--- /dev/null
+
+
+INTERNET-DRAFT Donald E. Eastlake 3rd
+UPDATES RFC 2845 Motorola Laboratories
+Expires: February 2005 August 2004
+
+
+ HMAC SHA TSIG Algorithm Identifiers
+ ---- --- ---- --------- -----------
+ <draft-ietf-dnsext-tsig-sha-00.txt>
+
+
+Status of This Document
+
+ By submitting this Internet-Draft, I certify that any applicable
+ patent or other IPR claims of which I am aware have been disclosed,
+ or will be disclosed, and any of which I become aware will be
+ disclosed, in accordance with RFC 3668.
+
+ This draft is intended to be become a Proposed Standard RFC.
+ Distribution of this document is unlimited. Comments should be sent
+ to the DNSEXT working group mailing list <namedroppers@ops.ietf.org>.
+
+ Internet-Drafts are working documents of the Internet Engineering
+ Task Force (IETF), its areas, and its working groups. Note that
+ other groups may also distribute working documents as Internet-
+ Drafts.
+
+ Internet-Drafts are draft documents valid for a maximum of six months
+ and may be updated, replaced, or obsoleted by other documents at any
+ time. It is inappropriate to use Internet-Drafts as reference
+ material or to cite them other than a "work in progress."
+
+ The list of current Internet-Drafts can be accessed at
+ http://www.ietf.org/1id-abstracts.html
+
+ The list of Internet-Draft Shadow Directories can be accessed at
+ http://www.ietf.org/shadow.html
+
+
+Abstract
+
+ Use of the TSIG DNS resource record requires specification of a
+ cryptographic message authentication code. Currently identifiers
+ have been specified only for the HMAC-MD5 and GSS TSIG algorithms.
+ This document standardizes identifiers for additional HMAC SHA TSIG
+ algorithms and standardizes how to specify the truncation of HMAC
+ values.
+
+
+Copyright Notice
+
+ Copyright (C) The Internet Society 2004. All Rights Reserved.
+
+
+
+
+D. Eastlake 3rd [Page 1]
+\f
+
+INTERNET-DRAFT HMAC-SHA TSIG Identifiers
+
+
+Table of Contents
+
+ Status of This Document....................................1
+ Abstract...................................................1
+ Copyright Notice...........................................1
+
+ Table of Contents..........................................2
+
+ 1. Introduction............................................3
+
+ 2. Algorithms and Identifiers..............................4
+
+ 3. Specifying Truncation...................................5
+
+ 4. IANA Considerations.....................................6
+ 5. Security Considerations.................................6
+ 6. Copyright and Disclaimer................................6
+
+ 7. Normative References....................................7
+ 8. Informative References..................................7
+
+ Authors Address............................................8
+ Expiration and File Name...................................8
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+D. Eastlake 3rd [Page 2]
+\f
+
+INTERNET-DRAFT HMAC-SHA TSIG Identifiers
+
+
+1. Introduction
+
+ [RFC 2845] specifies a TSIG Resource Record (RR) that can be used to
+ authenticate DNS queries and responses. This RR contains a domain
+ name syntax data item which names the authentication algorithm used.
+ [RFC 2845] defines the HMAC-MD5.SIG-ALG.REG.INT name for
+ authentication codes using the HMAC [RFC 2104] algorithm with the MD5
+ [RFC 1321] hash algorithm. IANA has also registered "gss-tsig" as an
+ identifier for TSIG authentication where the cryptographic operations
+ are delegated to GSS [RFC 3645].
+
+ In section 2, this document specifies additional names for TSIG
+ authentication algorithms based on US NIST SHA algorithms and HMAC.
+
+ In section 3, this document specifies the meaning of inequality
+ between the normal output size of the specified hash function and the
+ length of MAC (message authentication code) data given in the TSIG
+ RR. In particular, it specifies that a shorter length field value
+ specifies truncation and a longer length field is an error.
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+D. Eastlake 3rd [Page 3]
+\f
+
+INTERNET-DRAFT HMAC-SHA TSIG Identifiers
+
+
+2. Algorithms and Identifiers
+
+ TSIG Resource Records (RRs) [RFC 2845] are used to authenticate DNS
+ queries and responses. They are intended to be efficient symmetric
+ authentication codes based on a shared secret. (Asymmetric signatures
+ can be provided using the SIG RR [RFC 2931]. In particular, SIG(0)
+ can be used for transaction signatures.) Used with a strong hash
+ function, HMAC [RFC 2104] provides a way to calculate such symmetric
+ authentication codes. The only specified HMAC based TSIG algorithm
+ identifier has been HMAC-MD5.SIG-ALG.REG.INT based on MD5 [RFC 1321].
+
+ The use of SHA-1 [FIPS 180-1, RFC 3174], which is a 160 bit hash, as
+ compared with the 128 bits for MD5, and additional hash algorithms in
+ the SHA family [FIPS 180-2, RFC sha224] with 224, 256, 384, and 512
+ bits, may be preferred in some case. Use of TSIG between a DNS
+ resolver and server is by mutual agreement. That agreement can
+ include the support of additional algorithms.
+
+ For completeness in relation to HMAC based algorithms, the current
+ HMAC-MD5.SIG-ALG.REG.INT identifier is included in the table below.
+ Implementations which support TSIG MUST implement HMAC MD5, SHOULD
+ implement HMAC SHA-1, and MAY implement gss-tsig and the other
+ algorithms listed below.
