draft-ietf-dnsext-tsig-sha-00.txt   draft-ietf-dnsext-tsig-sha-01.txt 
INTERNET-DRAFT Donald E. Eastlake 3rd INTERNET-DRAFT Donald E. Eastlake 3rd
UPDATES RFC 2845 Motorola Laboratories UPDATES RFC 2845 Motorola Laboratories
Expires: February 2005 August 2004 Expires: August 2005 February 2005
HMAC SHA TSIG Algorithm Identifiers HMAC SHA TSIG Algorithm Identifiers
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<draft-ietf-dnsext-tsig-sha-00.txt> <draft-ietf-dnsext-tsig-sha-01.txt>
Status of This Document Status of This Document
By submitting this Internet-Draft, I certify that any applicable By submitting this Internet-Draft, I certify that any applicable
patent or other IPR claims of which I am aware have been disclosed, 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 or will be disclosed, and any of which I become aware will be
disclosed, in accordance with RFC 3668. disclosed, in accordance with RFC 3668.
This draft is intended to be become a Proposed Standard RFC. This draft is intended to be become a Proposed Standard RFC.
Distribution of this document is unlimited. Comments should be sent Distribution of this document is unlimited. Comments should be sent
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http://www.ietf.org/1id-abstracts.html http://www.ietf.org/1id-abstracts.html
The list of Internet-Draft Shadow Directories can be accessed at The list of Internet-Draft Shadow Directories can be accessed at
http://www.ietf.org/shadow.html http://www.ietf.org/shadow.html
Abstract Abstract
Use of the TSIG DNS resource record requires specification of a Use of the TSIG DNS resource record requires specification of a
cryptographic message authentication code. Currently identifiers cryptographic message authentication code. Currently identifiers
have been specified only for the HMAC-MD5 and GSS TSIG algorithms. have been specified only for the HMAC-MD5 and GSS TSIG algorithms.
This document standardizes identifiers for additional HMAC SHA TSIG This document standardizes identifiers and implementation
algorithms and standardizes how to specify the truncation of HMAC requirements for additional HMAC SHA TSIG algorithms and standardizes
values. how to specify the truncation of HMAC values.
Copyright Notice Copyright Notice
Copyright (C) The Internet Society 2004. All Rights Reserved. Copyright (C) The Internet Society 2005. All Rights Reserved.
INTERNET-DRAFT HMAC-SHA TSIG Identifiers INTERNET-DRAFT HMAC-SHA TSIG Identifiers
Table of Contents Table of Contents
Status of This Document....................................1 Status of This Document....................................1
Abstract...................................................1 Abstract...................................................1
Copyright Notice...........................................1 Copyright Notice...........................................1
Table of Contents..........................................2 Table of Contents..........................................2
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3. Specifying Truncation...................................5 3. Specifying Truncation...................................5
4. IANA Considerations.....................................6 4. IANA Considerations.....................................6
5. Security Considerations.................................6 5. Security Considerations.................................6
6. Copyright and Disclaimer................................6 6. Copyright and Disclaimer................................6
7. Normative References....................................7 7. Normative References....................................7
8. Informative References..................................7 8. Informative References..................................7
Authors Address............................................8 Author's Address...........................................8
Expiration and File Name...................................8 Expiration and File Name...................................8
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1. Introduction 1. Introduction
[RFC 2845] specifies a TSIG Resource Record (RR) that can be used to [RFC 2845] specifies a TSIG Resource Record (RR) that can be used to
authenticate DNS queries and responses. This RR contains a domain authenticate DNS queries and responses. This RR contains a domain
name syntax data item which names the authentication algorithm used. name syntax data item which names the authentication algorithm used.
[RFC 2845] defines the HMAC-MD5.SIG-ALG.REG.INT name for [RFC 2845] defines the HMAC-MD5.SIG-ALG.REG.INT name for
authentication codes using the HMAC [RFC 2104] algorithm with the MD5 authentication codes using the HMAC [RFC 2104] algorithm with the MD5
[RFC 1321] hash algorithm. IANA has also registered "gss-tsig" as an [RFC 1321] hash algorithm. IANA has also registered "gss-tsig" as an
identifier for TSIG authentication where the cryptographic operations identifier for TSIG authentication where the cryptographic operations
are delegated to GSS [RFC 3645]. are delegated to GSS [RFC 3645].
In section 2, this document specifies additional names for TSIG In section 2, this document specifies additional names for TSIG
authentication algorithms based on US NIST SHA algorithms and HMAC. authentication algorithms based on US NIST SHA algorithms and HMAC
and specifies the implementation requirements for those algorithms.
