploy DNSSEC.
- See RFC 4033 [4] for an introduction to DNSSEC, RFC 4034 [5] for the
- newly introduced Resource Records (RRs), and RFC 4035 [6] for the
- protocol changes.
-
- During workshops and early operational deployment tests, operators
- and system administrators have gained experience about operating the
- DNS with security extensions (DNSSEC). This document translates
- these experiences into a set of practices for zone administrators.
- At the time of writing, there exists very little experience with
- DNSSEC in production environments; this document should therefore
- explicitly not be seen as representing 'Best Current Practices'.
-
- The procedures herein are focused on the maintenance of signed zones
- (i.e., signing and publishing zones on authoritative servers). It is
- intended that maintenance of zones such as re-signing or key
- rollovers be transparent to any verifying clients on the Internet.
-
- The structure of this document is as follows. In Section 2, we
- discuss the importance of keeping the "chain of trust" intact.
- Aspects of key generation and storage of private keys are discussed
- in Section 3; the focus in this section is mainly on the private part
- of the key(s). Section 4 describes considerations concerning the
- public part of the keys. Since these public keys appear in the DNS
- one has to take into account all kinds of timing issues, which are
- discussed in Section 4.1. Section 4.2 and Section 4.3 deal with the
- rollover, or supercession, of keys. Finally, Section 4.4 discusses
- considerations on how parents deal with their children's public keys
- in order to maintain chains of trust.
-
- The typographic conventions used in this document are explained in
- Appendix C.
-
- Since this is a document with operational suggestions and there are
- no protocol specifications, the RFC 2119 [7] language does not apply.
-
- This document obsoletes RFC 2541 [12] to reflect the evolution of the
- underlying DNSSEC protocol since then. Changes in the choice of
- cryptographic algorithms, DNS record types and type names, and the
- parent-child key and signature exchange demanded a major rewrite and
- additional information and explanation.
-
-
-
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-1.1. The Use of the Term 'key'
-
- It is assumed that the reader is familiar with the concept of
- asymmetric keys on which DNSSEC is based (public key cryptography
- [17]). Therefore, this document will use the term 'key' rather
- loosely. Where it is written that 'a key is used to sign data' it is
- assumed that the reader understands that it is the private part of
- the key pair that is used for signing. It is also assumed that the
- reader understands that the public part of the key pair is published
- in the DNSKEY Resource Record and that it is the public part that is
- used in key exchanges.
-
-1.2. Time Definitions
-
- In this document, we will be using a number of time-related terms.
- The following definitions apply:
-
- o "Signature validity period" The period that a signature is valid.
- It starts at the time specified in the signature inception field
- of the RRSIG RR and ends at the time specified in the expiration
- field of the RRSIG RR.
-
- o "Signature publication period" Time after which a signature (made
- with a specific key) is replaced with a new signature (made with
- the same key). This replacement takes place by publishing the
- relevant RRSIG in the master zone file. After one stops
- publishing an RRSIG in a zone, it may take a while before the
- RRSIG has expired from caches and has actually been removed from
- the DNS.
-
- o "Key effectivity period" The period during which a key pair is
- expected to be effective. This period is defined as the time
- between the first inception time stamp and the last expiration
- date of any signature made with this key, regardless of any
- discontinuity in the use of the key. The key effectivity period
- can span multiple signature validity periods.
-
- o "Maximum/Minimum Zone Time to Live (TTL)" The maximum or minimum
- value of the TTLs from the complete set of RRs in a zone. Note
- that the minimum TTL is not the same as the MINIMUM field in the
- SOA RR. See [11] for more information.
-
-
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-2. Keeping the Chain of Trust Intact
-
- Maintaining a valid chain of trust is important because broken chains
- of trust will result in data being marked as Bogus (as defined in [4]
- Section 5), which may cause entire (sub)domains to become invisible
- to verifying clients. The administrators of secured zones have to
- realize that their zone is, to verifying clients, part of a chain of
- trust.
-
- As mentioned in the introduction, the procedures herein are intended
- to ensure that maintenance of zones, such as re-signing or key
- rollovers, will be transparent to the verifying clients on the
- Internet.
-
- Administrators of secured zones will have to keep in mind that data
- published on an authoritative primary server will not be immediately
- seen by verifying clients; it may take some time for the data to be
- transferred to other secondary authoritative nameservers and clients
- may be fetching data from caching non-authoritative servers. In this
- light, note that the time for a zone transfer from master to slave is
- negligible when using NOTIFY [9] and incremental transfer (IXFR) [8].
- It increases when full zone transfers (AXFR) are used in combination
- with NOTIFY. It increases even more if you rely on full zone
- transfers based on only the SOA timing parameters for refresh.
-
- For the verifying clients, it is important that data from secured
- zones can be used to build chains of trust regardless of whether the
- data came directly from an authoritative server, a caching
- nameserver, or some middle box. Only by carefully using the
- available timing parameters can a zone administrator ensure that the
- data necessary for verification can be obtained.
-
- The responsibility for maintaining the chain of trust is shared by
- administrators of secured zones in the chain of trust. This is most
- obvious in the case of a 'key compromise' when a trade-off between
- maintaining a valid chain of trust and replacing the compromised keys
- as soon as possible must be made. Then zone administrators will have
- to make a trade-off, between keeping the chain of trust intact --
- thereby allowing for attacks with the compromised key -- or
- deliberately breaking the chain of trust and making secured
- subdomains invisible to security-aware resolvers. Also see Section
- 4.3.
-
-
-
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-3. Keys Generation and Storage
-
- This section describes a number of considerations with respect to the
- security of keys. It deals with the generation, effectivity period,
- size, and storage of private keys.
-
-3.1. Zone and Key Signing Keys
-
- The DNSSEC validation protocol does not distinguish between different
- types of DNSKEYs. All DNSKEYs can be used during the validation. In
- practice, operators use Key Signing and Zone Signing Keys and use the
- so-called Secure Entry Point (SEP) [3] flag to distinguish between
- them during operations. The dynamics and considerations are
- discussed below.
-
- To make zone re-signing and key rollover procedures easier to
- implement, it is possible to use one or more keys as Key Signing Keys
- (KSKs). These keys will only sign the apex DNSKEY RRSet in a zone.
- Other keys can be used to sign all the RRSets in a zone and are
- referred to as Zone Signing Keys (ZSKs). In this document, we assume
- that KSKs are the subset of keys that are used for key exchanges with
- the parent and potentially for configuration as trusted anchors --
- the SEP keys. In this document, we assume a one-to-one mapping
- between KSK and SEP keys and we assume the SEP flag to be set on all
- KSKs.
-
-3.1.1. Motivations for the KSK and ZSK Separation
-
- Differentiating between the KSK and ZSK functions has several
- advantages:
-
- o No parent/child interaction is required when ZSKs are updated.
-
- o The KSK can be made stronger (i.e., using more bits in the key
- material). This has little operational impact since it is only
- used to sign a small fraction of the zone data. Also, the KSK is
- only used to verify the zone's key set, not for other RRSets in
- the zone.
-
- o As the KSK is only used to sign a key set, which is most probably
- updated less frequently than other data in the zone, it can be
- stored separately from and in a safer location than the ZSK.
-
- o A KSK can have a longer key effectivity period.
-
- For almost any method of key management and zone signing, the KSK is
- used less frequently than the ZSK. Once a key set is signed with the
- KSK, all the keys in the key set can be used as ZSKs. If a ZSK is
-
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- compromised, it can be simply dropped from the key set. The new key
- set is then re-signed with the KSK.
-
- Given the assumption that for KSKs the SEP flag is set, the KSK can
- be distinguished from a ZSK by examining the flag field in the DNSKEY
- RR. If the flag field is an odd number it is a KSK. If it is an
- even number it is a ZSK.
