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-
-
-
-
-
-
-Network Working Group R. Hinden
-Request for Comments: 4193 Nokia
-Category: Standards Track B. Haberman
- JHU-APL
- October 2005
-
-
- Unique Local IPv6 Unicast Addresses
-
-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 (2005).
-
-Abstract
-
- This document defines an IPv6 unicast address format that is globally
- unique and is intended for local communications, usually inside of a
- site. These addresses are not expected to be routable on the global
- Internet.
-
-Table of Contents
-
- 1. Introduction ....................................................2
- 2. Acknowledgements ................................................3
- 3. Local IPv6 Unicast Addresses ....................................3
- 3.1. Format .....................................................3
- 3.1.1. Background ..........................................4
- 3.2. Global ID ..................................................4
- 3.2.1. Locally Assigned Global IDs .........................5
- 3.2.2. Sample Code for Pseudo-Random Global ID Algorithm ...5
- 3.2.3. Analysis of the Uniqueness of Global IDs ............6
- 3.3. Scope Definition ...........................................6
- 4. Operational Guidelines ..........................................7
- 4.1. Routing ....................................................7
- 4.2. Renumbering and Site Merging ...............................7
- 4.3. Site Border Router and Firewall Packet Filtering ...........8
- 4.4. DNS Issues .................................................8
- 4.5. Application and Higher Level Protocol Issues ...............9
- 4.6. Use of Local IPv6 Addresses for Local Communication ........9
- 4.7. Use of Local IPv6 Addresses with VPNs .....................10
-
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- 5. Global Routing Considerations ..................................11
- 5.1. From the Standpoint of the Internet .......................11
- 5.2. From the Standpoint of a Site .............................11
- 6. Advantages and Disadvantages ...................................12
- 6.1. Advantages ................................................12
- 6.2. Disadvantages .............................................13
- 7. Security Considerations ........................................13
- 8. IANA Considerations ............................................13
- 9. References .....................................................13
- 9.1. Normative References ......................................13
- 9.2. Informative References ....................................14
-
-1. Introduction
-
- This document defines an IPv6 unicast address format that is globally
- unique and is intended for local communications [IPV6]. These
- addresses are called Unique Local IPv6 Unicast Addresses and are
- abbreviated in this document as Local IPv6 addresses. They are not
- expected to be routable on the global Internet. They are routable
- inside of a more limited area such as a site. They may also be
- routed between a limited set of sites.
-
- Local IPv6 unicast addresses have the following characteristics:
-
- - Globally unique prefix (with high probability of uniqueness).
-
- - Well-known prefix to allow for easy filtering at site
- boundaries.
-
- - Allow sites to be combined or privately interconnected without
- creating any address conflicts or requiring renumbering of
- interfaces that use these prefixes.
-
- - Internet Service Provider independent and can be used for
- communications inside of a site without having any permanent or
- intermittent Internet connectivity.
-
- - If accidentally leaked outside of a site via routing or DNS,
- there is no conflict with any other addresses.
-
- - In practice, applications may treat these addresses like global
- scoped addresses.
-
- This document defines the format of Local IPv6 addresses, how to
- allocate them, and usage considerations including routing, site
- border routers, DNS, application support, VPN usage, and guidelines
- for how to use for local communication inside a site.
-
-
-
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-
- 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].
-
-2. Acknowledgements
-
- The underlying idea of creating Local IPv6 addresses described in
- this document has been proposed a number of times by a variety of
- people. The authors of this document do not claim exclusive credit.
- Credit goes to Brian Carpenter, Christian Huitema, Aidan Williams,
- Andrew White, Charlie Perkins, and many others. The authors would
- also like to thank Brian Carpenter, Charlie Perkins, Harald
- Alvestrand, Keith Moore, Margaret Wasserman, Shannon Behrens, Alan
- Beard, Hans Kruse, Geoff Huston, Pekka Savola, Christian Huitema, Tim
- Chown, Steve Bellovin, Alex Zinin, Tony Hain, Bill Fenner, Sam
- Hartman, and Elwyn Davies for their comments and suggestions on this
- document.
-
-3. Local IPv6 Unicast Addresses
-
-3.1. Format
-
- The Local IPv6 addresses are created using a pseudo-randomly
- allocated global ID. They have the following format:
-
- | 7 bits |1| 40 bits | 16 bits | 64 bits |
- +--------+-+------------+-----------+----------------------------+
- | Prefix |L| Global ID | Subnet ID | Interface ID |
- +--------+-+------------+-----------+----------------------------+
-
- Where:
-
- Prefix FC00::/7 prefix to identify Local IPv6 unicast
- addresses.
-
- L Set to 1 if the prefix is locally assigned.
- Set to 0 may be defined in the future. See
- Section 3.2 for additional information.
-
- Global ID 40-bit global identifier used to create a
- globally unique prefix. See Section 3.2 for
- additional information.
-
- Subnet ID 16-bit Subnet ID is an identifier of a subnet
- within the site.
-
- Interface ID 64-bit Interface ID as defined in [ADDARCH].
-
-
-
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-
-3.1.1. Background
-
- There were a range of choices available when choosing the size of the
- prefix and Global ID field length. There is a direct tradeoff
- between having a Global ID field large enough to support foreseeable
- future growth and not using too much of the IPv6 address space
- needlessly. A reasonable way of evaluating a specific field length
- is to compare it to a projected 2050 world population of 9.3 billion
- [POPUL] and the number of resulting /48 prefixes per person. A range
- of prefix choices is shown in the following table:
-
- Prefix Global ID Number of Prefixes % of IPv6
- Length /48 Prefixes per Person Address Space
-
- /11 37 137,438,953,472 15 0.049%
- /10 38 274,877,906,944 30 0.098%
- /9 39 549,755,813,888 59 0.195%
- /8 40 1,099,511,627,776 118 0.391%
- /7 41 2,199,023,255,552 236 0.781%
- /6 42 4,398,046,511,104 473 1.563%
-
- A very high utilization ratio of these allocations can be assumed
- because the Global ID field does not require internal structure, and
- there is no reason to be able to aggregate the prefixes.
-
- The authors believe that a /7 prefix resulting in a 41-bit Global ID
- space (including the L bit) is a good choice. It provides for a
- large number of assignments (i.e., 2.2 trillion) and at the same time
- uses less than .8% of the total IPv6 address space. It is unlikely
- that this space will be exhausted. If more than this were to be
- needed, then additional IPv6 address space could be allocated for
- this purpose.
-
-3.2. Global ID
-
- The allocation of Global IDs is pseudo-random [RANDOM]. They MUST
- NOT be assigned sequentially or with well-known numbers. This is to
- ensure that there is not any relationship between allocations and to
- help clarify that these prefixes are not intended to be routed
- globally. Specifically, these prefixes are not designed to
- aggregate.
-
- This document defines a specific local method to allocate Global IDs,
- indicated by setting the L bit to 1. Another method, indicated by
- clearing the L bit, may be defined later. Apart from the allocation
- method, all Local IPv6 addresses behave and are treated identically.
-
-
-
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-
- The local assignments are self-generated and do not need any central
- coordination or assignment, but have an extremely high probability of
- being unique.
-
-3.2.1. Locally Assigned Global IDs
-
- Locally assigned Global IDs MUST be generated with a pseudo-random
- algorithm consistent with [RANDOM]. Section 3.2.2 describes a
- suggested algorithm. It is important that all sites generating
- Global IDs use a functionally similar algorithm to ensure there is a
- high probability of uniqueness.
-
- The use of a pseudo-random algorithm to generate Global IDs in the
- locally assigned prefix gives an assurance that any network numbered
- using such a prefix is highly unlikely to have that address space
- clash with any other network that has another locally assigned prefix
- allocated to it. This is a particularly useful property when
- considering a number of scenarios including networks that merge,
- overlapping VPN address space, or hosts mobile between such networks.
-
-3.2.2. Sample Code for Pseudo-Random Global ID Algorithm
-
- The algorithm described below is intended to be used for locally
- assigned Global IDs. In each case the resulting global ID will be
- used in the appropriate prefix as defined in Section 3.2.
-
- 1) Obtain the current time of day in 64-bit NTP format [NTP].
-
- 2) Obtain an EUI-64 identifier from the system running this
- algorithm. If an EUI-64 does not exist, one can be created from
- a 48-bit MAC address as specified in [ADDARCH]. If an EUI-64
- cannot be obtained or created, a suitably unique identifier,
- local to the node, should be used (e.g., system serial number).
-
- 3) Concatenate the time of day with the system-specific identifier
- in order to create a key.
-
- 4) Compute an SHA-1 digest on the key as specified in [FIPS, SHA1];
- the resulting value is 160 bits.
-
- 5) Use the least significant 40 bits as the Global ID.
-
- 6) Concatenate FC00::/7, the L bit set to 1, and the 40-bit Global
- ID to create a Local IPv6 address prefix.
-
- This algorithm will result in a Global ID that is reasonably unique
- and can be used to create a locally assigned Local IPv6 address
- prefix.
-
-
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-
-3.2.3. Analysis of the Uniqueness of Global IDs
-
- The selection of a pseudo random Global ID is similar to the
- selection of an SSRC identifier in RTP/RTCP defined in Section 8.1 of
- [RTP]. This analysis is adapted from that document.
-
- Since Global IDs are chosen randomly (and independently), it is
- possible that separate networks have chosen the same Global ID. For
- any given network, with one or more random Global IDs, that has
- inter-connections to other such networks, having a total of N such
- IDs, the probability that two or more of these IDs will collide can
- be approximated using the formula:
-
- P = 1 - exp(-N**2 / 2**(L+1))
-
- where P is the probability of collision, N is the number of
- interconnected Global IDs, and L is the length of the Global ID.
-
- The following table shows the probability of a collision for a range
- of connections using a 40-bit Global ID field.
-
- Connections Probability of Collision
-
- 2 1.81*10^-12
- 10 4.54*10^-11
- 100 4.54*10^-09
- 1000 4.54*10^-07
- 10000 4.54*10^-05
-
- Based on this analysis, the uniqueness of locally generated Global
- IDs is adequate for sites planning a small to moderate amount of
- inter-site communication using locally generated Global IDs.
-
-3.3. Scope Definition
-
- By default, the scope of these addresses is global. That is, they
- are not limited by ambiguity like the site-local addresses defined in
- [ADDARCH]. Rather, these prefixes are globally unique, and as such,
- their applicability is greater than site-local addresses. Their
- limitation is in the routability of the prefixes, which is limited to
- a site and any explicit routing agreements with other sites to
- propagate them (also see Section 4.1). Also, unlike site-locals, a
- site may have more than one of these prefixes and use them at the
- same time.
-
-
-
-
-
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-
-4. Operational Guidelines
-
- The guidelines in this section do not require any change to the
- normal routing and forwarding functionality in an IPv6 host or
- router. These are configuration and operational usage guidelines.
-
-4.1. Routing
-
- Local IPv6 addresses are designed to be routed inside of a site in
- the same manner as other types of unicast addresses. They can be
- carried in any IPv6 routing protocol without any change.
-
- It is expected that they would share the same Subnet IDs with
- provider-based global unicast addresses, if they were being used
- concurrently [GLOBAL].
-
- The default behavior of exterior routing protocol sessions between
- administrative routing regions must be to ignore receipt of and not
- advertise prefixes in the FC00::/7 block. A network operator may
- specifically configure prefixes longer than FC00::/7 for inter-site
- communication.
-
- If BGP is being used at the site border with an ISP, the default BGP
- configuration must filter out any Local IPv6 address prefixes, both
- incoming and outgoing. It must be set both to keep any Local IPv6
- address prefixes from being advertised outside of the site as well as
- to keep these prefixes from being learned from another site. The
- exception to this is if there are specific /48 or longer routes
- created for one or more Local IPv6 prefixes.
-
- For link-state IGPs, it is suggested that a site utilizing IPv6 local
- address prefixes be contained within one IGP domain or area. By
- containing an IPv6 local address prefix to a single link-state area
- or domain, the distribution of prefixes can be controlled.