In section 3, this document specifies the meaning of inequality In section 3, this document specifies the meaning of inequality
between the normal output size of the specified hash function and the between the normal output size of the specified hash function and the
length of MAC (message authentication code) data given in the TSIG length of MAC (message authentication code) data given in the TSIG
RR. In particular, it specifies that a shorter length field value RR. In particular, it specifies that a shorter length field value
specifies truncation and a longer length field is an error. specifies truncation and a longer length field is an error.
INTERNET-DRAFT HMAC-SHA TSIG Identifiers INTERNET-DRAFT HMAC-SHA TSIG Identifiers
2. Algorithms and Identifiers 2. Algorithms and Identifiers
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queries and responses. They are intended to be efficient symmetric queries and responses. They are intended to be efficient symmetric
authentication codes based on a shared secret. (Asymmetric signatures authentication codes based on a shared secret. (Asymmetric signatures
can be provided using the SIG RR [RFC 2931]. In particular, SIG(0) can be provided using the SIG RR [RFC 2931]. In particular, SIG(0)
can be used for transaction signatures.) Used with a strong hash can be used for transaction signatures.) Used with a strong hash
function, HMAC [RFC 2104] provides a way to calculate such symmetric function, HMAC [RFC 2104] provides a way to calculate such symmetric
authentication codes. The only specified HMAC based TSIG algorithm authentication codes. The only specified HMAC based TSIG algorithm
identifier has been HMAC-MD5.SIG-ALG.REG.INT based on MD5 [RFC 1321]. 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 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 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 the SHA family [FIPS 180-2, RFC 3874] with 224, 256, 384, and 512
bits, may be preferred in some case. Use of TSIG between a DNS bits, may be preferred in some case particularly since increasingly
resolver and server is by mutual agreement. That agreement can successful cryptanalytic attacks are being made on the shorter
include the support of additional algorithms. hashes. Use of TSIG between a DNS resolver and server is by mutual
agreement. That agreement can include the support of additional
algorithms and may specify policies as to which algorithms are
acceptable.
For completeness in relation to HMAC based algorithms, the current The current HMAC-MD5.SIG-ALG.REG.INT identifier is included in the
HMAC-MD5.SIG-ALG.REG.INT identifier is included in the table below. table below for convenience. Implementations which support TSIG MUST
Implementations which support TSIG MUST implement HMAC MD5, SHOULD also implement HMAC SHA1 and HMAC SHA256 and MAY implement gss-tsig
implement HMAC SHA-1, and MAY implement gss-tsig and the other and the other algorithms listed below.
algorithms listed below.
Mandatory HMAC-MD5.SIG-ALG.REG.INT Mandatory HMAC-MD5.SIG-ALG.REG.INT
Recommended hmac-sha1 Mandatory hmac-sha1
Optional hmac-sha224 Optional hmac-sha224
Optional hmac-sha256 Mandatory hmac-sha256
Optional hamc-sha384 Optional hamc-sha384
Optional hmac-sha512 Optional hmac-sha512
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3. Specifying Truncation 3. Specifying Truncation
In some cases, it is reasonable to truncate the output of HMAC and In some cases, it is reasonable to truncate the output of HMAC and
use the truncated value for authentication. HMAC SHA-1 truncated to use the truncated value for authentication. HMAC SHA-1 truncated to
96 bits is an optional available in several IETF protocols including 96 bits is an optional available in several IETF protocols including
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IANA. IANA.
5. Security Considerations 5. Security Considerations
For all of the message authentication code algorithms listed herein, For all of the message authentication code algorithms listed herein,
those producing longer values are believed to be stronger; however, those producing longer values are believed to be stronger; however,
while there are some arguments that mild truncation can strengthen a while there are some arguments that mild truncation can strengthen a
MAC by reducing the information available to an attacker, excessive MAC by reducing the information available to an attacker, excessive
truncation clearly weakens authentication by reducing the number of truncation clearly weakens authentication by reducing the number of
bits an attacker has to try to force. See [RFC 2104] which recommends 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 that an HMAC never be truncated to less than half its length nor to
less than 80 bits (10 octets). less than 80 bits (10 octets).
Significant progress has been made recently in cryptanalysis of hash
function of the type used herein. While the results so far should not
effect HMAC, the stronger SHA-1 and SHA-256 algorithms are being made
mandatory due to caution.
See also the Security Considerations section of [RFC 2845]. See also the Security Considerations section of [RFC 2845].