-
- The Zone Signing Key can be used to sign all the data in a zone on a
- regular basis. When a Zone Signing Key is to be rolled, no
- interaction with the parent is needed. This allows for signature
- validity periods on the order of days.
-
- The Key Signing Key is only to be used to sign the DNSKEY RRs in a
- zone. If a Key Signing Key is to be rolled over, there will be
- interactions with parties other than the zone administrator. These
- can include the registry of the parent zone or administrators of
- verifying resolvers that have the particular key configured as secure
- entry points. Hence, the key effectivity period of these keys can
- and should be made much longer. Although, given a long enough key,
- the key effectivity period can be on the order of years, we suggest
- planning for a key effectivity on the order of a few months so that a
- key rollover remains an operational routine.
-
-3.1.2. KSKs for High-Level Zones
-
- Higher-level zones are generally more sensitive than lower-level
- zones. Anyone controlling or breaking the security of a zone thereby
- obtains authority over all of its subdomains (except in the case of
- resolvers that have locally configured the public key of a subdomain,
- in which case this, and only this, subdomain wouldn't be affected by
- the compromise of the parent zone). Therefore, extra care should be
- taken with high-level zones, and strong keys should be used.
-
- The root zone is the most critical of all zones. Someone controlling
- or compromising the security of the root zone would control the
- entire DNS namespace of all resolvers using that root zone (except in
- the case of resolvers that have locally configured the public key of
- a subdomain). Therefore, the utmost care must be taken in the
- securing of the root zone. The strongest and most carefully handled
- keys should be used. The root zone private key should always be kept
- off-line.
-
- Many resolvers will start at a root server for their access to and
- authentication of DNS data. Securely updating the trust anchors in
- an enormous population of resolvers around the world will be
- extremely difficult.
-
-
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-3.2. Key Generation
-
- Careful generation of all keys is a sometimes overlooked but
- absolutely essential element in any cryptographically secure system.
- The strongest algorithms used with the longest keys are still of no
- use if an adversary can guess enough to lower the size of the likely
- key space so that it can be exhaustively searched. Technical
- suggestions for the generation of random keys will be found in RFC
- 4086 [14]. One should carefully assess if the random number
- generator used during key generation adheres to these suggestions.
-
- Keys with a long effectivity period are particularly sensitive as
- they will represent a more valuable target and be subject to attack
- for a longer time than short-period keys. It is strongly recommended
- that long-term key generation occur off-line in a manner isolated
- from the network via an air gap or, at a minimum, high-level secure
- hardware.
-
-3.3. Key Effectivity Period
-
- For various reasons, keys in DNSSEC need to be changed once in a
- while. The longer a key is in use, the greater the probability that
- it will have been compromised through carelessness, accident,
- espionage, or cryptanalysis. Furthermore, when key rollovers are too
- rare an event, they will not become part of the operational habit and
- there is risk that nobody on-site will remember the procedure for
- rollover when the need is there.
-
- From a purely operational perspective, a reasonable key effectivity
- period for Key Signing Keys is 13 months, with the intent to replace
- them after 12 months. An intended key effectivity period of a month
- is reasonable for Zone Signing Keys.
-
- For key sizes that match these effectivity periods, see Section 3.5.
-
- As argued in Section 3.1.2, securely updating trust anchors will be
- extremely difficult. On the other hand, the "operational habit"
- argument does also apply to trust anchor reconfiguration. If a short
- key effectivity period is used and the trust anchor configuration has
- to be revisited on a regular basis, the odds that the configuration
- tends to be forgotten is smaller. The trade-off is against a system
- that is so dynamic that administrators of the validating clients will
- not be able to follow the modifications.
-
- Key effectivity periods can be made very short, as in a few minutes.
- But when replacing keys one has to take the considerations from
- Section 4.1 and Section 4.2 into account.
-
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-3.4. Key Algorithm
-
- There are currently three different types of algorithms that can be
- used in DNSSEC: RSA, DSA, and elliptic curve cryptography. The
- latter is fairly new and has yet to be standardized for usage in
- DNSSEC.
-
- RSA has been developed in an open and transparent manner. As the
- patent on RSA expired in 2000, its use is now also free.
-
- DSA has been developed by the National Institute of Standards and
- Technology (NIST). The creation of signatures takes roughly the same
- time as with RSA, but is 10 to 40 times as slow for verification
- [17].
-
- We suggest the use of RSA/SHA-1 as the preferred algorithm for the
- key. The current known attacks on RSA can be defeated by making your
- key longer. As the MD5 hashing algorithm is showing cracks, we
- recommend the usage of SHA-1.
-
- At the time of publication, it is known that the SHA-1 hash has
- cryptanalysis issues. There is work in progress on addressing these
- issues. We recommend the use of public key algorithms based on
- hashes stronger than SHA-1 (e.g., SHA-256), as soon as these
- algorithms are available in protocol specifications (see [19] and
- [20]) and implementations.
-
-3.5. Key Sizes
-
- When choosing key sizes, zone administrators will need to take into
- account how long a key will be used, how much data will be signed
- during the key publication period (see Section 8.10 of [17]), and,
- optionally, how large the key size of the parent is. As the chain of
- trust really is "a chain", there is not much sense in making one of
- the keys in the chain several times larger then the others. As
- always, it's the weakest link that defines the strength of the entire
- chain. Also see Section 3.1.1 for a discussion of how keys serving
- different roles (ZSK vs. KSK) may need different key sizes.
-
- Generating a key of the correct size is a difficult problem; RFC 3766
- [13] tries to deal with that problem. The first part of the
- selection procedure in Section 1 of the RFC states:
-
- 1. Determine the attack resistance necessary to satisfy the
- security requirements of the application. Do this by
- estimating the minimum number of computer operations that the
- attacker will be forced to do in order to compromise the
-
-
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- security of the system and then take the logarithm base two of
- that number. Call that logarithm value "n".
-
- A 1996 report recommended 90 bits as a good all-around choice
- for system security. The 90 bit number should be increased by
- about 2/3 bit/year, or about 96 bits in 2005.
-
- [13] goes on to explain how this number "n" can be used to calculate
- the key sizes in public key cryptography. This culminated in the
- table given below (slightly modified for our purpose):
-
- +-------------+-----------+--------------+
- | System | | |
- | requirement | Symmetric | RSA or DSA |
- | for attack | key size | modulus size |
- | resistance | (bits) | (bits) |
- | (bits) | | |
- +-------------+-----------+--------------+
- | 70 | 70 | 947 |
- | 80 | 80 | 1228 |
- | 90 | 90 | 1553 |
- | 100 | 100 | 1926 |
- | 150 | 150 | 4575 |
- | 200 | 200 | 8719 |
- | 250 | 250 | 14596 |
- +-------------+-----------+--------------+
-
- The key sizes given are rather large. This is because these keys are
- resilient against a trillionaire attacker. Assuming this rich
- attacker will not attack your key and that the key is rolled over
- once a year, we come to the following recommendations about KSK
- sizes: 1024 bits for low-value domains, 1300 bits for medium-value
- domains, and 2048 bits for high-value domains.
-
- Whether a domain is of low, medium, or high value depends solely on
- the views of the zone owner. One could, for instance, view leaf
- nodes in the DNS as of low value, and top-level domains (TLDs) or the
- root zone of high value. The suggested key sizes should be safe for
- the next 5 years.
-
- As ZSKs can be rolled over more easily (and thus more often), the key
- sizes can be made smaller. But as said in the introduction of this
- paragraph, making the ZSKs' key sizes too small (in relation to the
- KSKs' sizes) doesn't make much sense. Try to limit the difference in
- size to about 100 bits.