-
-4.2. Renumbering and Site Merging
-
- The use of Local IPv6 addresses in a site results in making
- communication that uses these addresses independent of renumbering a
- site's provider-based global addresses.
-
- When merging multiple sites, the addresses created with these
- prefixes are unlikely to need to be renumbered because all of the
- addresses have a high probability of being unique. Routes for each
- specific prefix would have to be configured to allow routing to work
- correctly between the formerly separate sites.
-
-
-
-
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-4.3. Site Border Router and Firewall Packet Filtering
-
- While no serious harm will be done if packets with these addresses
- are sent outside of a site via a default route, it is recommended
- that routers be configured by default to keep any packets with Local
- IPv6 addresses from leaking outside of the site and to keep any site
- prefixes from being advertised outside of their site.
-
- Site border routers and firewalls should be configured to not forward
- any packets with Local IPv6 source or destination addresses outside
- of the site, unless they have been explicitly configured with routing
- information about specific /48 or longer Local IPv6 prefixes. This
- will ensure that packets with Local IPv6 destination addresses will
- not be forwarded outside of the site via a default route. The
- default behavior of these devices should be to install a "reject"
- route for these prefixes. Site border routers should respond with
- the appropriate ICMPv6 Destination Unreachable message to inform the
- source that the packet was not forwarded. [ICMPV6]. This feedback is
- important to avoid transport protocol timeouts.
-
- Routers that maintain peering arrangements between Autonomous Systems
- throughout the Internet should obey the recommendations for site
- border routers, unless configured otherwise.
-
-4.4. DNS Issues
-
- At the present time, AAAA and PTR records for locally assigned local
- IPv6 addresses are not recommended to be installed in the global DNS.
-
- For background on this recommendation, one of the concerns about
- adding AAAA and PTR records to the global DNS for locally assigned
- Local IPv6 addresses stems from the lack of complete assurance that
- the prefixes are unique. There is a small possibility that the same
- locally assigned IPv6 Local addresses will be used by two different
- organizations both claiming to be authoritative with different
- contents. In this scenario, it is likely there will be a connection
- attempt to the closest host with the corresponding locally assigned
- IPv6 Local address. This may result in connection timeouts,
- connection failures indicated by ICMP Destination Unreachable
- messages, or successful connections to the wrong host. Due to this
- concern, adding AAAA records for these addresses to the global DNS is
- thought to be unwise.
-
- Reverse (address-to-name) queries for locally assigned IPv6 Local
- addresses MUST NOT be sent to name servers for the global DNS, due to
- the load that such queries would create for the authoritative name
- servers for the ip6.arpa zone. This form of query load is not
- specific to locally assigned Local IPv6 addresses; any current form
-
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- of local addressing creates additional load of this kind, due to
- reverse queries leaking out of the site. However, since allowing
- such queries to escape from the site serves no useful purpose, there
- is no good reason to make the existing load problems worse.
-
- The recommended way to avoid sending such queries to nameservers for
- the global DNS is for recursive name server implementations to act as
- if they were authoritative for an empty d.f.ip6.arpa zone and return
- RCODE 3 for any such query. Implementations that choose this
- strategy should allow it to be overridden, but returning an RCODE 3
- response for such queries should be the default, both because this
- will reduce the query load problem and also because, if the site
- administrator has not set up the reverse tree corresponding to the
- locally assigned IPv6 Local addresses in use, returning RCODE 3 is in
- fact the correct answer.
-
-4.5. Application and Higher Level Protocol Issues
-
- Application and other higher level protocols can treat Local IPv6
- addresses in the same manner as other types of global unicast
- addresses. No special handling is required. This type of address
- may not be reachable, but that is no different from other types of
- IPv6 global unicast address. Applications need to be able to handle
- multiple addresses that may or may not be reachable at any point in
- time. In most cases, this complexity should be hidden in APIs.
-
- From a host's perspective, the difference between Local IPv6 and
- other types of global unicast addresses shows up as different
- reachability and could be handled by default in that way. In some
- cases, it is better for nodes and applications to treat them
- differently from global unicast addresses. A starting point might be
- to give them preference over global unicast, but fall back to global
- unicast if a particular destination is found to be unreachable. Much
- of this behavior can be controlled by how they are allocated to nodes
- and put into the DNS. However, it is useful if a host can have both
- types of addresses and use them appropriately.
-
- Note that the address selection mechanisms of [ADDSEL], and in
- particular the policy override mechanism replacing default address
- selection, are expected to be used on a site where Local IPv6
- addresses are configured.
-
-4.6. Use of Local IPv6 Addresses for Local Communication
-
- Local IPv6 addresses, like global scope unicast addresses, are only
- assigned to nodes if their use has been enabled (via IPv6 address
- autoconfiguration [ADDAUTO], DHCPv6 [DHCP6], or manually). They are
-
-
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- not created automatically in the way that IPv6 link-local addresses
- are and will not appear or be used unless they are purposely
- configured.
-
- In order for hosts to autoconfigure Local IPv6 addresses, routers
- have to be configured to advertise Local IPv6 /64 prefixes in router
- advertisements, or a DHCPv6 server must have been configured to
- assign them. In order for a node to learn the Local IPv6 address of
- another node, the Local IPv6 address must have been installed in a
- naming system (e.g., DNS, proprietary naming system, etc.) For these
- reasons, controlling their usage in a site is straightforward.
-
- To limit the use of Local IPv6 addresses the following guidelines
- apply:
-
- - Nodes that are to only be reachable inside of a site: The local
- DNS should be configured to only include the Local IPv6
- addresses of these nodes. Nodes with only Local IPv6 addresses
- must not be installed in the global DNS.
-
- - Nodes that are to be limited to only communicate with other
- nodes in the site: These nodes should be set to only
- autoconfigure Local IPv6 addresses via [ADDAUTO] or to only
- receive Local IPv6 addresses via [DHCP6]. Note: For the case
- where both global and Local IPv6 prefixes are being advertised
- on a subnet, this will require a switch in the devices to only
- autoconfigure Local IPv6 addresses.
-
- - Nodes that are to be reachable from inside of the site and from
- outside of the site: The DNS should be configured to include
- the global addresses of these nodes. The local DNS may be
- configured to also include the Local IPv6 addresses of these
- nodes.
-
- - Nodes that can communicate with other nodes inside of the site
- and outside of the site: These nodes should autoconfigure global
- addresses via [ADDAUTO] or receive global address via [DHCP6].
- They may also obtain Local IPv6 addresses via the same
- mechanisms.
-
-4.7. Use of Local IPv6 Addresses with VPNs
-
- Local IPv6 addresses can be used for inter-site Virtual Private
- Networks (VPN) if appropriate routes are set up. Because the
- addresses are unique, these VPNs will work reliably and without the
- need for translation. They have the additional property that they
- will continue to work if the individual sites are renumbered or
- merged.
-
-
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-
-5. Global Routing Considerations
-
- Section 4.1 provides operational guidelines that forbid default
- routing of local addresses between sites. Concerns were raised to
- the IPv6 working group and to the IETF as a whole that sites may
- attempt to use local addresses as globally routed provider-
- independent addresses. This section describes why using local
- addresses as globally-routed provider-independent addresses is
- unadvisable.
-
-5.1. From the Standpoint of the Internet
-
- There is a mismatch between the structure of IPv6 local addresses and
- the normal IPv6 wide area routing model. The /48 prefix of an IPv6
- local addresses fits nowhere in the normal hierarchy of IPv6 unicast
- addresses. Normal IPv6 unicast addresses can be routed
- hierarchically down to physical subnet (link) level and only have to
- be flat-routed on the physical subnet. IPv6 local addresses would
- have to be flat-routed even over the wide area Internet.
-
- Thus, packets whose destination address is an IPv6 local address
- could be routed over the wide area only if the corresponding /48
- prefix were carried by the wide area routing protocol in use, such as
- BGP. This contravenes the operational assumption that long prefixes
- will be aggregated into many fewer short prefixes, to limit the table
- size and convergence time of the routing protocol. If a network uses
- both normal IPv6 addresses [ADDARCH] and IPv6 local addresses, these
- types of addresses will certainly not aggregate with each other,
- since they differ from the most significant bit onwards. Neither
- will IPv6 local addresses aggregate with each other, due to their
- random bit patterns. This means that there would be a very
- significant operational penalty for attempting to use IPv6 local
- address prefixes generically with currently known wide area routing
- technology.
-
-5.2. From the Standpoint of a Site
-
- There are a number of design factors in IPv6 local addresses that
- reduce the likelihood that IPv6 local addresses will be used as
- arbitrary global unicast addresses. These include:
-
- - The default rules to filter packets and routes make it very
- difficult to use IPv6 local addresses for arbitrary use across
- the Internet. For a site to use them as general purpose unicast
- addresses, it would have to make sure that the default rules
- were not being used by all other sites and intermediate ISPs
- used for their current and future communication.
-
-
-
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-
- - They are not mathematically guaranteed to be unique and are not
- registered in public databases. Collisions, while highly
- unlikely, are possible and a collision can compromise the
- integrity of the communications. The lack of public
- registration creates operational problems.
-
- - The addresses are allocated randomly. If a site had multiple
- prefixes that it wanted to be used globally, the cost of
- advertising them would be very high because they could not be
- aggregated.
-
- - They have a long prefix (i.e., /48) so a single local address
- prefix doesn't provide enough address space to be used
- exclusively by the largest organizations.
-
-6. Advantages and Disadvantages
-
-6.1. Advantages
-
- This approach has the following advantages:
-
- - Provides Local IPv6 prefixes that can be used independently of
- any provider-based IPv6 unicast address allocations. This is
- useful for sites not always connected to the Internet or sites
- that wish to have a distinct prefix that can be used to localize
- traffic inside of the site.
-
- - Applications can treat these addresses in an identical manner as
- any other type of global IPv6 unicast addresses.
-
- - Sites can be merged without any renumbering of the Local IPv6
- addresses.
-
- - Sites can change their provider-based IPv6 unicast address
- without disrupting any communication that uses Local IPv6
- addresses.
-
- - Well-known prefix that allows for easy filtering at site
- boundary.
-
- - Can be used for inter-site VPNs.
-
- - If accidently leaked outside of a site via routing or DNS, there
- is no conflict with any other addresses.
-
-
-
-
-
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-
-6.2. Disadvantages
-
- This approach has the following disadvantages:
-
- - Not possible to route Local IPv6 prefixes on the global Internet
- with current routing technology. Consequentially, it is
- necessary to have the default behavior of site border routers to
- filter these addresses.
-
- - There is a very low probability of non-unique locally assigned
- Global IDs being generated by the algorithm in Section 3.2.3.
- This risk can be ignored for all practical purposes, but it
- leads to a theoretical risk of clashing address prefixes.
-
-7. Security Considerations
-
- Local IPv6 addresses do not provide any inherent security to the
- nodes that use them. They may be used with filters at site
- boundaries to keep Local IPv6 traffic inside of the site, but this is
- no more or less secure than filtering any other type of global IPv6
- unicast addresses.
-
- Local IPv6 addresses do allow for address-based security mechanisms,
- including IPsec, across end to end VPN connections.
-
-8. IANA Considerations
-
- The IANA has assigned the FC00::/7 prefix to "Unique Local Unicast".
-
-9. References
-
-9.1. Normative References
-
- [ADDARCH] Hinden, R. and S. Deering, "Internet Protocol Version 6
- (IPv6) Addressing Architecture", RFC 3513, April 2003.
-
- [FIPS] "Federal Information Processing Standards Publication",
- (FIPS PUB) 180-1, Secure Hash Standard, 17 April 1995.
-
- [GLOBAL] Hinden, R., Deering, S., and E. Nordmark, "IPv6 Global
- Unicast Address Format", RFC 3587, August 2003.
-
- [ICMPV6] Conta, A. and S. Deering, "Internet Control Message
- Protocol (ICMPv6) for the Internet Protocol Version 6
- (IPv6) Specification", RFC 2463, December 1998.