+
+ Mandatory HMAC-MD5.SIG-ALG.REG.INT
+ Recommended hmac-sha1
+ Optional hmac-sha224
+ Optional hmac-sha256
+ Optional hamc-sha384
+ Optional hmac-sha512
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+D. Eastlake 3rd [Page 4]
+\f
+
+INTERNET-DRAFT HMAC-SHA TSIG Identifiers
+
+
+3. Specifying Truncation
+
+ In some cases, it is reasonable to truncate the output of HMAC and
+ use the truncated value for authentication. HMAC SHA-1 truncated to
+ 96 bits is an optional available in several IETF protocols including
+ IPSEC and TLS.
+
+ The TSIG RR [RFC 2845] includes a "MAC size" field, which gives the
+ size of the MAC field in octets. But [RFC 2845] does not specify what
+ to do if this MAC size differs from the length of the output of HMAC
+ for a particular hash function.
+
+ The specification for TSIG handling is changed as follows:
+
+ 1. If The "MAC size" field is larger than the HMAC output length or
+ is zero: This case MUST NOT be generated and if received MUST
+ cause the packet to be dropped and RCODE 1 (FORMERR) to be
+ returned.
+
+ 2. If the "MAC size" field equals the HMAC output length: Operation
+ is as described in [RFC 2845].
+
+ 3. If the "MAC size" field is less than the HMAC output length but is
+ not zero: This is sent when the signer has truncated the HMAC
+ output as described in RFC 2104, taking initial octets and
+ discarding trailing octets. TSIG truncation can only be to an
+ integral number of octets. On receipt of a packet with truncation
+ thus indicated, the locally calculated MAC is similarly truncated
+ and only the truncated values compared for authentication.
+
+ TSIG implementations SHOULD implement SHA-1 truncated to 96 bits (12
+ octets) and MAY implement any or all other truncations valid under
+ case 3 above.
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+D. Eastlake 3rd [Page 5]
+\f
+
+INTERNET-DRAFT HMAC-SHA TSIG Identifiers
+
+
+4. IANA Considerations
+
+ This document, on approval for publication as a standards track RFC,
+ registers the new TSIG algorithm identifiers listed in Section 2 with
+ IANA.
+
+
+
+5. Security Considerations
+
+ For all of the message authentication code algorithms listed herein,
+ those producing longer values are believed to be stronger; however,
+ while there are some arguments that mild truncation can strengthen a
+ MAC by reducing the information available to an attacker, excessive
+ truncation clearly weakens authentication by reducing the number of
+ bits an attacker has to try to force. See [RFC 2104] which recommends
+ that ah HMAC never be truncated to less than half its length nor to
+ less than 80 bits (10 octets).
+
+ See also the Security Considerations section of [RFC 2845].
+
+
+
+6. Copyright and Disclaimer
+
+ Copyright (C) The Internet Society 2004. 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.
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+D. Eastlake 3rd [Page 6]
+\f
+
+INTERNET-DRAFT HMAC-SHA TSIG Identifiers
+
+
+7. Normative References
+
+ [FIPS 180-2] - "Secure Hash Standard", (SHA-1/256/384/512) US Federal
+ Information Processing Standard, Draft, 1 August 2002.
+
+ [RFC 1321] - Rivest, R., "The MD5 Message-Digest Algorithm ", RFC
+ 1321, April 1992.
+
+ [RFC 2104] - Krawczyk, H., Bellare, M., and R. Canetti, "HMAC: Keyed-
+ Hashing for Message Authentication", RFC 2104, February 1997.
+
+ [RFC 2434] - Narten, T. and H. Alvestrand, "Guidelines for Writing an
+ IANA Considerations Section in RFCs", BCP 26, RFC 2434, October 1998.
+
+ [RFC 2845] - Vixie, P., Gudmundsson, O., Eastlake 3rd, D., and B.
+ Wellington, "Secret Key Transaction Authentication for DNS (TSIG)",
+ RFC 2845, May 2000.
+
+ [RFC sha224] - "A 224-bit One-way Hash Function: SHA-224", R.
+ Housley, December 2003, work in progress, draft-ietf-pkix-
+ sha224-*.txt.
+
+
+
+8. Informative References.
+
+ [FIPS 180-1] - Secure Hash Standard, (SHA-1) US Federal Information
+ Processing Standard, 17 April 1995.
+
+ [RFC 2931] - Eastlake 3rd, D., "DNS Request and Transaction
+ Signatures ( SIG(0)s )", RFC 2931, September 2000.
+
+ [RFC 3174] - Eastlake 3rd, D. and P. Jones, "US Secure Hash Algorithm
+ 1 (SHA1)", RFC 3174, September 2001.
+
+ [RFC 3645] - Kwan, S., Garg, P., Gilroy, J., Esibov, L., Westhead,
+ J., and R. Hall, "Generic Security Service Algorithm for Secret Key
+ Transaction Authentication for DNS (GSS-TSIG)", RFC 3645, October
+ 2003.
+
+
+
+
+
+
+
+
+
+
+
+
+
+D. Eastlake 3rd [Page 7]
+\f
+
+INTERNET-DRAFT HMAC-SHA TSIG Identifiers
+
+
+Authors Address
+
+ Donald E. Eastlake 3rd
+ Motorola Laboratories
+ 155 Beaver Street
+ Milford, MA 01757 USA
+
+ Telephone: +1-508-786-7554 (w)
+ +1-508-634-2066 (h)
+ EMail: Donald.Eastlake@motorola.com
+
+
+
+Expiration and File Name
+
+ This draft expires in February 2005.
+
+ Its file name is draft-ietf-dnsext-tsig-sha-00.txt
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+D. Eastlake 3rd [Page 8]
+\f
+
projects / thirdparty / bind9.git / commitdiff