-
-
-
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- Note that nobody can see into the future and that these key sizes are
- only provided here as a guide. Further information can be found in
- [16] and Section 7.5 of [17]. It should be noted though that [16] is
- already considered overly optimistic about what key sizes are
- considered safe.
-
- One final note concerning key sizes. Larger keys will increase the
- sizes of the RRSIG and DNSKEY records and will therefore increase the
- chance of DNS UDP packet overflow. Also, the time it takes to
- validate and create RRSIGs increases with larger keys, so don't
- needlessly double your key sizes.
-
-3.6. Private Key Storage
-
- It is recommended that, where possible, zone private keys and the
- zone file master copy that is to be signed be kept and used in off-
- line, non-network-connected, physically secure machines only.
- Periodically, an application can be run to add authentication to a
- zone by adding RRSIG and NSEC RRs. Then the augmented file can be
- transferred.
-
- When relying on dynamic update to manage a signed zone [10], be aware
- that at least one private key of the zone will have to reside on the
- master server. This key is only as secure as the amount of exposure
- the server receives to unknown clients and the security of the host.
- Although not mandatory, one could administer the DNS in the following
- way. The master that processes the dynamic updates is unavailable
- from generic hosts on the Internet, it is not listed in the NS RR
- set, although its name appears in the SOA RRs MNAME field. The
- nameservers in the NS RRSet are able to receive zone updates through
- NOTIFY, IXFR, AXFR, or an out-of-band distribution mechanism. This
- approach is known as the "hidden master" setup.
-
- The ideal situation is to have a one-way information flow to the
- network to avoid the possibility of tampering from the network.
- Keeping the zone master file on-line on the network and simply
- cycling it through an off-line signer does not do this. The on-line
- version could still be tampered with if the host it resides on is
- compromised. For maximum security, the master copy of the zone file
- should be off-net and should not be updated based on an unsecured
- network mediated communication.
-
- In general, keeping a zone file off-line will not be practical and
- the machines on which zone files are maintained will be connected to
- a network. Operators are advised to take security measures to shield
- unauthorized access to the master copy.
-
-
-
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- For dynamically updated secured zones [10], both the master copy and
- the private key that is used to update signatures on updated RRs will
- need to be on-line.
-
-4. Signature Generation, Key Rollover, and Related Policies
-
-4.1. Time in DNSSEC
-
- Without DNSSEC, all times in the DNS are relative. The SOA fields
- REFRESH, RETRY, and EXPIRATION are timers used to determine the time
- elapsed after a slave server synchronized with a master server. The
- Time to Live (TTL) value and the SOA RR minimum TTL parameter [11]
- are used to determine how long a forwarder should cache data after it
- has been fetched from an authoritative server. By using a signature
- validity period, DNSSEC introduces the notion of an absolute time in
- the DNS. Signatures in DNSSEC have an expiration date after which
- the signature is marked as invalid and the signed data is to be
- considered Bogus.
-
-4.1.1. Time Considerations
-
- Because of the expiration of signatures, one should consider the
- following:
-
- o We suggest the Maximum Zone TTL of your zone data to be a fraction
- of your signature validity period.
-
- If the TTL would be of similar order as the signature validity
- period, then all RRSets fetched during the validity period
- would be cached until the signature expiration time. Section
- 7.1 of [4] suggests that "the resolver may use the time
- remaining before expiration of the signature validity period of
- a signed RRSet as an upper bound for the TTL". As a result,
- query load on authoritative servers would peak at signature
- expiration time, as this is also the time at which records
- simultaneously expire from caches.
-
- To avoid query load peaks, we suggest the TTL on all the RRs in
- your zone to be at least a few times smaller than your
- signature validity period.
-
- o We suggest the signature publication period to end at least one
- Maximum Zone TTL duration before the end of the signature validity
- period.
-
-
-
-
-
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- Re-signing a zone shortly before the end of the signature
- validity period may cause simultaneous expiration of data from
- caches. This in turn may lead to peaks in the load on
- authoritative servers.
-
- o We suggest the Minimum Zone TTL to be long enough to both fetch
- and verify all the RRs in the trust chain. In workshop
- environments, it has been demonstrated [18] that a low TTL (under
- 5 to 10 minutes) caused disruptions because of the following two
- problems:
-
- 1. During validation, some data may expire before the
- validation is complete. The validator should be able to
- keep all data until it is completed. This applies to all
- RRs needed to complete the chain of trust: DSes, DNSKEYs,
- RRSIGs, and the final answers, i.e., the RRSet that is
- returned for the initial query.
-
- 2. Frequent verification causes load on recursive nameservers.
- Data at delegation points, DSes, DNSKEYs, and RRSIGs
- benefit from caching. The TTL on those should be
- relatively long.
-
- o Slave servers will need to be able to fetch newly signed zones
- well before the RRSIGs in the zone served by the slave server pass
- their signature expiration time.
-
- When a slave server is out of sync with its master and data in
- a zone is signed by expired signatures, it may be better for
- the slave server not to give out any answer.
-
- Normally, a slave server that is not able to contact a master
- server for an extended period will expire a zone. When that
- happens, the server will respond differently to queries for
- that zone. Some servers issue SERVFAIL, whereas others turn
- off the 'AA' bit in the answers. The time of expiration is set
- in the SOA record and is relative to the last successful
- refresh between the master and the slave servers. There exists
- no coupling between the signature expiration of RRSIGs in the
- zone and the expire parameter in the SOA.
-
- If the server serves a DNSSEC zone, then it may well happen
- that the signatures expire well before the SOA expiration timer
- counts down to zero. It is not possible to completely prevent
- this from happening by tweaking the SOA parameters. However,
- the effects can be minimized where the SOA expiration time is
- equal to or shorter than the signature validity period. The
- consequence of an authoritative server not being able to update
-
-
-
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-
-
- a zone, whilst that zone includes expired signatures, is that
- non-secure resolvers will continue to be able to resolve data
- served by the particular slave servers while security-aware
- resolvers will experience problems because of answers being
- marked as Bogus.
-
- We suggest the SOA expiration timer being approximately one
- third or one fourth of the signature validity period. It will
- allow problems with transfers from the master server to be
- noticed before the actual signature times out. We also suggest
- that operators of nameservers that supply secondary services
- develop 'watch dogs' to spot upcoming signature expirations in
- zones they slave, and take appropriate action.
-
- When determining the value for the expiration parameter one has
- to take the following into account: What are the chances that
- all my secondaries expire the zone? How quickly can I reach an
- administrator of secondary servers to load a valid zone? These
- questions are not DNSSEC specific but may influence the choice
- of your signature validity intervals.
-
-4.2. Key Rollovers
-
- A DNSSEC key cannot be used forever (see Section 3.3). So key
- rollovers -- or supercessions, as they are sometimes called -- are a
- fact of life when using DNSSEC. Zone administrators who are in the
- process of rolling their keys have to take into account that data
- published in previous versions of their zone still lives in caches.
- When deploying DNSSEC, this becomes an important consideration;
- ignoring data that may be in caches may lead to loss of service for
- clients.
-
- The most pressing example of this occurs when zone material signed
- with an old key is being validated by a resolver that does not have
- the old zone key cached. If the old key is no longer present in the
- current zone, this validation fails, marking the data "Bogus".
- Alternatively, an attempt could be made to validate data that is
- signed with a new key against an old key that lives in a local cache,
- also resulting in data being marked "Bogus".