-
-
-
-
-
-
-Hinden & Haberman Standards Track [Page 13]
-\f
-RFC 4193 Unique Local IPv6 Unicast Addresses October 2005
-
-
- [IPV6] Deering, S. and R. Hinden, "Internet Protocol, Version 6
- (IPv6) Specification", RFC 2460, December 1998.
-
- [NTP] Mills, D., "Network Time Protocol (Version 3)
- Specification, Implementation and Analysis", RFC 1305,
- March 1992.
-
- [RANDOM] Eastlake, D., 3rd, Schiller, J., and S. Crocker,
- "Randomness Requirements for Security", BCP 106, RFC 4086,
- June 2005.
-
- [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
- Requirement Levels", BCP 14, RFC 2119, March 1997.
-
- [SHA1] Eastlake 3rd, D. and P. Jones, "US Secure Hash Algorithm 1
- (SHA1)", RFC 3174, September 2001.
-
-9.2. Informative References
-
- [ADDAUTO] Thomson, S. and T. Narten, "IPv6 Stateless Address
- Autoconfiguration", RFC 2462, December 1998.
-
- [ADDSEL] Draves, R., "Default Address Selection for Internet
- Protocol version 6 (IPv6)", RFC 3484, February 2003.
-
- [DHCP6] Droms, R., Bound, J., Volz, B., Lemon, T., Perkins, C., and
- M. Carney, "Dynamic Host Configuration Protocol for IPv6
- (DHCPv6)", RFC 3315, July 2003.
-
- [POPUL] Population Reference Bureau, "World Population Data Sheet
- of the Population Reference Bureau 2002", August 2002.
-
- [RTP] Schulzrinne, H., Casner, S., Frederick, R., and V.
- Jacobson, "RTP: A Transport Protocol for Real-Time
- Applications", STD 64, RFC 3550, July 2003.
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-Hinden & Haberman Standards Track [Page 14]
-\f
-RFC 4193 Unique Local IPv6 Unicast Addresses October 2005
-
-
-Authors' Addresses
-
- Robert M. Hinden
- Nokia
- 313 Fairchild Drive
- Mountain View, CA 94043
- USA
-
- Phone: +1 650 625-2004
- EMail: bob.hinden@nokia.com
-
-
- Brian Haberman
- Johns Hopkins University
- Applied Physics Lab
- 11100 Johns Hopkins Road
- Laurel, MD 20723
- USA
-
- Phone: +1 443 778 1319
- EMail: brian@innovationslab.net
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-Hinden & Haberman Standards Track [Page 15]
-\f
-RFC 4193 Unique Local IPv6 Unicast Addresses October 2005
-
-
-Full Copyright Statement
-
- Copyright (C) The Internet Society (2005).
-
- 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 currently provided by the
- Internet Society.
-
-
-
-
-
-
-
-Hinden & Haberman Standards Track [Page 16]
-\f
+++ /dev/null
-
-
-
-
-
-
-Network Working Group J. Schlyter
-Request for Comments: 4255 OpenSSH
-Category: Standards Track W. Griffin
- SPARTA
- January 2006
-
-
- Using DNS to Securely Publish Secure Shell (SSH) Key Fingerprints
-
-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 a method of verifying Secure Shell (SSH) host
- keys using Domain Name System Security (DNSSEC). The document
- defines a new DNS resource record that contains a standard SSH key
- fingerprint.
-
-Table of Contents
-
- 1. Introduction ....................................................2
- 2. SSH Host Key Verification .......................................2
- 2.1. Method .....................................................2
- 2.2. Implementation Notes .......................................2
- 2.3. Fingerprint Matching .......................................3
- 2.4. Authentication .............................................3
- 3. The SSHFP Resource Record .......................................3
- 3.1. The SSHFP RDATA Format .....................................4
- 3.1.1. Algorithm Number Specification ......................4
- 3.1.2. Fingerprint Type Specification ......................4
- 3.1.3. Fingerprint .........................................5
- 3.2. Presentation Format of the SSHFP RR ........................5
- 4. Security Considerations .........................................5
- 5. IANA Considerations .............................................6
- 6. Normative References ............................................7
- 7. Informational References ........................................7
- 8. Acknowledgements ................................................8
-
-
-
-
-Schlyter & Griffin Standards Track [Page 1]
-\f
-RFC 4255 DNS and SSH Fingerprints January 2006
-
-
-1. Introduction
-
- The SSH [6] protocol provides secure remote login and other secure
- network services over an insecure network. The security of the
- connection relies on the server authenticating itself to the client
- as well as the user authenticating itself to the server.
-
- If a connection is established to a server whose public key is not
- already known to the client, a fingerprint of the key is presented to
- the user for verification. If the user decides that the fingerprint
- is correct and accepts the key, the key is saved locally and used for
- verification for all following connections. While some security-
- conscious users verify the fingerprint out-of-band before accepting
- the key, many users blindly accept the presented key.
-
- The method described here can provide out-of-band verification by
- looking up a fingerprint of the server public key in the DNS [1][2]
- and using DNSSEC [5] to verify the lookup.
-
- In order to distribute the fingerprint using DNS, this document
- defines a new DNS resource record, "SSHFP", to carry the fingerprint.
-
- Basic understanding of the DNS system [1][2] and the DNS security
- extensions [5] is assumed by this document.
-
- 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 [3].
-
-2. SSH Host Key Verification
-
-2.1. Method
-
- Upon connection to an SSH server, the SSH client MAY look up the
- SSHFP resource record(s) for the host it is connecting to. If the
- algorithm and fingerprint of the key received from the SSH server
- match the algorithm and fingerprint of one of the SSHFP resource
- record(s) returned from DNS, the client MAY accept the identity of
- the server.
-
-2.2. Implementation Notes
-
- Client implementors SHOULD provide a configurable policy used to
- select the order of methods used to verify a host key. This document
- defines one method: Fingerprint storage in DNS. Another method
- defined in the SSH Architecture [6] uses local files to store keys
- for comparison. Other methods that could be defined in the future
- might include storing fingerprints in LDAP or other databases. A
-
-
-
-Schlyter & Griffin Standards Track [Page 2]
-\f
-RFC 4255 DNS and SSH Fingerprints January 2006
-
-
- configurable policy will allow administrators to determine which
- methods they want to use and in what order the methods should be
- prioritized. This will allow administrators to determine how much
- trust they want to place in the different methods.
-
- One specific scenario for having a configurable policy is where
- clients do not use fully qualified host names to connect to servers.
- In this scenario, the implementation SHOULD verify the host key
- against a local database before verifying the key via the fingerprint
- returned from DNS. This would help prevent an attacker from
- injecting a DNS search path into the local resolver and forcing the
- client to connect to a different host.
-
-2.3. Fingerprint Matching
-
- The public key and the SSHFP resource record are matched together by
- comparing algorithm number and fingerprint.
-
- The public key algorithm and the SSHFP algorithm number MUST
- match.
-
- A message digest of the public key, using the message digest
- algorithm specified in the SSHFP fingerprint type, MUST match the
- SSHFP fingerprint.
-
-2.4. Authentication
-
- A public key verified using this method MUST NOT be trusted if the
- SSHFP resource record (RR) used for verification was not
- authenticated by a trusted SIG RR.
-
- Clients that do validate the DNSSEC signatures themselves SHOULD use
- standard DNSSEC validation procedures.
-
- Clients that do not validate the DNSSEC signatures themselves MUST
- use a secure transport (e.g., TSIG [9], SIG(0) [10], or IPsec [8])
- between themselves and the entity performing the signature
- validation.
-
-3. The SSHFP Resource Record
-
- The SSHFP resource record (RR) is used to store a fingerprint of an
- SSH public host key that is associated with a Domain Name System
- (DNS) name.
-
- The RR type code for the SSHFP RR is 44.
-
-
-
-
-
-Schlyter & Griffin Standards Track [Page 3]
-\f
-RFC 4255 DNS and SSH Fingerprints January 2006
-
-
-3.1. The SSHFP RDATA Format
-
- The RDATA for a SSHFP RR consists of an algorithm number, fingerprint
- type and the fingerprint of the public host key.
-
- 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
- +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
- | algorithm | fp type | /
- +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ /
- / /
- / fingerprint /
- / /
- +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
-
-3.1.1. Algorithm Number Specification
-
- This algorithm number octet describes the algorithm of the public
- key. The following values are assigned:
-
- Value Algorithm name
- ----- --------------
- 0 reserved
- 1 RSA
- 2 DSS
-
- Reserving other types requires IETF consensus [4].
-
-3.1.2. Fingerprint Type Specification
-
- The fingerprint type octet describes the message-digest algorithm
- used to calculate the fingerprint of the public key. The following
- values are assigned:
-
- Value Fingerprint type
- ----- ----------------
- 0 reserved
- 1 SHA-1
-
- Reserving other types requires IETF consensus [4].
-
- For interoperability reasons, as few fingerprint types as possible
- should be reserved. The only reason to reserve additional types is
- to increase security.
-
-
-
-
-
-
-
-Schlyter & Griffin Standards Track [Page 4]
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-RFC 4255 DNS and SSH Fingerprints January 2006
-
-
-3.1.3. Fingerprint
-
- The fingerprint is calculated over the public key blob as described
- in [7].
-
- The message-digest algorithm is presumed to produce an opaque octet
- string output, which is placed as-is in the RDATA fingerprint field.
-
-3.2. Presentation Format of the SSHFP RR
-
- The RDATA of the presentation format of the SSHFP resource record
- consists of two numbers (algorithm and fingerprint type) followed by
- the fingerprint itself, presented in hex, e.g.:
-
- host.example. SSHFP 2 1 123456789abcdef67890123456789abcdef67890
-
- The use of mnemonics instead of numbers is not allowed.
-
-4. Security Considerations
-
- Currently, the amount of trust a user can realistically place in a
- server key is proportional to the amount of attention paid to
- verifying that the public key presented actually corresponds to the
- private key of the server. If a user accepts a key without verifying
- the fingerprint with something learned through a secured channel, the
- connection is vulnerable to a man-in-the-middle attack.
-
- The overall security of using SSHFP for SSH host key verification is
- dependent on the security policies of the SSH host administrator and
- DNS zone administrator (in transferring the fingerprint), detailed
- aspects of how verification is done in the SSH implementation, and in
- the client's diligence in accessing the DNS in a secure manner.
-
- One such aspect is in which order fingerprints are looked up (e.g.,
- first checking local file and then SSHFP). We note that, in addition
- to protecting the first-time transfer of host keys, SSHFP can
- optionally be used for stronger host key protection.
-
- If SSHFP is checked first, new SSH host keys may be distributed by
- replacing the corresponding SSHFP in DNS.
-
- If SSH host key verification can be configured to require SSHFP,
- SSH host key revocation can be implemented by removing the
- corresponding SSHFP from DNS.
-
-
-
-
-
-
-
-Schlyter & Griffin Standards Track [Page 5]
-\f
-RFC 4255 DNS and SSH Fingerprints January 2006
-
-
- As stated in Section 2.2, we recommend that SSH implementors provide
- a policy mechanism to control the order of methods used for host key
- verification. One specific scenario for having a configurable policy
- is where clients use unqualified host names to connect to servers.
- In this case, we recommend that SSH implementations check the host
- key against a local database before verifying the key via the
- fingerprint returned from DNS. This would help prevent an attacker
- from injecting a DNS search path into the local resolver and forcing
- the client to connect to a different host.
-
- A different approach to solve the DNS search path issue would be for
- clients to use a trusted DNS search path, i.e., one not acquired
- through DHCP or other autoconfiguration mechanisms. Since there is
- no way with current DNS lookup APIs to tell whether a search path is
- from a trusted source, the entire client system would need to be
- configured with this trusted DNS search path.
-
- Another dependency is on the implementation of DNSSEC itself. As
- stated in Section 2.4, we mandate the use of secure methods for
- lookup and that SSHFP RRs are authenticated by trusted SIG RRs. This
- is especially important if SSHFP is to be used as a basis for host
- key rollover and/or revocation, as described above.