6. Copyright and Disclaimer 6. Copyright and Disclaimer
Copyright (C) The Internet Society 2004. This document is subject to Copyright (C) The Internet Society 2005. This document is subject to
the rights, licenses and restrictions contained in BCP 78 and except the rights, licenses and restrictions contained in BCP 78 and except
as set forth therein, the authors retain all their rights. as set forth therein, the authors retain all their rights.
This document and the information contained herein are provided on an This document and the information contained herein are provided on an
"AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS
OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND THE INTERNET OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND THE INTERNET
ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED, ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED,
INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE
INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED
WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
INTERNET-DRAFT HMAC-SHA TSIG Identifiers INTERNET-DRAFT HMAC-SHA TSIG Identifiers
7. Normative References 7. Normative References
[FIPS 180-2] - "Secure Hash Standard", (SHA-1/256/384/512) US Federal [FIPS 180-2] - "Secure Hash Standard", (SHA-1/224/256/384/512) US
Information Processing Standard, Draft, 1 August 2002. Federal Information Processing Standard, with Change Notice 1,
February 2004.
[RFC 1321] - Rivest, R., "The MD5 Message-Digest Algorithm ", RFC [RFC 1321] - Rivest, R., "The MD5 Message-Digest Algorithm ", RFC
1321, April 1992. 1321, April 1992.
[RFC 2104] - Krawczyk, H., Bellare, M., and R. Canetti, "HMAC: Keyed- [RFC 2104] - Krawczyk, H., Bellare, M., and R. Canetti, "HMAC: Keyed-
Hashing for Message Authentication", RFC 2104, February 1997. Hashing for Message Authentication", RFC 2104, February 1997.
[RFC 2434] - Narten, T. and H. Alvestrand, "Guidelines for Writing an [RFC 2434] - Narten, T. and H. Alvestrand, "Guidelines for Writing an
IANA Considerations Section in RFCs", BCP 26, RFC 2434, October 1998. IANA Considerations Section in RFCs", BCP 26, RFC 2434, October 1998.
[RFC 2845] - Vixie, P., Gudmundsson, O., Eastlake 3rd, D., and B. [RFC 2845] - Vixie, P., Gudmundsson, O., Eastlake 3rd, D., and B.
Wellington, "Secret Key Transaction Authentication for DNS (TSIG)", Wellington, "Secret Key Transaction Authentication for DNS (TSIG)",
RFC 2845, May 2000. 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. 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 [RFC 2931] - Eastlake 3rd, D., "DNS Request and Transaction
Signatures ( SIG(0)s )", RFC 2931, September 2000. Signatures ( SIG(0)s )", RFC 2931, September 2000.
[RFC 3174] - Eastlake 3rd, D. and P. Jones, "US Secure Hash Algorithm [RFC 3174] - Eastlake 3rd, D. and P. Jones, "US Secure Hash Algorithm
1 (SHA1)", RFC 3174, September 2001. 1 (SHA1)", RFC 3174, September 2001.
[RFC 3645] - Kwan, S., Garg, P., Gilroy, J., Esibov, L., Westhead, [RFC 3645] - Kwan, S., Garg, P., Gilroy, J., Esibov, L., Westhead,
J., and R. Hall, "Generic Security Service Algorithm for Secret Key J., and R. Hall, "Generic Security Service Algorithm for Secret Key
Transaction Authentication for DNS (GSS-TSIG)", RFC 3645, October Transaction Authentication for DNS (GSS-TSIG)", RFC 3645, October
2003. 2003.
[RFC 3874] - "A 224-bit One-way Hash Function: SHA-224", R. Housley,
September 2004,
INTERNET-DRAFT HMAC-SHA TSIG Identifiers INTERNET-DRAFT HMAC-SHA TSIG Identifiers
Authors Address Author's Address
Donald E. Eastlake 3rd Donald E. Eastlake 3rd
Motorola Laboratories Motorola Laboratories
155 Beaver Street 155 Beaver Street
Milford, MA 01757 USA Milford, MA 01757 USA
Telephone: +1-508-786-7554 (w) Telephone: +1-508-786-7554 (w)
+1-508-634-2066 (h) +1-508-634-2066 (h)
EMail: Donald.Eastlake@motorola.com EMail: Donald.Eastlake@motorola.com
Expiration and File Name Expiration and File Name
This draft expires in February 2005. This draft expires in August 2005.
Its file name is draft-ietf-dnsext-tsig-sha-00.txt Its file name is draft-ietf-dnsext-tsig-sha-01.txt
 End of changes. 

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