-
-4.2.1. Zone Signing Key Rollovers
-
- For "Zone Signing Key rollovers", there are two ways to make sure
- that during the rollover data still cached can be verified with the
- new key sets or newly generated signatures can be verified with the
- keys still in caches. One schema, described in Section 4.2.1.2, uses
-
-
-
-
-
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-
-
- double signatures; the other uses key pre-publication (Section
- 4.2.1.1). The pros, cons, and recommendations are described in
- Section 4.2.1.3.
-
-4.2.1.1. Pre-Publish Key Rollover
-
- This section shows how to perform a ZSK rollover without the need to
- sign all the data in a zone twice -- the "pre-publish key rollover".
- This method has advantages in the case of a key compromise. If the
- old key is compromised, the new key has already been distributed in
- the DNS. The zone administrator is then able to quickly switch to
- the new key and remove the compromised key from the zone. Another
- major advantage is that the zone size does not double, as is the case
- with the double signature ZSK rollover. A small "how-to" for this
- kind of rollover can be found in Appendix B.
-
- Pre-publish key rollover involves four stages as follows:
-
- ----------------------------------------------------------------
- initial new DNSKEY new RRSIGs DNSKEY removal
- ----------------------------------------------------------------
- SOA0 SOA1 SOA2 SOA3
- RRSIG10(SOA0) RRSIG10(SOA1) RRSIG11(SOA2) RRSIG11(SOA3)
-
- DNSKEY1 DNSKEY1 DNSKEY1 DNSKEY1
- DNSKEY10 DNSKEY10 DNSKEY10 DNSKEY11
- DNSKEY11 DNSKEY11
- RRSIG1 (DNSKEY) RRSIG1 (DNSKEY) RRSIG1(DNSKEY) RRSIG1 (DNSKEY)
- RRSIG10(DNSKEY) RRSIG10(DNSKEY) RRSIG11(DNSKEY) RRSIG11(DNSKEY)
- ----------------------------------------------------------------
-
- Pre-Publish Key Rollover
-
- initial: Initial version of the zone: DNSKEY 1 is the Key Signing
- Key. DNSKEY 10 is used to sign all the data of the zone, the Zone
- Signing Key.
-
- new DNSKEY: DNSKEY 11 is introduced into the key set. Note that no
- signatures are generated with this key yet, but this does not
- secure against brute force attacks on the public key. The minimum
- duration of this pre-roll phase is the time it takes for the data
- to propagate to the authoritative servers plus TTL value of the
- key set.
-
- new RRSIGs: At the "new RRSIGs" stage (SOA serial 2), DNSKEY 11 is
- used to sign the data in the zone exclusively (i.e., all the
- signatures from DNSKEY 10 are removed from the zone). DNSKEY 10
- remains published in the key set. This way data that was loaded
-
-
-
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-
-
- into caches from version 1 of the zone can still be verified with
- key sets fetched from version 2 of the zone. The minimum time
- that the key set including DNSKEY 10 is to be published is the
- time that it takes for zone data from the previous version of the
- zone to expire from old caches, i.e., the time it takes for this
- zone to propagate to all authoritative servers plus the Maximum
- Zone TTL value of any of the data in the previous version of the
- zone.
-
- DNSKEY removal: DNSKEY 10 is removed from the zone. The key set, now
- only containing DNSKEY 1 and DNSKEY 11, is re-signed with the
- DNSKEY 1.
-
- The above scheme can be simplified by always publishing the "future"
- key immediately after the rollover. The scheme would look as follows
- (we show two rollovers); the future key is introduced in "new DNSKEY"
- as DNSKEY 12 and again a newer one, numbered 13, in "new DNSKEY
- (II)":
-
- ----------------------------------------------------------------
- initial new RRSIGs new DNSKEY
- ----------------------------------------------------------------
- SOA0 SOA1 SOA2
- RRSIG10(SOA0) RRSIG11(SOA1) RRSIG11(SOA2)
-
- DNSKEY1 DNSKEY1 DNSKEY1
- DNSKEY10 DNSKEY10 DNSKEY11
- DNSKEY11 DNSKEY11 DNSKEY12
- RRSIG1(DNSKEY) RRSIG1 (DNSKEY) RRSIG1(DNSKEY)
- RRSIG10(DNSKEY) RRSIG11(DNSKEY) RRSIG11(DNSKEY)
- ----------------------------------------------------------------
-
- ----------------------------------------------------------------
- new RRSIGs (II) new DNSKEY (II)
- ----------------------------------------------------------------
- SOA3 SOA4
- RRSIG12(SOA3) RRSIG12(SOA4)
-
- DNSKEY1 DNSKEY1
- DNSKEY11 DNSKEY12
- DNSKEY12 DNSKEY13
- RRSIG1(DNSKEY) RRSIG1(DNSKEY)
- RRSIG12(DNSKEY) RRSIG12(DNSKEY)
- ----------------------------------------------------------------
-
- Pre-Publish Key Rollover, Showing Two Rollovers
-
-
-
-
-
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-
-
- Note that the key introduced in the "new DNSKEY" phase is not used
- for production yet; the private key can thus be stored in a
- physically secure manner and does not need to be 'fetched' every time
- a zone needs to be signed.
-
-4.2.1.2. Double Signature Zone Signing Key Rollover
-
- This section shows how to perform a ZSK key rollover using the double
- zone data signature scheme, aptly named "double signature rollover".
-
- During the "new DNSKEY" stage the new version of the zone file will
- need to propagate to all authoritative servers and the data that
- exists in (distant) caches will need to expire, requiring at least
- the Maximum Zone TTL.
-
- Double signature ZSK rollover involves three stages as follows:
-
- ----------------------------------------------------------------
- initial new DNSKEY DNSKEY removal
- ----------------------------------------------------------------
- SOA0 SOA1 SOA2
- RRSIG10(SOA0) RRSIG10(SOA1) RRSIG11(SOA2)
- RRSIG11(SOA1)
-
- DNSKEY1 DNSKEY1 DNSKEY1
- DNSKEY10 DNSKEY10 DNSKEY11
- DNSKEY11
- RRSIG1(DNSKEY) RRSIG1(DNSKEY) RRSIG1(DNSKEY)
- RRSIG10(DNSKEY) RRSIG10(DNSKEY) RRSIG11(DNSKEY)
- RRSIG11(DNSKEY)
- ----------------------------------------------------------------
-
- Double Signature Zone Signing Key Rollover
-
- initial: Initial Version of the zone: DNSKEY 1 is the Key Signing
- Key. DNSKEY 10 is used to sign all the data of the zone, the Zone
- Signing Key.
-
- new DNSKEY: At the "New DNSKEY" stage (SOA serial 1) DNSKEY 11 is
- introduced into the key set and all the data in the zone is signed
- with DNSKEY 10 and DNSKEY 11. The rollover period will need to
- continue until all data from version 0 of the zone has expired
- from remote caches. This will take at least the Maximum Zone TTL
- of version 0 of the zone.
-
- DNSKEY removal: DNSKEY 10 is removed from the zone. All the
- signatures from DNSKEY 10 are removed from the zone. The key set,
- now only containing DNSKEY 11, is re-signed with DNSKEY 1.
-
-
-
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-
-
- At every instance, RRSIGs from the previous version of the zone can
- be verified with the DNSKEY RRSet from the current version and the
- other way around. The data from the current version can be verified
- with the data from the previous version of the zone. The duration of
- the "new DNSKEY" phase and the period between rollovers should be at
- least the Maximum Zone TTL.
-
- Making sure that the "new DNSKEY" phase lasts until the signature
- expiration time of the data in initial version of the zone is
- recommended. This way all caches are cleared of the old signatures.
- However, this duration could be considerably longer than the Maximum
- Zone TTL, making the rollover a lengthy procedure.