-
- Since DNSSEC only protects the integrity of the host key fingerprint
- after it is signed by the DNS zone administrator, the fingerprint
- must be transferred securely from the SSH host administrator to the
- DNS zone administrator. This could be done manually between the
- administrators or automatically using secure DNS dynamic update [11]
- between the SSH server and the nameserver. We note that this is no
- different from other key enrollment situations, e.g., a client
- sending a certificate request to a certificate authority for signing.
-
-5. IANA Considerations
-
- IANA has allocated the RR type code 44 for SSHFP from the standard RR
- type space.
-
- IANA has opened a new registry for the SSHFP RR type for public key
- algorithms. The defined types are:
-
- 0 is reserved
- 1 is RSA
- 2 is DSA
-
- Adding new reservations requires IETF consensus [4].
-
-
-
-
-
-
-Schlyter & Griffin Standards Track [Page 6]
-\f
-RFC 4255 DNS and SSH Fingerprints January 2006
-
-
- IANA has opened a new registry for the SSHFP RR type for fingerprint
- types. The defined types are:
-
- 0 is reserved
- 1 is SHA-1
-
- Adding new reservations requires IETF consensus [4].
-
-6. 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] Narten, T. and H. Alvestrand, "Guidelines for Writing an IANA
- Considerations Section in RFCs", BCP 26, RFC 2434, October
- 1998.
-
- [5] Arends, R., Austein, R., Larson, M., Massey, D., and S. Rose,
- "DNS Security Introduction and Requirements", RFC 4033, March
- 2005.
-
- Arends, R., Austein, R., Larson, M., Massey, D., and S. Rose,
- "Resource Records for the DNS Security Extensions", RFC 4034,
- March 2005.
-
- Arends, R., Austein, R., Larson, M., Massey, D., and S. Rose,
- "Protocol Modifications for the DNS Security Extensions", RFC
- 4035, March 2005.
-
- [6] Ylonen, T. and C. Lonvick, Ed., "The Secure Shell (SSH)
- Protocol Architecture", RFC 4251, January 2006.
-
- [7] Ylonen, T. and C. Lonvick, Ed., "The Secure Shell (SSH)
- Transport Layer Protocol", RFC 4253, January 2006.
-
-7. Informational References
-
- [8] Thayer, R., Doraswamy, N., and R. Glenn, "IP Security Document
- Roadmap", RFC 2411, November 1998.
-
-
-
-
-
-
-Schlyter & Griffin Standards Track [Page 7]
-\f
-RFC 4255 DNS and SSH Fingerprints January 2006
-
-
- [9] Vixie, P., Gudmundsson, O., Eastlake 3rd, D., and B.
- Wellington, "Secret Key Transaction Authentication for DNS
- (TSIG)", RFC 2845, May 2000.
-
- [10] Eastlake 3rd, D., "DNS Request and Transaction Signatures
- ( SIG(0)s )", RFC 2931, September 2000.
-
- [11] Wellington, B., "Secure Domain Name System (DNS) Dynamic
- Update", RFC 3007, November 2000.
-
-8. Acknowledgements
-
- The authors gratefully acknowledge, in no particular order, the
- contributions of the following persons:
-
- Martin Fredriksson
-
- Olafur Gudmundsson
-
- Edward Lewis
-
- Bill Sommerfeld
-
-Authors' Addresses
-
- Jakob Schlyter
- OpenSSH
- 812 23rd Avenue SE
- Calgary, Alberta T2G 1N8
- Canada
-
- EMail: jakob@openssh.com
- URI: http://www.openssh.com/
-
-
- Wesley Griffin
- SPARTA
- 7075 Samuel Morse Drive
- Columbia, MD 21046
- USA
-
- EMail: wgriffin@sparta.com
- URI: http://www.sparta.com/
-
-
-
-
-
-
-
-
-Schlyter & Griffin Standards Track [Page 8]
-\f
-RFC 4255 DNS and SSH Fingerprints January 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).
-
-
-
-
-
-
-
-Schlyter & Griffin Standards Track [Page 9]
-\f
+++ /dev/null
-
-
-
-
-
-
-Network Working Group D. Eastlake 3rd
-Request for Comments: 4343 Motorola Laboratories
-Updates: 1034, 1035, 2181 January 2006
-Category: Standards Track
-
-
- Domain Name System (DNS) Case Insensitivity Clarification
-
-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
-
- Domain Name System (DNS) names are "case insensitive". This document
- explains exactly what that means and provides a clear specification
- of the rules. This clarification updates RFCs 1034, 1035, and 2181.
-
-Table of Contents
-
- 1. Introduction ....................................................2
- 2. Case Insensitivity of DNS Labels ................................2
- 2.1. Escaping Unusual DNS Label Octets ..........................2
- 2.2. Example Labels with Escapes ................................3
- 3. Name Lookup, Label Types, and CLASS .............................3
- 3.1. Original DNS Label Types ...................................4
- 3.2. Extended Label Type Case Insensitivity Considerations ......4
- 3.3. CLASS Case Insensitivity Considerations ....................4
- 4. Case on Input and Output ........................................5
- 4.1. DNS Output Case Preservation ...............................5
- 4.2. DNS Input Case Preservation ................................5
- 5. Internationalized Domain Names ..................................6
- 6. Security Considerations .........................................6
- 7. Acknowledgements ................................................7
- Normative References................................................7
- Informative References..............................................8
-
-
-
-
-
-
-
-Eastlake 3rd Standards Track [Page 1]
-\f
-RFC 4343 DNS Case Insensitivity Clarification January 2006
-
-
-1. Introduction
-
- The Domain Name System (DNS) is the global hierarchical replicated
- distributed database system for Internet addressing, mail proxy, and
- other information. Each node in the DNS tree has a name consisting
- of zero or more labels [STD13, RFC1591, RFC2606] that are treated in
- a case insensitive fashion. This document clarifies the meaning of
- "case insensitive" for the DNS. This clarification updates RFCs
- 1034, 1035 [STD13], and [RFC2181].
-
- 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].
-
-2. Case Insensitivity of DNS Labels
-
- DNS was specified in the era of [ASCII]. DNS names were expected to
- look like most host names or Internet email address right halves (the
- part after the at-sign, "@") or to be numeric, as in the in-addr.arpa
- part of the DNS name space. For example,
-
- foo.example.net.
- aol.com.
- www.gnu.ai.mit.edu.
- or 69.2.0.192.in-addr.arpa.
-
- Case-varied alternatives to the above [RFC3092] would be DNS names
- like
-
- Foo.ExamplE.net.
- AOL.COM.
- WWW.gnu.AI.mit.EDU.
- or 69.2.0.192.in-ADDR.ARPA.
-
- However, the individual octets of which DNS names consist are not
- limited to valid ASCII character codes. They are 8-bit bytes, and
- all values are allowed. Many applications, however, interpret them
- as ASCII characters.
-
-2.1. Escaping Unusual DNS Label Octets
-
- In Master Files [STD13] and other human-readable and -writable ASCII
- contexts, an escape is needed for the byte value for period (0x2E,
- ".") and all octet values outside of the inclusive range from 0x21
- ("!") to 0x7E ("~"). That is to say, 0x2E and all octet values in
- the two inclusive ranges from 0x00 to 0x20 and from 0x7F to 0xFF.
-
-
-
-
-
-Eastlake 3rd Standards Track [Page 2]
-\f
-RFC 4343 DNS Case Insensitivity Clarification January 2006
-
-
- One typographic convention for octets that do not correspond to an
- ASCII printing graphic is to use a back-slash followed by the value
- of the octet as an unsigned integer represented by exactly three
- decimal digits.
-
- The same convention can be used for printing ASCII characters so that
- they will be treated as a normal label character. This includes the
- back-slash character used in this convention itself, which can be
- expressed as \092 or \\, and the special label separator period
- ("."), which can be expressed as and \046 or \. It is advisable to
- avoid using a backslash to quote an immediately following non-
- printing ASCII character code to avoid implementation difficulties.
-
- A back-slash followed by only one or two decimal digits is undefined.
- A back-slash followed by four decimal digits produces two octets, the
- first octet having the value of the first three digits considered as
- a decimal number, and the second octet being the character code for
- the fourth decimal digit.
-
-2.2. Example Labels with Escapes
-
- The first example below shows embedded spaces and a period (".")
- within a label. The second one shows a 5-octet label where the
- second octet has all bits zero, the third is a backslash, and the
- fourth octet has all bits one.
-
- Donald\032E\.\032Eastlake\0323rd.example.
- and a\000\\\255z.example.
-
-3. Name Lookup, Label Types, and CLASS
-
- According to the original DNS design decision, comparisons on name
- lookup for DNS queries should be case insensitive [STD13]. That is
- to say, a lookup string octet with a value in the inclusive range
- from 0x41 to 0x5A, the uppercase ASCII letters, MUST match the
- identical value and also match the corresponding value in the
- inclusive range from 0x61 to 0x7A, the lowercase ASCII letters. A
- lookup string octet with a lowercase ASCII letter value MUST
- similarly match the identical value and also match the corresponding
- value in the uppercase ASCII letter range.
-
- (Historical note: The terms "uppercase" and "lowercase" were invented
- after movable type. The terms originally referred to the two font
- trays for storing, in partitioned areas, the different physical type
- elements. Before movable type, the nearest equivalent terms were
- "majuscule" and "minuscule".)
-
-
-
-
-
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-
-
- One way to implement this rule would be to subtract 0x20 from all
- octets in the inclusive range from 0x61 to 0x7A before comparing
- octets. Such an operation is commonly known as "case folding", but
- implementation via case folding is not required. Note that the DNS
- case insensitivity does NOT correspond to the case folding specified
- in [ISO-8859-1] or [ISO-8859-2]. For example, the octets 0xDD (\221)
- and 0xFD (\253) do NOT match, although in other contexts, where they
- are interpreted as the upper- and lower-case version of "Y" with an
- acute accent, they might.
-
-3.1. Original DNS Label Types
-
- DNS labels in wire-encoded names have a type associated with them.
- The original DNS standard [STD13] had only two types: ASCII labels,
- with a length from zero to 63 octets, and indirect (or compression)
- labels, which consist of an offset pointer to a name location
- elsewhere in the wire encoding on a DNS message. (The ASCII label of
- length zero is reserved for use as the name of the root node of the
- name tree.) ASCII labels follow the ASCII case conventions described
- herein and, as stated above, can actually contain arbitrary byte
- values. Indirect labels are, in effect, replaced by the name to
- which they point, which is then treated with the case insensitivity
- rules in this document.
-
-3.2. Extended Label Type Case Insensitivity Considerations
-
- DNS was extended by [RFC2671] so that additional label type numbers
- would be available. (The only such type defined so far is the BINARY
- type [RFC2673], which is now Experimental [RFC3363].)
-
- The ASCII case insensitivity conventions only apply to ASCII labels;
- that is to say, label type 0x0, whether appearing directly or invoked
- by indirect labels.
-
-3.3. CLASS Case Insensitivity Considerations
-
- As described in [STD13] and [RFC2929], DNS has an additional axis for
- data location called CLASS. The only CLASS in global use at this
- time is the "IN" (Internet) CLASS.
-
- The handling of DNS label case is not CLASS dependent. With the
- original design of DNS, it was intended that a recursive DNS resolver
- be able to handle new CLASSes that were unknown at the time of its
- implementation. This requires uniform handling of label case
- insensitivity. Should it become desirable, for example, to allocate
- a CLASS with "case sensitive ASCII labels", it would be necessary to
- allocate a new label type for these labels.
-
-
-
-
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-
-
-4. Case on Input and Output
-
- While ASCII label comparisons are case insensitive, [STD13] says case
- MUST be preserved on output and preserved when convenient on input.
- However, this means less than it would appear, since the preservation
- of case on output is NOT required when output is optimized by the use
- of indirect labels, as explained below.