-
- Note that in this example we assumed that the zone was not modified
- during the rollover. New data can be introduced in the zone as long
- as it is signed with both keys.
-
-4.2.1.3. Pros and Cons of the Schemes
-
- Pre-publish key rollover: This rollover does not involve signing the
- zone data twice. Instead, before the actual rollover, the new key
- is published in the key set and thus is available for
- cryptanalysis attacks. A small disadvantage is that this process
- requires four steps. Also the pre-publish scheme involves more
- parental work when used for KSK rollovers as explained in Section
- 4.2.3.
-
- Double signature ZSK rollover: The drawback of this signing scheme is
- that during the rollover the number of signatures in your zone
- doubles; this may be prohibitive if you have very big zones. An
- advantage is that it only requires three steps.
-
-4.2.2. Key Signing Key Rollovers
-
- For the rollover of a Key Signing Key, the same considerations as for
- the rollover of a Zone Signing Key apply. However, we can use a
- double signature scheme to guarantee that old data (only the apex key
- set) in caches can be verified with a new key set and vice versa.
- Since only the key set is signed with a KSK, zone size considerations
- do not apply.
-
-
-
-
-
-
-
-
-
-
-
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-
-
- --------------------------------------------------------------------
- initial new DNSKEY DS change DNSKEY removal
- --------------------------------------------------------------------
- Parent:
- SOA0 --------> SOA1 -------->
- RRSIGpar(SOA0) --------> RRSIGpar(SOA1) -------->
- DS1 --------> DS2 -------->
- RRSIGpar(DS) --------> RRSIGpar(DS) -------->
-
-
- Child:
- SOA0 SOA1 --------> SOA2
- RRSIG10(SOA0) RRSIG10(SOA1) --------> RRSIG10(SOA2)
- -------->
- DNSKEY1 DNSKEY1 --------> DNSKEY2
- DNSKEY2 -------->
- DNSKEY10 DNSKEY10 --------> DNSKEY10
- RRSIG1 (DNSKEY) RRSIG1 (DNSKEY) --------> RRSIG2 (DNSKEY)
- RRSIG2 (DNSKEY) -------->
- RRSIG10(DNSKEY) RRSIG10(DNSKEY) --------> RRSIG10(DNSKEY)
- --------------------------------------------------------------------
-
- Stages of Deployment for a Double Signature Key Signing Key Rollover
-
- initial: Initial version of the zone. The parental DS points to
- DNSKEY1. Before the rollover starts, the child will have to
- verify what the TTL is of the DS RR that points to DNSKEY1 -- it
- is needed during the rollover and we refer to the value as TTL_DS.
-
- new DNSKEY: During the "new DNSKEY" phase, the zone administrator
- generates a second KSK, DNSKEY2. The key is provided to the
- parent, and the child will have to wait until a new DS RR has been
- generated that points to DNSKEY2. After that DS RR has been
- published on all servers authoritative for the parent's zone, the
- zone administrator has to wait at least TTL_DS to make sure that
- the old DS RR has expired from caches.
-
- DS change: The parent replaces DS1 with DS2.
-
- DNSKEY removal: DNSKEY1 has been removed.
-
- The scenario above puts the responsibility for maintaining a valid
- chain of trust with the child. It also is based on the premise that
- the parent only has one DS RR (per algorithm) per zone. An
- alternative mechanism has been considered. Using an established
- trust relation, the interaction can be performed in-band, and the
- removal of the keys by the child can possibly be signaled by the
- parent. In this mechanism, there are periods where there are two DS
-
-
-
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-
-
- RRs at the parent. Since at the moment of writing the protocol for
- this interaction has not been developed, further discussion is out of
- scope for this document.
-
-4.2.3. Difference Between ZSK and KSK Rollovers
-
- Note that KSK rollovers and ZSK rollovers are different in the sense
- that a KSK rollover requires interaction with the parent (and
- possibly replacing of trust anchors) and the ensuing delay while
- waiting for it.
-
- A zone key rollover can be handled in two different ways: pre-publish
- (Section 4.2.1.1) and double signature (Section 4.2.1.2).
-
- As the KSK is used to validate the key set and because the KSK is not
- changed during a ZSK rollover, a cache is able to validate the new
- key set of the zone. The pre-publish method would also work for a
- KSK rollover. The records that are to be pre-published are the
- parental DS RRs. The pre-publish method has some drawbacks for KSKs.
- We first describe the rollover scheme and then indicate these
- drawbacks.
-
- --------------------------------------------------------------------
- initial new DS new DNSKEY DS/DNSKEY removal
- --------------------------------------------------------------------
- Parent:
- SOA0 SOA1 --------> SOA2
- RRSIGpar(SOA0) RRSIGpar(SOA1) --------> RRSIGpar(SOA2)
- DS1 DS1 --------> DS2
- DS2 -------->
- RRSIGpar(DS) RRSIGpar(DS) --------> RRSIGpar(DS)
-
-
- Child:
- SOA0 --------> SOA1 SOA1
- RRSIG10(SOA0) --------> RRSIG10(SOA1) RRSIG10(SOA1)
- -------->
- DNSKEY1 --------> DNSKEY2 DNSKEY2
- -------->
- DNSKEY10 --------> DNSKEY10 DNSKEY10
- RRSIG1 (DNSKEY) --------> RRSIG2(DNSKEY) RRSIG2 (DNSKEY)
- RRSIG10(DNSKEY) --------> RRSIG10(DNSKEY) RRSIG10(DNSKEY)
- --------------------------------------------------------------------
-
- Stages of Deployment for a Pre-Publish Key Signing Key Rollover
-
-
-
-
-
-
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-
-
- When the child zone wants to roll, it notifies the parent during the
- "new DS" phase and submits the new key (or the corresponding DS) to
- the parent. The parent publishes DS1 and DS2, pointing to DNSKEY1
- and DNSKEY2, respectively. During the rollover ("new DNSKEY" phase),
- which can take place as soon as the new DS set propagated through the
- DNS, the child replaces DNSKEY1 with DNSKEY2. Immediately after that
- ("DS/DNSKEY removal" phase), it can notify the parent that the old DS
- record can be deleted.
-
- The drawbacks of this scheme are that during the "new DS" phase the
- parent cannot verify the match between the DS2 RR and DNSKEY2 using
- the DNS -- as DNSKEY2 is not yet published. Besides, we introduce a
- "security lame" key (see Section 4.4.3). Finally, the child-parent
- interaction consists of two steps. The "double signature" method
- only needs one interaction.
-
-4.2.4. Automated Key Rollovers
-
- As keys must be renewed periodically, there is some motivation to
- automate the rollover process. Consider the following:
-
- o ZSK rollovers are easy to automate as only the child zone is
- involved.
-
- o A KSK rollover needs interaction between parent and child. Data
- exchange is needed to provide the new keys to the parent;
- consequently, this data must be authenticated and integrity must
- be guaranteed in order to avoid attacks on the rollover.
-
-4.3. Planning for Emergency Key Rollover
-
- This section deals with preparation for a possible key compromise.
- Our advice is to have a documented procedure ready for when a key
- compromise is suspected or confirmed.
-
- When the private material of one of your keys is compromised it can
- be used for as long as a valid trust chain exists. A trust chain
- remains intact for
-
- o as long as a signature over the compromised key in the trust chain
- is valid,
-
- o as long as a parental DS RR (and signature) points to the
- compromised key,
-
- o as long as the key is anchored in a resolver and is used as a
- starting point for validation (this is generally the hardest to
- update).
-
-
-
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-
-
- While a trust chain to your compromised key exists, your namespace is
- vulnerable to abuse by anyone who has obtained illegitimate
- possession of the key. Zone operators have to make a trade-off if
- the abuse of the compromised key is worse than having data in caches
- that cannot be validated. If the zone operator chooses to break the
- trust chain to the compromised key, data in caches signed with this
- key cannot be validated. However, if the zone administrator chooses
- to take the path of a regular rollover, the malicious key holder can
- spoof data so that it appears to be valid.
-
-4.3.1. KSK Compromise
-
- A zone containing a DNSKEY RRSet with a compromised KSK is vulnerable
- as long as the compromised KSK is configured as trust anchor or a
- parental DS points to it.
-
- A compromised KSK can be used to sign the key set of an attacker's
- zone. That zone could be used to poison the DNS.
-
- Therefore, when the KSK has been compromised, the trust anchor or the
- parental DS should be replaced as soon as possible. It is local
- policy whether to break the trust chain during the emergency
- rollover. The trust chain would be broken when the compromised KSK
- is removed from the child's zone while the parent still has a DS
- pointing to the compromised KSK (the assumption is that there is only
- one DS at the parent. If there are multiple DSes this does not apply
- -- however the chain of trust of this particular key is broken).
-
- Note that an attacker's zone still uses the compromised KSK and the
- presence of a parental DS would cause the data in this zone to appear
- as valid. Removing the compromised key would cause the attacker's
- zone to appear as valid and the child's zone as Bogus. Therefore, we
- advise not to remove the KSK before the parent has a DS to a new KSK
- in place.
-
-4.3.1.1. Keeping the Chain of Trust Intact
-
- If we follow this advice, the timing of the replacement of the KSK is
- somewhat critical. The goal is to remove the compromised KSK as soon
- as the new DS RR is available at the parent. And also make sure that
- the signature made with a new KSK over the key set with the
- compromised KSK in it expires just after the new DS appears at the
- parent, thus removing the old cruft in one swoop.
-
- The procedure is as follows:
-
- 1. Introduce a new KSK into the key set, keep the compromised KSK in
- the key set.
-
-
-
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-
-
- 2. Sign the key set, with a short validity period. The validity
- period should expire shortly after the DS is expected to appear
- in the parent and the old DSes have expired from caches.
-
- 3. Upload the DS for this new key to the parent.
-
- 4. Follow the procedure of the regular KSK rollover: Wait for the DS
- to appear in the authoritative servers and then wait as long as
- the TTL of the old DS RRs. If necessary re-sign the DNSKEY RRSet
- and modify/extend the expiration time.
-
- 5. Remove the compromised DNSKEY RR from the zone and re-sign the
- key set using your "normal" validity interval.
-
- An additional danger of a key compromise is that the compromised key
- could be used to facilitate a legitimate DNSKEY/DS rollover and/or
- nameserver changes at the parent. When that happens, the domain may
- be in dispute. An authenticated out-of-band and secure notify
- mechanism to contact a parent is needed in this case.
-
- Note that this is only a problem when the DNSKEY and or DS records
- are used for authentication at the parent.
-
-4.3.1.2. Breaking the Chain of Trust
-
- There are two methods to break the chain of trust. The first method
- causes the child zone to appear 'Bogus' to validating resolvers. The
- other causes the child zone to appear 'insecure'. These are
- described below.
-
- In the method that causes the child zone to appear 'Bogus' to
- validating resolvers, the child zone replaces the current KSK with a
- new one and re-signs the key set. Next it sends the DS of the new
- key to the parent. Only after the parent has placed the new DS in
- the zone is the child's chain of trust repaired.
-
- An alternative method of breaking the chain of trust is by removing
- the DS RRs from the parent zone altogether. As a result, the child
- zone would become insecure.
-
-4.3.2. ZSK Compromise
-
- Primarily because there is no parental interaction required when a
- ZSK is compromised, the situation is less severe than with a KSK
- compromise. The zone must still be re-signed with a new ZSK as soon
- as possible. As this is a local operation and requires no
- communication between the parent and child, this can be achieved
- fairly quickly. However, one has to take into account that just as
-
-
-
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-
-
- with a normal rollover the immediate disappearance of the old
- compromised key may lead to verification problems. Also note that as
- long as the RRSIG over the compromised ZSK is not expired the zone
- may be still at risk.
-
-4.3.3. Compromises of Keys Anchored in Resolvers
-
- A key can also be pre-configured in resolvers. For instance, if
- DNSSEC is successfully deployed the root key may be pre-configured in
- most security aware resolvers.
-
- If trust-anchor keys are compromised, the resolvers using these keys
- should be notified of this fact. Zone administrators may consider
- setting up a mailing list to communicate the fact that a SEP key is
- about to be rolled over. This communication will of course need to
- be authenticated, e.g., by using digital signatures.
-
- End-users faced with the task of updating an anchored key should
- always validate the new key. New keys should be authenticated out-
- of-band, for example, through the use of an announcement website that
- is secured using secure sockets (TLS) [21].
-
-4.4. Parental Policies
-
-4.4.1. Initial Key Exchanges and Parental Policies Considerations
-
- The initial key exchange is always subject to the policies set by the
- parent. When designing a key exchange policy one should take into
- account that the authentication and authorization mechanisms used
- during a key exchange should be as strong as the authentication and
- authorization mechanisms used for the exchange of delegation
- information between parent and child. That is, there is no implicit
- need in DNSSEC to make the authentication process stronger than it
- was in DNS.
-
- Using the DNS itself as the source for the actual DNSKEY material,
- with an out-of-band check on the validity of the DNSKEY, has the
- benefit that it reduces the chances of user error. A DNSKEY query
- tool can make use of the SEP bit [3] to select the proper key from a
- DNSSEC key set, thereby reducing the chance that the wrong DNSKEY is
- sent. It can validate the self-signature over a key; thereby
- verifying the ownership of the private key material. Fetching the
- DNSKEY from the DNS ensures that the chain of trust remains intact
- once the parent publishes the DS RR indicating the child is secure.
-
- Note: the out-of-band verification is still needed when the key
- material is fetched via the DNS. The parent can never be sure
- whether or not the DNSKEY RRs have been spoofed.
-
-
-
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-
-
-4.4.2. Storing Keys or Hashes?
-
- When designing a registry system one should consider which of the
- DNSKEYs and/or the corresponding DSes to store. Since a child zone
- might wish to have a DS published using a message digest algorithm
- not yet understood by the registry, the registry can't count on being
- able to generate the DS record from a raw DNSKEY. Thus, we recommend
- that registry systems at least support storing DS records.
-
- It may also be useful to store DNSKEYs, since having them may help
- during troubleshooting and, as long as the child's chosen message
- digest is supported, the overhead of generating DS records from them
- is minimal. Having an out-of-band mechanism, such as a registry
- directory (e.g., Whois), to find out which keys are used to generate
- DS Resource Records for specific owners and/or zones may also help
- with troubleshooting.
-
- The storage considerations also relate to the design of the customer
- interface and the method by which data is transferred between
- registrant and registry; Will the child zone administrator be able to
- upload DS RRs with unknown hash algorithms or does the interface only
- allow DNSKEYs? In the registry-registrar model, one can use the
- DNSSEC extensions to the Extensible Provisioning Protocol (EPP) [15],
- which allows transfer of DS RRs and optionally DNSKEY RRs.
-
-4.4.3. Security Lameness
-
- Security lameness is defined as what happens when a parent has a DS
- RR pointing to a non-existing DNSKEY RR. When this happens, the
- child's zone may be marked "Bogus" by verifying DNS clients.
-
- As part of a comprehensive delegation check, the parent could, at key
- exchange time, verify that the child's key is actually configured in
- the DNS. However, if a parent does not understand the hashing
- algorithm used by child, the parental checks are limited to only
- comparing the key id.