-
-4.1. DNS Output Case Preservation
-
- [STD13] views the DNS namespace as a node tree. ASCII output is as
- if a name were marshaled by taking the label on the node whose name
- is to be output, converting it to a typographically encoded ASCII
- string, walking up the tree outputting each label encountered, and
- preceding all labels but the first with a period ("."). Wire output
- follows the same sequence, but each label is wire encoded, and no
- periods are inserted. No "case conversion" or "case folding" is done
- during such output operations, thus "preserving" case. However, to
- optimize output, indirect labels may be used to point to names
- elsewhere in the DNS answer. In determining whether the name to be
- pointed to (for example, the QNAME) is the "same" as the remainder of
- the name being optimized, the case insensitive comparison specified
- above is done. Thus, such optimization may easily destroy the output
- preservation of case. This type of optimization is commonly called
- "name compression".
-
-4.2. DNS Input Case Preservation
-
- Originally, DNS data came from an ASCII Master File as defined in
- [STD13] or a zone transfer. DNS Dynamic update and incremental zone
- transfers [RFC1995] have been added as a source of DNS data [RFC2136,
- RFC3007]. When a node in the DNS name tree is created by any of such
- inputs, no case conversion is done. Thus, the case of ASCII labels
- is preserved if they are for nodes being created. However, when a
- name label is input for a node that already exists in DNS data being
- held, the situation is more complex. Implementations are free to
- retain the case first loaded for such a label, to allow new input to
- override the old case, or even to maintain separate copies preserving
- the input case.
-
- For example, if data with owner name "foo.bar.example" [RFC3092] is
- loaded and then later data with owner name "xyz.BAR.example" is
- input, the name of the label on the "bar.example" node (i.e., "bar")
- might or might not be changed to "BAR" in the DNS stored data. Thus,
- later retrieval of data stored under "xyz.bar.example" in this case
- can use "xyz.BAR.example" in all returned data, use "xyz.bar.example"
- in all returned data, or even, when more than one RR is being
- returned, use a mixture of these two capitalizations. This last case
-
-
-
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-
-
- is unlikely, as optimization of answer length through indirect labels
- tends to cause only one copy of the name tail ("bar.example" or
- "BAR.example") to be used for all returned RRs. Note that none of
- this has any effect on the number or completeness of the RR set
- returned, only on the case of the names in the RR set returned.
-
- The same considerations apply when inputting multiple data records
- with owner names differing only in case. For example, if an "A"
- record is the first resource record stored under owner name
- "xyz.BAR.example" and then a second "A" record is stored under
- "XYZ.BAR.example", the second MAY be stored with the first (lower
- case initial label) name, the second MAY override the first so that
- only an uppercase initial label is retained, or both capitalizations
- MAY be kept in the DNS stored data. In any case, a retrieval with
- either capitalization will retrieve all RRs with either
- capitalization.
-
- Note that the order of insertion into a server database of the DNS
- name tree nodes that appear in a Master File is not defined so that
- the results of inconsistent capitalization in a Master File are
- unpredictable output capitalization.
-
-5. Internationalized Domain Names
-
- A scheme has been adopted for "internationalized domain names" and
- "internationalized labels" as described in [RFC3490, RFC3454,
- RFC3491, and RFC3492]. It makes most of [UNICODE] available through
- a separate application level transformation from internationalized
- domain name to DNS domain name and from DNS domain name to
- internationalized domain name. Any case insensitivity that
- internationalized domain names and labels have varies depending on
- the script and is handled entirely as part of the transformation
- described in [RFC3454] and [RFC3491], which should be seen for
- further details. This is not a part of the DNS as standardized in
- STD 13.
-
-6. Security Considerations
-
- The equivalence of certain DNS label types with case differences, as
- clarified in this document, can lead to security problems. For
- example, a user could be confused by believing that two domain names
- differing only in case were actually different names.
-
- Furthermore, a domain name may be used in contexts other than the
- DNS. It could be used as a case sensitive index into some database
- or file system. Or it could be interpreted as binary data by some
- integrity or authentication code system. These problems can usually
- be handled by using a standardized or "canonical" form of the DNS
-
-
-
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-RFC 4343 DNS Case Insensitivity Clarification January 2006
-
-
- ASCII type labels; that is, always mapping the ASCII letter value
- octets in ASCII labels to some specific pre-chosen case, either
- uppercase or lower case. An example of a canonical form for domain
- names (and also a canonical ordering for them) appears in Section 6
- of [RFC4034]. See also [RFC3597].
-
- Finally, a non-DNS name may be stored into DNS with the false
- expectation that case will always be preserved. For example,
- although this would be quite rare, on a system with case sensitive
- email address local parts, an attempt to store two Responsible Person
- (RP) [RFC1183] records that differed only in case would probably
- produce unexpected results that might have security implications.
- That is because the entire email address, including the possibly case
- sensitive local or left-hand part, is encoded into a DNS name in a
- readable fashion where the case of some letters might be changed on
- output as described above.
-
-7. Acknowledgements
-
- The contributions to this document by Rob Austein, Olafur
- Gudmundsson, Daniel J. Anderson, Alan Barrett, Marc Blanchet, Dana,
- Andreas Gustafsson, Andrew Main, Thomas Narten, and Scott Seligman
- are gratefully acknowledged.
-
-Normative References
-
- [ASCII] ANSI, "USA Standard Code for Information Interchange",
- X3.4, American National Standards Institute: New York,
- 1968.
-
- [RFC1995] Ohta, M., "Incremental Zone Transfer in DNS", RFC 1995,
- August 1996.
-
- [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
- Requirement Levels", BCP 14, RFC 2119, March 1997.
-
- [RFC2136] Vixie, P., Thomson, S., Rekhter, Y., and J. Bound,
- "Dynamic Updates in the Domain Name System (DNS
- UPDATE)", RFC 2136, April 1997.
-
- [RFC2181] Elz, R. and R. Bush, "Clarifications to the DNS
- Specification", RFC 2181, July 1997.
-
- [RFC3007] Wellington, B., "Secure Domain Name System (DNS) Dynamic
- Update", RFC 3007, November 2000.
-
-
-
-
-
-
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-RFC 4343 DNS Case Insensitivity Clarification January 2006
-
-
- [RFC3597] Gustafsson, A., "Handling of Unknown DNS Resource Record
- (RR) Types", RFC 3597, September 2003.
-
- [RFC4034] Arends, R., Austein, R., Larson, M., Massey, D., and S.
- Rose, "Resource Records for the DNS Security
- Extensions", RFC 4034, March 2005.
-
- [STD13] Mockapetris, P., "Domain names - concepts and
- facilities", STD 13, RFC 1034, November 1987.
-
- Mockapetris, P., "Domain names - implementation and
- specification", STD 13, RFC 1035, November 1987.
-
-Informative References
-
- [ISO-8859-1] International Standards Organization, Standard for
- Character Encodings, Latin-1.
-
- [ISO-8859-2] International Standards Organization, Standard for
- Character Encodings, Latin-2.
-
- [RFC1183] Everhart, C., Mamakos, L., Ullmann, R., and P.
- Mockapetris, "New DNS RR Definitions", RFC 1183, October
- 1990.
-
- [RFC1591] Postel, J., "Domain Name System Structure and
- Delegation", RFC 1591, March 1994.
-
- [RFC2606] Eastlake 3rd, D. and A. Panitz, "Reserved Top Level DNS
- Names", BCP 32, RFC 2606, June 1999.
-
- [RFC2929] Eastlake 3rd, D., Brunner-Williams, E., and B. Manning,
- "Domain Name System (DNS) IANA Considerations", BCP 42,
- RFC 2929, September 2000.
-
- [RFC2671] Vixie, P., "Extension Mechanisms for DNS (EDNS0)", RFC
- 2671, August 1999.
-
- [RFC2673] Crawford, M., "Binary Labels in the Domain Name System",
- RFC 2673, August 1999.
-
- [RFC3092] Eastlake 3rd, D., Manros, C., and E. Raymond, "Etymology
- of "Foo"", RFC 3092, 1 April 2001.
-
- [RFC3363] Bush, R., Durand, A., Fink, B., Gudmundsson, O., and T.
- Hain, "Representing Internet Protocol version 6 (IPv6)
- Addresses in the Domain Name System (DNS)", RFC 3363,
- August 2002.
-
-
-
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-
-
- [RFC3454] Hoffman, P. and M. Blanchet, "Preparation of
- Internationalized Strings ("stringprep")", RFC 3454,
- December 2002.
-
- [RFC3490] Faltstrom, P., Hoffman, P., and A. Costello,
- "Internationalizing Domain Names in Applications
- (IDNA)", RFC 3490, March 2003.
-
- [RFC3491] Hoffman, P. and M. Blanchet, "Nameprep: A Stringprep
- Profile for Internationalized Domain Names (IDN)", RFC
- 3491, March 2003.
-
- [RFC3492] Costello, A., "Punycode: A Bootstring encoding of
- Unicode for Internationalized Domain Names in
- Applications (IDNA)", RFC 3492, March 2003.
-
- [UNICODE] The Unicode Consortium, "The Unicode Standard",
- <http://www.unicode.org/unicode/standard/standard.html>.
-
-Author's Address
-
- Donald E. Eastlake 3rd
- Motorola Laboratories
- 155 Beaver Street
- Milford, MA 01757 USA
-
- Phone: +1 508-786-7554 (w)
- EMail: Donald.Eastlake@motorola.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
- 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 Standards Track [Page 10]
-\f
+++ /dev/null
-
-
-
-
-
-
-Network Working Group J. Rosenberg, Ed.
-Request for Comments: 4367 IAB
-Category: Informational February 2006
-
-
- What's in a Name: False Assumptions about DNS Names
-
-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 Domain Name System (DNS) provides an essential service on the
- Internet, mapping structured names to a variety of data, usually IP
- addresses. These names appear in email addresses, Uniform Resource
- Identifiers (URIs), and other application-layer identifiers that are
- often rendered to human users. Because of this, there has been a
- strong demand to acquire names that have significance to people,
- through equivalence to registered trademarks, company names, types of
- services, and so on. There is a danger in this trend; the humans and
- automata that consume and use such names will associate specific
- semantics with some names and thereby make assumptions about the
- services that are, or should be, provided by the hosts associated
- with the names. Those assumptions can often be false, resulting in a
- variety of failure conditions. This document discusses this problem
- in more detail and makes recommendations on how it can be avoided.
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-Rosenberg Informational [Page 1]
-\f
-RFC 4367 Name Assumptions February 2006
-
-
-Table of Contents
-
- 1. Introduction ....................................................2
- 2. Target Audience .................................................4
- 3. Modeling Usage of the DNS .......................................4
- 4. Possible Assumptions ............................................5
- 4.1. By the User ................................................5
- 4.2. By the Client ..............................................6
- 4.3. By the Server ..............................................7
- 5. Consequences of False Assumptions ...............................8
- 6. Reasons Why the Assumptions Can Be False ........................9
- 6.1. Evolution ..................................................9
- 6.2. Leakage ...................................................10
- 6.3. Sub-Delegation ............................................10
- 6.4. Mobility ..................................................12
- 6.5. Human Error ...............................................12
- 7. Recommendations ................................................12
- 8. A Note on RFC 2219 and RFC 2782 ................................13
- 9. Security Considerations ........................................14
- 10. Acknowledgements ..............................................14
- 11. IAB Members ...................................................14
- 12. Informative References ........................................15
-
-1. Introduction
-
- The Domain Name System (DNS) [1] provides an essential service on the
- Internet, mapping structured names to a variety of different types of
- data. Most often it is used to obtain the IP address of a host
- associated with that name [2] [1] [3]. However, it can be used to
- obtain other information, and proposals have been made for nearly
- everything, including geographic information [4].
-
- Domain names are most often used in identifiers used by application
- protocols. The most well known include email addresses and URIs,
- such as the HTTP URL [5], Real Time Streaming Protocol (RTSP) URL
- [6], and SIP URI [7]. These identifiers are ubiquitous, appearing on
- business cards, web pages, street signs, and so on. Because of this,
- there has been a strong demand to acquire domain names that have
- significance to people through equivalence to registered trademarks,
- company names, types of services, and so on. Such identifiers serve
- many business purposes, including extension of brand, advertising,
- and so on.