-
- Child zones should be very careful in removing DNSKEY material,
- specifically SEP keys, for which a DS RR exists.
-
- Once a zone is "security lame", a fix (e.g., removing a DS RR) will
- take time to propagate through the DNS.
-
-
-
-
-
-
-
-
-
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-4.4.4. DS Signature Validity Period
-
- Since the DS can be replayed as long as it has a valid signature, a
- short signature validity period over the DS minimizes the time a
- child is vulnerable in the case of a compromise of the child's
- KSK(s). A signature validity period that is too short introduces the
- possibility that a zone is marked "Bogus" in case of a configuration
- error in the signer. There may not be enough time to fix the
- problems before signatures expire. Something as mundane as operator
- unavailability during weekends shows the need for DS signature
- validity periods longer than 2 days. We recommend an absolute
- minimum for a DS signature validity period of a few days.
-
- The maximum signature validity period of the DS record depends on how
- long child zones are willing to be vulnerable after a key compromise.
- On the other hand, shortening the DS signature validity interval
- increases the operational risk for the parent. Therefore, the parent
- may have policy to use a signature validity interval that is
- considerably longer than the child would hope for.
-
- A compromise between the operational constraints of the parent and
- minimizing damage for the child may result in a DS signature validity
- period somewhere between a week and months.
-
- In addition to the signature validity period, which sets a lower
- bound on the number of times the zone owner will need to sign the
- zone data and which sets an upper bound to the time a child is
- vulnerable after key compromise, there is the TTL value on the DS
- RRs. Shortening the TTL means that the authoritative servers will
- see more queries. But on the other hand, a short TTL lowers the
- persistence of DS RRSets in caches thereby increasing the speed with
- which updated DS RRSets propagate through the DNS.
-
-5. Security Considerations
-
- DNSSEC adds data integrity to the DNS. This document tries to assess
- the operational considerations to maintain a stable and secure DNSSEC
- service. Not taking into account the 'data propagation' properties
- in the DNS will cause validation failures and may make secured zones
- unavailable to security-aware resolvers.
-
-6. Acknowledgments
-
- Most of the ideas in this document were the result of collective
- efforts during workshops, discussions, and tryouts.
-
- At the risk of forgetting individuals who were the original
- contributors of the ideas, we would like to acknowledge people who
-
-
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- were actively involved in the compilation of this document. In
- random order: Rip Loomis, Olafur Gudmundsson, Wesley Griffin, Michael
- Richardson, Scott Rose, Rick van Rein, Tim McGinnis, Gilles Guette
- Olivier Courtay, Sam Weiler, Jelte Jansen, Niall O'Reilly, Holger
- Zuleger, Ed Lewis, Hilarie Orman, Marcos Sanz, and Peter Koch.
-
- Some material in this document has been copied from RFC 2541 [12].
-
- Mike StJohns designed the key exchange between parent and child
- mentioned in the last paragraph of Section 4.2.2
-
- Section 4.2.4 was supplied by G. Guette and O. Courtay.
-
- Emma Bretherick, Adrian Bedford, and Lindy Foster corrected many of
- the spelling and style issues.
-
- Kolkman and Gieben take the blame for introducing all miscakes (sic).
-
- While working on this document, Kolkman was employed by the RIPE NCC
- and Gieben was employed by NLnet Labs.
-
-7. References
-
-7.1. Normative References
-
- [1] Mockapetris, P., "Domain names - concepts and facilities", STD
- 13, RFC 1034, November 1987.
-
- [2] Mockapetris, P., "Domain names - implementation and
- specification", STD 13, RFC 1035, November 1987.
-
- [3] Kolkman, O., Schlyter, J., and E. Lewis, "Domain Name System
- KEY (DNSKEY) Resource Record (RR) Secure Entry Point (SEP)
- Flag", RFC 3757, May 2004.
-
- [4] Arends, R., Austein, R., Larson, M., Massey, D., and S. Rose,
- "DNS Security Introduction and Requirements", RFC 4033, March
- 2005.
-
- [5] Arends, R., Austein, R., Larson, M., Massey, D., and S. Rose,
- "Resource Records for the DNS Security Extensions", RFC 4034,
- March 2005.
-
- [6] Arends, R., Austein, R., Larson, M., Massey, D., and S. Rose,
- "Protocol Modifications for the DNS Security Extensions", RFC
- 4035, March 2005.
-
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-7.2. Informative References
-
- [7] Bradner, S., "Key words for use in RFCs to Indicate Requirement
- Levels", BCP 14, RFC 2119, March 1997.
-
- [8] Ohta, M., "Incremental Zone Transfer in DNS", RFC 1995, August
- 1996.
-
- [9] Vixie, P., "A Mechanism for Prompt Notification of Zone Changes
- (DNS NOTIFY)", RFC 1996, August 1996.
-
- [10] Wellington, B., "Secure Domain Name System (DNS) Dynamic
- Update", RFC 3007, November 2000.
-
- [11] Andrews, M., "Negative Caching of DNS Queries (DNS NCACHE)",
- RFC 2308, March 1998.
-
- [12] Eastlake, D., "DNS Security Operational Considerations", RFC
- 2541, March 1999.
-
- [13] Orman, H. and P. Hoffman, "Determining Strengths For Public
- Keys Used For Exchanging Symmetric Keys", BCP 86, RFC 3766,
- April 2004.
-
- [14] Eastlake, D., Schiller, J., and S. Crocker, "Randomness
- Requirements for Security", BCP 106, RFC 4086, June 2005.
-
- [15] Hollenbeck, S., "Domain Name System (DNS) Security Extensions
- Mapping for the Extensible Provisioning Protocol (EPP)", RFC
- 4310, December 2005.
-
- [16] Lenstra, A. and E. Verheul, "Selecting Cryptographic Key
- Sizes", The Journal of Cryptology 14 (255-293), 2001.
-
- [17] Schneier, B., "Applied Cryptography: Protocols, Algorithms, and
- Source Code in C", ISBN (hardcover) 0-471-12845-7, ISBN
- (paperback) 0-471-59756-2, Published by John Wiley & Sons Inc.,
- 1996.
-
- [18] Rose, S., "NIST DNSSEC workshop notes", June 2001.
-
- [19] Jansen, J., "Use of RSA/SHA-256 DNSKEY and RRSIG Resource
- Records in DNSSEC", Work in Progress, January 2006.
-
- [20] Hardaker, W., "Use of SHA-256 in DNSSEC Delegation Signer (DS)
- Resource Records (RRs)", RFC 4509, May 2006.
-
-
-
-
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- [21] Blake-Wilson, S., Nystrom, M., Hopwood, D., Mikkelsen, J., and
- T. Wright, "Transport Layer Security (TLS) Extensions", RFC
- 4366, April 2006.
-
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-Appendix A. Terminology
-
- In this document, there is some jargon used that is defined in other
- documents. In most cases, we have not copied the text from the
- documents defining the terms but have given a more elaborate
- explanation of the meaning. Note that these explanations should not
- be seen as authoritative.
-
- Anchored key: A DNSKEY configured in resolvers around the globe.
- This key is hard to update, hence the term anchored.
-
- Bogus: Also see Section 5 of [4]. An RRSet in DNSSEC is marked
- "Bogus" when a signature of an RRSet does not validate against a
- DNSKEY.
-
- Key Signing Key or KSK: A Key Signing Key (KSK) is a key that is used
- exclusively for signing the apex key set. The fact that a key is
- a KSK is only relevant to the signing tool.
-
- Key size: The term 'key size' can be substituted by 'modulus size'
- throughout the document. It is mathematically more correct to use
- modulus size, but as this is a document directed at operators we
- feel more at ease with the term key size.