-
- People often make assumptions about the type of service that is or
- should be provided by a host associated with that name, based on
- their expectations and understanding of what the name implies. This,
- in turn, triggers attempts by organizations to register domain names
- based on that presumed user expectation. Examples of this are the
-
-
-
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-\f
-RFC 4367 Name Assumptions February 2006
-
-
- various proposals for a Top-Level Domain (TLD) that could be
- associated with adult content [8], the requests for creation of TLDs
- associated with mobile devices and services, and even phishing
- attacks.
-
- When these assumptions are codified into the behavior of an
- automaton, such as an application client or server, as a result of
- implementor choice, management directive, or domain owner policy, the
- overall system can fail in various ways. This document describes a
- number of typical ways in which these assumptions can be codified,
- how they can be wrong, the consequences of those mistakes, and the
- recommended ways in which they can be avoided.
-
- Section 4 describes some of the possible assumptions that clients,
- servers, and people can make about a domain name. In this context,
- an "assumption" is defined as any behavior that is expected when
- accessing a service at a domain name, even though the behavior is not
- explicitly codified in protocol specifications. Frequently, these
- assumptions involve ignoring parts of a specification based on an
- assumption that the client or server is deployed in an environment
- that is more rigid than the specification allows. Section 5
- overviews some of the consequences of these false assumptions.
- Generally speaking, these consequences can include a variety of
- different interoperability failures, user experience failures, and
- system failures. Section 6 discusses why these assumptions can be
- false from the very beginning or become false at some point in the
- future. Most commonly, they become false because the environment
- changes in unexpected ways over time, and what was a valid assumption
- before, no longer is. Other times, the assumptions prove wrong
- because they were based on the belief that a specific community of
- clients and servers was participating, and an element outside of that
- community began participating.
-
- Section 7 then provides some recommendations. These recommendations
- encapsulate some of the engineering mantras that have been at the
- root of Internet protocol design for decades. These include:
-
- Follow the specifications.
-
- Use the capability negotiation techniques provided in the
- protocols.
-
- Be liberal in what you accept, and conservative in what you send.
- [18]
-
- Overall, automata should not change their behavior within a protocol
- based on the domain name, or some component of the domain name, of
- the host they are communicating with.
-
-
-
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-\f
-RFC 4367 Name Assumptions February 2006
-
-
-2. Target Audience
-
- This document has several audiences. Firstly, it is aimed at
- implementors who ultimately develop the software that make the false
- assumptions that are the subject of this document. The
- recommendations described here are meant to reinforce the engineering
- guidelines that are often understood by implementors, but frequently
- forgotten as deadlines near and pressures mount.
-
- The document is also aimed at technology managers, who often develop
- the requirements that lead to these false assumptions. For them,
- this document serves as a vehicle for emphasizing the importance of
- not taking shortcuts in the scope of applicability of a project.
-
- Finally, this document is aimed at domain name policy makers and
- administrators. For them, it points out the perils in establishing
- domain policies that get codified into the operation of applications
- running within that domain.
-
-3. Modeling Usage of the DNS
-
-
- +--------+
- | |
- | |
- | DNS |
- |Service |
- | |
- +--------+
- ^ |
- | |
- | |
- | |
- /--\ | |
- | | | V
- | | +--------+ +--------+
- \--/ | | | |
- | | | | |
- ---+--- | Client |-------------------->| Server |
- | | | | |
- | | | | |
- /\ +--------+ +--------+
- / \
- / \
-
- User
- Figure 1
-
-
-
-
-Rosenberg Informational [Page 4]
-\f
-RFC 4367 Name Assumptions February 2006
-
-
- Figure 1 shows a simple conceptual model of how the DNS is used by
- applications. A user of the application obtains an identifier for
- particular content or service it wishes to obtain. This identifier
- is often a URL or URI that contains a domain name. The user enters
- this identifier into its client application (for example, by typing
- in the URL in a web browser window). The client is the automaton (a
- software and/or hardware system) that contacts a server for that
- application in order to provide service to the user. To do that, it
- contacts a DNS server to resolve the domain name in the identifier to
- an IP address. It then contacts the server at that IP address. This
- simple model applies to application protocols such as HTTP [5], SIP
- [7], RTSP [6], and SMTP [9].
-
- >From this model, it is clear that three entities in the system can
- potentially make false assumptions about the service provided by the
- server. The human user may form expectations relating to the content
- of the service based on a parsing of the host name from which the
- content originated. The server might assume that the client
- connecting to it supports protocols that it does not, can process
- content that it cannot, or has capabilities that it does not.
- Similarly, the client might assume that the server supports
- protocols, content, or capabilities that it does not. Furthermore,
- applications can potentially contain a multiplicity of humans,
- clients, and servers, all of which can independently make these false
- assumptions.
-
-4. Possible Assumptions
-
- For each of the three elements, there are many types of false
- assumptions that can be made.
-
-4.1. By the User
-
- The set of possible assumptions here is nearly boundless. Users
- might assume that an HTTP URL that looks like a company name maps to
- a server run by that company. They might assume that an email from a
- email address in the .gov TLD is actually from a government employee.
- They might assume that the content obtained from a web server within
- a TLD labeled as containing adult materials (for example, .sex)
- actually contains adult content [8]. These assumptions are
- unavoidable, may all be false, and are not the focus of this
- document.
-
-
-
-
-
-
-
-
-
-Rosenberg Informational [Page 5]
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-RFC 4367 Name Assumptions February 2006
-
-
-4.2. By the Client
-
- Even though the client is an automaton, it can make some of the same
- assumptions that a human user might make. For example, many clients
- assume that any host with a hostname that begins with "www" is a web
- server, even though this assumption may be false.
-
- In addition, the client concerns itself with the protocols needed to
- communicate with the server. As a result, it might make assumptions
- about the operation of the protocols for communicating with the
- server. These assumptions manifest themselves in an implementation
- when a standardized protocol negotiation technique defined by the
- protocol is ignored, and instead, some kind of rule is coded into the
- software that comes to its own conclusion about what the negotiation
- would have determined. The result is often a loss of
- interoperability, degradation in reliability, and worsening of user
- experience.
-
- Authentication Algorithm: Though a protocol might support a
- multiplicity of authentication techniques, a client might assume
- that a server always supports one that is only optional according
- to the protocol. For example, a SIP client contacting a SIP
- server in a domain that is apparently used to identify mobile
- devices (for example, www.example.cellular) might assume that the
- server supports the optional Authentication and Key Agreement
- (AKA) digest technique [10], just because of the domain name that
- was used to access the server. As another example, a web client
- might assume that a server with the name https.example.com
- supports HTTP over Transport Layer Security (TLS) [16].
-
- Data Formats: Though a protocol might allow a multiplicity of data
- formats to be sent from the server to the client, the client might
- assume a specific one, rather than using the content labeling and
- negotiation capabilities of the underlying protocol. For example,
- an RTSP client might assume that all audio content delivered to it
- from media.example.cellular uses a low-bandwidth codec. As
- another example, a mail client might assume that the contents of
- messages it retrieves from a mail server at mail.example.cellular
- are always text, instead of checking the MIME headers [11] in the
- message in order to determine the actual content type.
-
- Protocol Extensions: A client may attempt an operation on the server
- that requires the server to support an optional protocol
- extension. However, rather than implementing the necessary
- fallback logic, the client may falsely assume that the extension
- is supported. As an example, a SIP client that requires reliable
- provisional responses to its request (RFC 3262 [17]) might assume
- that this extension is supported on servers in the domain
-
-
-
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-
- sip.example.telecom. Furthermore, the client would not implement
- the fallback behavior defined in RFC 3262, since it would assume
- that all servers it will communicate with are in this domain and
- that all therefore support this extension. However, if the
- assumptions prove wrong, the client is unable to make any phone
- calls.
-
- Languages: A client may support facilities for processing text
- content differently depending on the language of the text. Rather
- than determining the language from markers in the message from the
- server, the client might assume a language based on the domain
- name. This assumption can easily be wrong. For example, a client
- might assume that any text in a web page retrieved from a server
- within the .de country code TLD (ccTLD) is in German, and attempt
- a translation to Finnish. This would fail dramatically if the
- text was actually in French. Unfortunately, this client behavior
- is sometimes exhibited because the server has not properly labeled
- the language of the content in the first place, often because the
- server assumed such a labeling was not needed. This is an example
- of how these false assumptions can create vicious cycles.
-
-4.3. By the Server
-
- The server, like the client, is an automaton. Let us consider one
- servicing a particular domain -- www.company.cellular, for example.
- It might assume that all clients connecting to this domain support
- particular capabilities, rather than using the underlying protocol to
- make this determination. Some examples include:
-
- Authentication Algorithm: The server can assume that a client
- supports a particular, optional, authentication technique, and it
- therefore does not support the mandatory one.
-
- Language: The server can serve content in a particular language,
- based on an assumption that clients accessing the domain speak a
- particular language, or based on an assumption that clients coming
- from a particular IP address speak a certain language.
-
- Data Formats: The server can assume that the client supports a
- particular set of MIME types and is only capable of sending ones
- within that set. When it generates content in a protocol
- response, it ignores any content negotiation headers that were
- present in the request. For example, a web server might ignore
- the Accept HTTP header field and send a specific image format.
-
-
-
-
-
-
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-
- Protocol Extensions: The server might assume that the client supports
- a particular optional protocol extension, and so it does not
- support the fallback behavior necessary in the case where the
- client does not.
-
- Client Characteristics: The server might assume certain things about
- the physical characteristics of its clients, such as memory
- footprint, processing power, screen sizes, screen colors, pointing
- devices, and so on. Based on these assumptions, it might choose
- specific behaviors when processing a request. For example, a web
- server might always assume that clients connect through cell
- phones, and therefore return content that lacks images and is
- tuned for such devices.
-
-5. Consequences of False Assumptions
-
- There are numerous negative outcomes that can arise from the various
- false assumptions that users, servers, and clients can make. These
- include:
-
- Interoperability Failure: In these cases, the client or server
- assumed some kind of protocol operation, and this assumption was
- wrong. The result is that the two are unable to communicate, and
- the user receives some kind of an error. This represents a total
- interoperability failure, manifesting itself as a lack of service
- to users of the system. Unfortunately, this kind of failure
- persists. Repeated attempts over time by the client to access the
- service will fail. Only a change in the server or client software
- can fix this problem.
-
- System Failure: In these cases, the client or server misinterpreted a
- protocol operation, and this misinterpretation was serious enough
- to uncover a bug in the implementation. The bug causes a system
- crash or some kind of outage, either transient or permanent (until
- user reset). If this failure occurs in a server, not only will
- the connecting client lose service, but other clients attempting
- to connect will not get service. As an example, if a web server
- assumes that content passed to it from a client (created, for
- example, by a digital camera) is of a particular content type, and
- it always passes image content to a codec for decompression prior
- to storage, the codec might crash when it unexpectedly receives an
- image compressed in a different format. Of course, it might crash
- even if the Content-Type was correct, but the compressed bitstream
- was invalid. False assumptions merely introduce additional
- failure cases.
-
-
-
-
-
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-
- Poor User Experience: In these cases, the client and server
- communicate, but the user receives a diminished user experience.
- For example, if a client on a PC connects to a web site that
- provides content for mobile devices, the content may be
- underwhelming when viewed on the PC. Or, a client accessing a
- streaming media service may receive content of very low bitrate,
- even though the client supported better codecs. Indeed, if a user
- wishes to access content from both a cellular device and a PC
- using a shared address book (that is, an address book shared
- across multiple devices), the user would need two entries in that
- address book, and would need to use the right one from the right
- device. This is a poor user experience.
-
- Degraded Security: In these cases, a weaker security mechanism is
- used than the one that ought to have been used. As an example, a
- server in a domain might assume that it is only contacted by
- clients with a limited set of authentication algorithms, even
- though the clients have been recently upgraded to support a
- stronger set.