-
- Private and public keys: DNSSEC secures the DNS through the use of
- public key cryptography. Public key cryptography is based on the
- existence of two (mathematically related) keys, a public key and a
- private key. The public keys are published in the DNS by use of
- the DNSKEY Resource Record (DNSKEY RR). Private keys should
- remain private.
-
- Key rollover: A key rollover (also called key supercession in some
- environments) is the act of replacing one key pair with another at
- the end of a key effectivity period.
-
- Secure Entry Point (SEP) key: A KSK that has a parental DS record
- pointing to it or is configured as a trust anchor. Although not
- required by the protocol, we recommend that the SEP flag [3] is
- set on these keys.
-
- Self-signature: This only applies to signatures over DNSKEYs; a
- signature made with DNSKEY x, over DNSKEY x is called a self-
- signature. Note: without further information, self-signatures
- convey no trust. They are useful to check the authenticity of the
- DNSKEY, i.e., they can be used as a hash.
-
-
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- Singing the zone file: The term used for the event where an
- administrator joyfully signs its zone file while producing melodic
- sound patterns.
-
- Signer: The system that has access to the private key material and
- signs the Resource Record sets in a zone. A signer may be
- configured to sign only parts of the zone, e.g., only those RRSets
- for which existing signatures are about to expire.
-
- Zone Signing Key (ZSK): A key that is used for signing all data in a
- zone. The fact that a key is a ZSK is only relevant to the
- signing tool.
-
- Zone administrator: The 'role' that is responsible for signing a zone
- and publishing it on the primary authoritative server.
-
-Appendix B. Zone Signing Key Rollover How-To
-
- Using the pre-published signature scheme and the most conservative
- method to assure oneself that data does not live in caches, here
- follows the "how-to".
-
- Step 0: The preparation: Create two keys and publish both in your key
- set. Mark one of the keys "active" and the other "published".
- Use the "active" key for signing your zone data. Store the
- private part of the "published" key, preferably off-line. The
- protocol does not provide for attributes to mark a key as active
- or published. This is something you have to do on your own,
- through the use of a notebook or key management tool.
-
- Step 1: Determine expiration: At the beginning of the rollover make a
- note of the highest expiration time of signatures in your zone
- file created with the current key marked as active. Wait until
- the expiration time marked in Step 1 has passed.
-
- Step 2: Then start using the key that was marked "published" to sign
- your data (i.e., mark it "active"). Stop using the key that was
- marked "active"; mark it "rolled".
-
- Step 3: It is safe to engage in a new rollover (Step 1) after at
- least one signature validity period.
-
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-Appendix C. Typographic Conventions
-
- The following typographic conventions are used in this document:
-
- Key notation: A key is denoted by DNSKEYx, where x is a number or an
- identifier, x could be thought of as the key id.
-
- RRSet notations: RRs are only denoted by the type. All other
- information -- owner, class, rdata, and TTL--is left out. Thus:
- "example.com 3600 IN A 192.0.2.1" is reduced to "A". RRSets are a
- list of RRs. A example of this would be "A1, A2", specifying the
- RRSet containing two "A" records. This could again be abbreviated to
- just "A".
-
- Signature notation: Signatures are denoted as RRSIGx(RRSet), which
- means that RRSet is signed with DNSKEYx.
-
- Zone representation: Using the above notation we have simplified the
- representation of a signed zone by leaving out all unnecessary
- details such as the names and by representing all data by "SOAx"
-
- SOA representation: SOAs are represented as SOAx, where x is the
- serial number.
-
- Using this notation the following signed zone:
-
- example.net. 86400 IN SOA ns.example.net. bert.example.net. (
- 2006022100 ; serial
- 86400 ; refresh ( 24 hours)
- 7200 ; retry ( 2 hours)
- 3600000 ; expire (1000 hours)
- 28800 ) ; minimum ( 8 hours)
- 86400 RRSIG SOA 5 2 86400 20130522213204 (
- 20130422213204 14 example.net.
- cmL62SI6iAX46xGNQAdQ... )
- 86400 NS a.iana-servers.net.
- 86400 NS b.iana-servers.net.
- 86400 RRSIG NS 5 2 86400 20130507213204 (
- 20130407213204 14 example.net.
- SO5epiJei19AjXoUpFnQ ... )
- 86400 DNSKEY 256 3 5 (
- EtRB9MP5/AvOuVO0I8XDxy0... ) ; id = 14
- 86400 DNSKEY 257 3 5 (
- gsPW/Yy19GzYIY+Gnr8HABU... ) ; id = 15
- 86400 RRSIG DNSKEY 5 2 86400 20130522213204 (
- 20130422213204 14 example.net.
- J4zCe8QX4tXVGjV4e1r9... )
-
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- 86400 RRSIG DNSKEY 5 2 86400 20130522213204 (
- 20130422213204 15 example.net.
- keVDCOpsSeDReyV6O... )
- 86400 RRSIG NSEC 5 2 86400 20130507213204 (
- 20130407213204 14 example.net.
- obj3HEp1GjnmhRjX... )
- a.example.net. 86400 IN TXT "A label"
- 86400 RRSIG TXT 5 3 86400 20130507213204 (
- 20130407213204 14 example.net.
- IkDMlRdYLmXH7QJnuF3v... )
- 86400 NSEC b.example.com. TXT RRSIG NSEC
- 86400 RRSIG NSEC 5 3 86400 20130507213204 (
- 20130407213204 14 example.net.
- bZMjoZ3bHjnEz0nIsPMM... )
- ...
-
- is reduced to the following representation:
-
- SOA2006022100
- RRSIG14(SOA2006022100)
- DNSKEY14
- DNSKEY15
-
- RRSIG14(KEY)
- RRSIG15(KEY)
-
- The rest of the zone data has the same signature as the SOA record,
- i.e., an RRSIG created with DNSKEY 14.
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-Authors' Addresses
-
- Olaf M. Kolkman
- NLnet Labs
- Kruislaan 419
- Amsterdam 1098 VA
- The Netherlands
-
- EMail: olaf@nlnetlabs.nl
- URI: http://www.nlnetlabs.nl
-
-
- R. (Miek) Gieben
-
- EMail: miek@miek.nl
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-Full Copyright Statement
-
- Copyright (C) The Internet Society (2006).
-
- This document is subject to the rights, licenses and restrictions
- contained in BCP 78, and except as set forth therein, the authors
- retain all their rights.
-
- This document and the information contained herein are provided on an
- "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS
- OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND THE INTERNET
- ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED,
- INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE
- INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED
- WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
-
-Intellectual Property
-
- The IETF takes no position regarding the validity or scope of any
- Intellectual Property Rights or other rights that might be claimed to
- pertain to the implementation or use of the technology described in
- this document or the extent to which any license under such rights
- might or might not be available; nor does it represent that it has
- made any independent effort to identify any such rights. Information
- on the procedures with respect to rights in RFC documents can be
- found in BCP 78 and BCP 79.
-
- Copies of IPR disclosures made to the IETF Secretariat and any
- assurances of licenses to be made available, or the result of an
- attempt made to obtain a general license or permission for the use of
- such proprietary rights by implementers or users of this
- specification can be obtained from the IETF on-line IPR repository at
- http://www.ietf.org/ipr.
-
- The IETF invites any interested party to bring to its attention any
- copyrights, patents or patent applications, or other proprietary
- rights that may cover technology that may be required to implement
- this standard. Please address the information to the IETF at
- ietf-ipr@ietf.org.
-
-Acknowledgement
-
- Funding for the RFC Editor function is provided by the IETF
- Administrative Support Activity (IASA).
-
-
-
-
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