-
-6. Reasons Why the Assumptions Can Be False
-
- Assumptions made by clients and servers about the operation of
- protocols when contacting a particular domain are brittle, and can be
- wrong for many reasons. On the server side, many of the assumptions
- are based on the notion that a domain name will only be given to, or
- used by, a restricted set of clients. If the holder of the domain
- name assumes something about those clients, and can assume that only
- those clients use the domain name, then it can configure or program
- the server to operate specifically for those clients. Both parts of
- this assumption can be wrong, as discussed in more detail below.
-
- On the client side, the notion is similar, being based on the
- assumption that a server within a particular domain will provide a
- specific type of service. Sub-delegation and evolution, both
- discussed below, can make these assumptions wrong.
-
-6.1. Evolution
-
- The Internet and the devices that access it are constantly evolving,
- often at a rapid pace. Unfortunately, there is a tendency to build
- for the here and now, and then worry about the future at a later
- time. Many of the assumptions above are predicated on
- characteristics of today's clients and servers. Support for specific
- protocols, authentication techniques, or content are based on today's
- standards and today's devices. Even though they may, for the most
- part, be true, they won't always be. An excellent example is mobile
- devices. A server servicing a domain accessed by mobile devices
-
-
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-
- might try to make assumptions about the protocols, protocol
- extensions, security mechanisms, screen sizes, or processor power of
- such devices. However, all of these characteristics can and will
- change over time.
-
- When they do change, the change is usually evolutionary. The result
- is that the assumptions remain valid in some cases, but not in
- others. It is difficult to fix such systems, since it requires the
- server to detect what type of client is connecting, and what its
- capabilities are. Unless the system is built and deployed with these
- capability negotiation techniques built in to begin with, such
- detection can be extremely difficult. In fact, fixing it will often
- require the addition of such capability negotiation features that, if
- they had been in place and used to begin with, would have avoided the
- problem altogether.
-
-6.2. Leakage
-
- Servers also make assumptions because of the belief that they will
- only be accessed by specific clients, and in particular, those that
- are configured or provisioned to use the domain name. In essence,
- there is an assumption of community -- that a specific community
- knows and uses the domain name, while others outside of the community
- do not.
-
- The problem is that this notion of community is a false one. The
- Internet is global. The DNS is global. There is no technical
- barrier that separates those inside of the community from those
- outside. The ease with which information propagates across the
- Internet makes it extremely likely that such domain names will
- eventually find their way into clients outside of the presumed
- community. The ubiquitous presence of domain names in various URI
- formats, coupled with the ease of conveyance of URIs, makes such
- leakage merely a matter of time. Furthermore, since the DNS is
- global, and since it can only have one root [12], it becomes possible
- for clients outside of the community to search and find and use such
- "special" domain names.
-
- Indeed, this leakage is a strength of the Internet architecture, not
- a weakness. It enables global access to services from any client
- with a connection to the Internet. That, in turn, allows for rapid
- growth in the number of customers for any particular service.
-
-6.3. Sub-Delegation
-
- Clients and users make assumptions about domains because of the
- notion that there is some kind of centralized control that can
- enforce those assumptions. However, the DNS is not centralized; it
-
-
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-
- is distributed. If a domain doesn't delegate its sub-domains and has
- its records within a single zone, it is possible to maintain a
- centralized policy about operation of its domain. However, once a
- domain gets sufficiently large that the domain administrators begin
- to delegate sub-domains to other authorities, it becomes increasingly
- difficult to maintain any kind of central control on the nature of
- the service provided in each sub-domain.
-
- Similarly, the usage of domain names with human semantic connotation
- tends to lead to a registration of multiple domains in which a
- particular service is to run. As an example, a service provider with
- the name "example" might register and set up its services in
- "example.com", "example.net", and generally example.foo for each foo
- that is a valid TLD. This, like sub-delegation, results in a growth
- in the number of domains over which it is difficult to maintain
- centralized control.
-
- Not that it is not possible, since there are many examples of
- successful administration of policies across sub-domains many levels
- deep. However, it takes an increasing amount of effort to ensure
- this result, as it requires human intervention and the creation of
- process and procedure. Automated validation of adherence to policies
- is very difficult to do, as there is no way to automatically verify
- many policies that might be put into place.
-
- A less costly process for providing centralized management of
- policies is to just hope that any centralized policies are being
- followed, and then wait for complaints or perform random audits.
- Those approaches have many problems.
-
- The invalidation of assumptions due to sub-delegation is discussed in
- further detail in Section 4.1.3 of [8] and in Section 3.3 of [20].
-
- As a result of the fragility of policy continuity across sub-
- delegations, if a client or user assumes some kind of property
- associated with a TLD (such as ".wifi"), it becomes increasingly more
- likely with the number of sub-domains that this property will not
- exist in a server identified by a particular name. For example, in
- "store.chain.company.provider.wifi", there may be four levels of
- delegation from ".wifi", making it quite likely that, unless the
- holder of ".wifi" is working diligently, the properties that the
- holder of ".wifi" wishes to enforce are not present. These
- properties may not be present due to human error or due to a willful
- decision not to adhere to them.
-
-
-
-
-
-
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-
-6.4. Mobility
-
- One of the primary value propositions of a hostname as an identifier
- is its persistence. A client can change IP addresses, yet still
- retain a persistent identifier used by other hosts to reach it.
- Because their value derives from their persistence, hostnames tend to
- move with a host not just as it changes IP addresses, but as it
- changes access network providers and technologies. For this reason,
- assumptions made about a host based on the presumed access network
- corresponding to that hostname tend to be wrong over time. As an
- example, a PC might normally be connected to its broadband provider,
- and through dynamic DNS have a hostname within the domain of that
- provider. However, one cannot assume that any host within that
- network has access over a broadband link; the user could connect
- their PC over a low-bandwidth wireless access network and still
- retain its domain name.
-
-6.5. Human Error
-
- Of course, human error can be the source of errors in any system, and
- the same is true here. There are many examples relevant to the
- problem under discussion.
-
- A client implementation may make the assumption that, just because a
- DNS SRV record exists for a particular protocol in a particular
- domain, indicating that the service is available on some port, that
- the service is, in fact, running there. This assumption could be
- wrong because the SRV records haven't been updated by the system
- administrators to reflect the services currently running. As another
- example, a client might assume that a particular domain policy
- applies to all sub-domains. However, a system administrator might
- have omitted to apply the policy to servers running in one of those
- sub-domains.
-
-7. Recommendations
-
- Based on these problems, the clear conclusion is that clients,
- servers, and users should not make assumptions on the nature of the
- service provided to, or by, a domain. More specifically, however,
- the following can be said:
-
- Follow the specifications: When specifications define mandatory
- baseline procedures and formats, those should be implemented and
- supported, even if the expectation is that optional procedures
- will most often be used. For example, if a specification mandates
- a particular baseline authentication technique, but allows others
- to be negotiated and used, implementations need to implement the
- baseline authentication algorithm even if the other ones are used
-
-
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-
- most of the time. Put more simply, the behavior of the protocol
- machinery should never change based on the domain name of the
- host.
-
- Use capability negotiation: Many protocols are engineered with
- capability negotiation mechanisms. For example, a content
- negotiation framework has been defined for protocols using MIME
- content [13] [14] [15]. SIP allows for clients to negotiate the
- media types used in the multimedia session, as well as protocol
- parameters. HTTP allows for clients to negotiate the media types
- returned in requests for content. When such features are
- available in a protocol, client and servers should make use of
- them rather than making assumptions about supported capabilities.
- A corollary is that protocol designers should include such
- mechanisms when evolution is expected in the usage of the
- protocol.
-
- "Be liberal in what you accept, and conservative in what you send"
- [18]: This axiom of Internet protocol design is applicable here
- as well. Implementations should be prepared for the full breadth
- of what a protocol allows another entity to send, rather than be
- limiting in what it is willing to receive.
-
- To summarize -- there is never a need to make assumptions. Rather
- than doing so, utilize the specifications and the negotiation
- capabilities they provide, and the overall system will be robust and
- interoperable.
-
-8. A Note on RFC 2219 and RFC 2782
-
- Based on the definition of an assumption given here, the behavior
- hinted at by records in the DNS also represents an assumption. RFC
- 2219 [19] defines well-known aliases that can be used to construct
- domain names for reaching various well-known services in a domain.
- This approach was later followed by the definition of a new resource
- record, the SRV record [2], which specifies that a particular service
- is running on a server in a domain. Although both of these
- mechanisms are useful as a hint that a particular service is running
- in a domain, both of them represent assumptions that may be false.
- However, they differ in the set of reasons why those assumptions
- might be false.
-
- A client that assumes that "ftp.example.com" is an FTP server may be
- wrong because the presumed naming convention in RFC 2219 was not
- known by, or not followed by, the owner of domain.com. With RFC
- 2782, an SRV record for a particular service would be present only by
- explicit choice of the domain administrator, and thus a client that
-
-
-
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-
- assumes that the corresponding host provides this service would be
- wrong only because of human error in configuration. In this case,
- the assumption is less likely to be wrong, but it certainly can be.
-
- The only way to determine with certainty that a service is running on
- a host is to initiate a connection to the port for that service, and
- check. Implementations need to be careful not to codify any
- behaviors that cause failures should the information provided in the
- record actually be false. This borders on common sense for robust
- implementations, but it is valuable to raise this point explicitly.
-
-9. Security Considerations
-
- One of the assumptions that can be made by clients or servers is the
- availability and usage (or lack thereof) of certain security
- protocols and algorithms. For example, a client accessing a service
- in a particular domain might assume a specific authentication
- algorithm or hash function in the application protocol. It is
- possible that, over time, weaknesses are found in such a technique,
- requiring usage of a different mechanism. Similarly, a system might
- start with an insecure mechanism, and then decide later on to use a
- secure one. In either case, assumptions made on security properties
- can result in interoperability failures, or worse yet, providing
- service in an insecure way, even though the client asked for, and
- thought it would get, secure service. These kinds of assumptions are
- fundamentally unsound even if the records themselves are secured with
- DNSSEC.
-
-10. Acknowledgements
-
- The IAB would like to thank John Klensin, Keith Moore and Peter Koch
- for their comments.
-
-11. IAB Members
-
- Internet Architecture Board members at the time of writing of this
- document are:
-
- Bernard Aboba
-
- Loa Andersson
-
- Brian Carpenter
-
- Leslie Daigle
-
- Patrik Faltstrom
-
-
-
-
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-
- Bob Hinden
-
- Kurtis Lindqvist
-
- David Meyer
-
- Pekka Nikander
-
- Eric Rescorla
-
- Pete Resnick
-
- Jonathan Rosenberg
-
-12. Informative References
-
- [1] Mockapetris, P., "Domain names - concepts and facilities",
- STD 13, RFC 1034, November 1987.
-
- [2] Gulbrandsen, A., Vixie, P., and L. Esibov, "A DNS RR for
- specifying the location of services (DNS SRV)", RFC 2782,
- February 2000.
-
- [3] Mealling, M., "Dynamic Delegation Discovery System (DDDS) Part
- Three: The Domain Name System (DNS) Database", RFC 3403,
- October 2002.
-
- [4] Davis, C., Vixie, P., Goodwin, T., and I. Dickinson, "A Means
- for Expressing Location Information in the Domain Name System",
- RFC 1876, January 1996.
-
- [5] Fielding, R., Gettys, J., Mogul, J., Frystyk, H., Masinter, L.,
- Leach, P., and T. Berners-Lee, "Hypertext Transfer Protocol --
- HTTP/1.1", RFC 2616, June 1999.
-
- [6] Schulzrinne, H., Rao, A., and R. Lanphier, "Real Time Streaming
- Protocol (RTSP)", RFC 2326, April 1998.
-
- [7] Rosenberg, J., Schulzrinne, H., Camarillo, G., Johnston, A.,
- Peterson, J., Sparks, R., Handley, M., and E. Schooler, "SIP:
- Session Initiation Protocol", RFC 3261, June 2002.
-
- [8] Eastlake, D., ".sex Considered Dangerous", RFC 3675,
- February 2004.
-
- [9] Klensin, J., "Simple Mail Transfer Protocol", RFC 2821,
- April 2001.
-
-
-
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-
-
- [10] Niemi, A., Arkko, J., and V. Torvinen, "Hypertext Transfer
- Protocol (HTTP) Digest Authentication Using Authentication and
- Key Agreement (AKA)", RFC 3310, September 2002.
-
- [11] Freed, N. and N. Borenstein, "Multipurpose Internet Mail
- Extensions (MIME) Part One: Format of Internet Message Bodies",
- RFC 2045, November 1996.
-
- [12] Internet Architecture Board, "IAB Technical Comment on the
- Unique DNS Root", RFC 2826, May 2000.
-
- [13] Klyne, G., "Indicating Media Features for MIME Content",
- RFC 2912, September 2000.
-
- [14] Klyne, G., "A Syntax for Describing Media Feature Sets",
- RFC 2533, March 1999.
-
- [15] Klyne, G., "Protocol-independent Content Negotiation
- Framework", RFC 2703, September 1999.
-
- [16] Rescorla, E., "HTTP Over TLS", RFC 2818, May 2000.
-
- [17] Rosenberg, J. and H. Schulzrinne, "Reliability of Provisional
- Responses in Session Initiation Protocol (SIP)", RFC 3262,
- June 2002.
-
- [18] Braden, R., "Requirements for Internet Hosts - Communication
- Layers", STD 3, RFC 1122, October 1989.
-
- [19] Hamilton, M. and R. Wright, "Use of DNS Aliases for Network
- Services", BCP 17, RFC 2219, October 1997.
-
- [20] Faltstrom, P., "Design Choices When Expanding DNS", Work in
- Progress, June 2005.
-
-Author's Address
-
- Jonathan Rosenberg, Editor
- IAB
- 600 Lanidex Plaza
- Parsippany, NJ 07054
- US
-
- Phone: +1 973 952-5000
- EMail: jdrosen@cisco.com
- URI: http://www.jdrosen.net
-
-
-
-
-
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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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-
-
-
-
-
-
-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.
-
-
-
-
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-Josefsson Standards Track [Page 1]
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-
-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
-
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-Josefsson Standards Track [Page 2]
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-
-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
-
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- 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
-
-
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- 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.
-
-
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- 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:
-
-
-
-
-
-
-
-
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- 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.
-
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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
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- 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
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- 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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-
-Acknowledgement
-
- Funding for the RFC Editor function is provided by the IETF
- Administrative Support Activity (IASA).
-
-
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-
-
-
-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.
-
-
-
-
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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
-
-
-
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- 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
-
-
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-
-
- 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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-
-
- 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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-
-
- 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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-
-
-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.
-
-
-
-
-
-
-
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-
-
-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/
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
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-
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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. Andrews
-Request for Comments: 4431 Internet Systems Consortium
-Category: Informational S. Weiler
- SPARTA, Inc.
- February 2006
-
-
- The DNSSEC Lookaside Validation (DLV) DNS Resource Record
-
-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 defines a new DNS resource record, called the DNSSEC
- Lookaside Validation (DLV) RR, for publishing DNSSEC trust anchors
- outside of the DNS delegation chain.
-
-1. Introduction
-
- DNSSEC [1] [2] [3] authenticates DNS data by building public-key
- signature chains along the DNS delegation chain from a trust anchor,
- ideally a trust anchor for the DNS root.
-
- This document defines a new resource record for publishing such trust
- anchors outside of the DNS's normal delegation chain. Use of these
- records by DNSSEC validators is outside the scope of this document,
- but it is expected that these records will help resolvers validate
- DNSSEC-signed data from zones whose ancestors either aren't signed or
- refuse to publish delegation signer (DS) records for their children.
-
-2. DLV Resource Record
-
- The DLV resource record has exactly the same wire and presentation
- formats as the DS resource record, defined in RFC 4034, Section 5.
- It uses the same IANA-assigned values in the algorithm and digest
- type fields as the DS record. (Those IANA registries are known as
- the "DNS Security Algorithm Numbers" and "DS RR Type Algorithm
- Numbers" registries.)
-
-
-
-
-
-Andrews & Weiler Informational [Page 1]
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-RFC 4431 DLV Resource Record February 2006
-
-
- The DLV record is a normal DNS record type without any special
- processing requirements. In particular, the DLV record does not
- inherit any of the special processing or handling requirements of the
- DS record type (described in Section 3.1.4.1 of RFC 4035). Unlike
- the DS record, the DLV record may not appear on the parent's side of
- a zone cut. A DLV record may, however, appear at the apex of a zone.
-
-3. Security Considerations
-
- For authoritative servers and resolvers that do not attempt to use
- DLV RRs as part of DNSSEC validation, there are no particular
- security concerns -- DLV RRs are just like any other DNS data.
-
- Software using DLV RRs as part of DNSSEC validation will almost
- certainly want to impose constraints on their use, but those
- constraints are best left to be described by the documents that more
- fully describe the particulars of how the records are used. At a
- minimum, it would be unwise to use the records without some sort of
- cryptographic authentication. More likely than not, DNSSEC itself
- will be used to authenticate the DLV RRs. Depending on how a DLV RR
- is used, failure to properly authenticate it could lead to
- significant additional security problems including failure to detect
- spoofed DNS data.
-
- RFC 4034, Section 8, describes security considerations specific to
- the DS RR. Those considerations are equally applicable to DLV RRs.
- Of particular note, the key tag field is used to help select DNSKEY
- RRs efficiently, but it does not uniquely identify a single DNSKEY
- RR. It is possible for two distinct DNSKEY RRs to have the same
- owner name, the same algorithm type, and the same key tag. An
- implementation that uses only the key tag to select a DNSKEY RR might
- select the wrong public key in some circumstances.
-
- For further discussion of the security implications of DNSSEC, see
- RFC 4033, RFC 4034, and RFC 4035.
-
-4. IANA Considerations
-
- IANA has assigned DNS type code 32769 to the DLV resource record from
- the Specification Required portion of the DNS Resource Record Type
- registry, as defined in [4].
-
- The DLV resource record reuses the same algorithm and digest type
- registries already used for the DS resource record, currently known
- as the "DNS Security Algorithm Numbers" and "DS RR Type Algorithm
- Numbers" registries.
-
-
-
-
-
-Andrews & Weiler Informational [Page 2]
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-RFC 4431 DLV Resource Record February 2006
-
-
-5. 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] Eastlake, D., Brunner-Williams, E., and B. Manning, "Domain Name
- System (DNS) IANA Considerations", BCP 42, RFC 2929,
- September 2000.
-
-Authors' Addresses
-
- Mark Andrews
- Internet Systems Consortium
- 950 Charter St.
- Redwood City, CA 94063
- US
-
- EMail: Mark_Andrews@isc.org
-
-
- Samuel Weiler
- SPARTA, Inc.
- 7075 Samuel Morse Drive
- Columbia, Maryland 21046
- US
-
- EMail: weiler@tislabs.com
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-Andrews & Weiler Informational [Page 3]
-\f
-RFC 4431 DLV Resource Record February 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).
-
-
-
-
-
-
-
-Andrews & Weiler Informational [Page 4]
-\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]
-\f
-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]
-\f
-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
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-Weiler & Ihren Standards Track [Page 7]
-\f
-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
- 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).
-
-
-
-
-
-
-
-Weiler & Ihren Standards Track [Page 8]
-\f
+++ /dev/null
-
-
-
-
-
-
-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.
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-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
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-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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-
-
- 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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-
-
- 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.
-
-
-
-
-
-
-
-
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-
-
-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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-
-
-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
-
-
-
-
-
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-
-
- 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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-
-
- 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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-
-
- 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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-
-
- 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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-RFC 4634 SHAs and HMAC-SHAs July 2006
-
-
-/*
- * 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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-RFC 4634 SHAs and HMAC-SHAs July 2006
-
-
-/*
- * 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.
- */
-
-
-
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-
-
-#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;
-
-
-
-
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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;
-}
-
-/*
-
-
-
-Eastlake 3rd & Hansen Informational [Page 29]
-\f
-RFC 4634 SHAs and HMAC-SHAs July 2006
-
-
- * 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]);
- }
-
-
-
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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
- };
-
-
-
-Eastlake 3rd & Hansen Informational [Page 38]
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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[])
-{
-
-
-
-Eastlake 3rd & Hansen Informational [Page 39]
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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]
-
-
-
-Eastlake 3rd & Hansen Informational [Page 40]
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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]));
-
-
-
-
-Eastlake 3rd & Hansen Informational [Page 42]
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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)) )
-
-
-
-
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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.
- *
-
-
-
-Eastlake 3rd & Hansen Informational [Page 53]
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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.
-
-
-
-Eastlake 3rd & Hansen Informational [Page 54]
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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.
-
-
-
-Eastlake 3rd & Hansen Informational [Page 56]
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-RFC 4634 SHAs and HMAC-SHAs July 2006
-
-
- *
- * 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;
-
-
-
-
-Eastlake 3rd & Hansen Informational [Page 58]
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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 */
-
-
-
-
-Eastlake 3rd & Hansen Informational [Page 59]
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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,
-
-
-
-Eastlake 3rd & Hansen Informational [Page 60]
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-RFC 4634 SHAs and HMAC-SHAs July 2006
-
-
- 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];
-
-
-
-Eastlake 3rd & Hansen Informational [Page 61]
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-RFC 4634 SHAs and HMAC-SHAs July 2006
-
-
- 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]
-\f
-RFC 4634 SHAs and HMAC-SHAs July 2006
-
-
- 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])
-
-
-
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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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-
-
- *
- * 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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-
-
-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);
-
-
-
-Eastlake 3rd & Hansen Informational [Page 78]
-\f
-RFC 4634 SHAs and HMAC-SHAs July 2006
-
-
-/*
- * 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]
-\f
-RFC 4634 SHAs and HMAC-SHAs July 2006
-
-
- "\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]
-\f
-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" \
-
-
-
-Eastlake 3rd & Hansen Informational [Page 81]
-\f
-RFC 4634 SHAs and HMAC-SHAs July 2006
-
-
- "\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];
-
-
-
-Eastlake 3rd & Hansen Informational [Page 82]
-\f
-RFC 4634 SHAs and HMAC-SHAs July 2006
-
-
-} 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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-
-
- "\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 }
- },
-
-
-
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-
-
- { /* 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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-RFC 4634 SHAs and HMAC-SHAs July 2006
-
-
- { /* 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]
-\f
-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]
-\f
-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]
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-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]
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-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]
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-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.
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-Kolkman & Gieben Informational [Page 1]
-\f
-RFC 4641 DNSSEC Operational Practices September 2006
-
-
-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
-
-
-
-
-Kolkman & Gieben Informational [Page 2]
-\f
-RFC 4641 DNSSEC Operational Practices September 2006
-
-
-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.
-
-
-
-
-
-
-Kolkman & Gieben Informational [Page 3]
-\f
-RFC 4641 DNSSEC Operational Practices September 2006
-
-
-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.
-
-
-
-
-
-
-
-
-
-
-Kolkman & Gieben Informational [Page 4]
-\f
-RFC 4641 DNSSEC Operational Practices September 2006
-
-
-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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-Kolkman & Gieben Informational [Page 30]
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-RFC 4641 DNSSEC Operational Practices September 2006
-
-
- 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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-Kolkman & Gieben Informational [Page 31]
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-RFC 4641 DNSSEC Operational Practices September 2006
-
-
-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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-RFC 4641 DNSSEC Operational Practices September 2006
-
-
- 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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-RFC 4641 DNSSEC Operational Practices September 2006
-
-
-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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-Kolkman & Gieben Informational [Page 34]
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-RFC 4641 DNSSEC Operational Practices September 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).
-
-
-
-
-
-
-
-Kolkman & Gieben Informational [Page 35]
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projects / thirdparty / bind9.git / commitdiff
