draft-ietf-dnsext-tsig-md5-deprecated-02.txt   draft-ietf-dnsext-tsig-md5-deprecated-03.txt 
DNSext Working Group F. Dupont DNSext Working Group F. Dupont
Internet-Draft ISC Internet-Draft ISC
Updates: 2845,2930,4635 April 27, 2009 Updates: 2845,2930,4635 May 8, 2009
(if approved) (if approved)
Intended status: Standards Track Intended status: Standards Track
Expires: October 29, 2009 Expires: November 9, 2009
Deprecation of HMAC-MD5 in DNS TSIG and TKEY Resource Records Deprecation of HMAC-MD5 in DNS TSIG and TKEY Resource Records
draft-ietf-dnsext-tsig-md5-deprecated-02.txt draft-ietf-dnsext-tsig-md5-deprecated-03.txt
Status of this Memo Status of this Memo
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Trust the right to allow modifications of such material outside the Trust the right to allow modifications of such material outside the
IETF Standards Process. Without obtaining an adequate license from IETF Standards Process. Without obtaining an adequate license from
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This Internet-Draft will expire on October 29, 2009. This Internet-Draft will expire on November 9, 2009.
Copyright Notice Copyright Notice
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Please review these documents carefully, as they describe your rights Please review these documents carefully, as they describe your rights
and restrictions with respect to this document. and restrictions with respect to this document.
Abstract Abstract
The main goal of this document is to deprecate the use of HMAC-MD5 as The main purpose of this document is to deprecate the use of HMAC-MD5
an algorithm for the TSIG (secret key transaction authentication) as an algorithm for the TSIG (secret key transaction authentication)
resource record in the DNS (domain name system). resource record in the DNS (domain name system), and the use of MD5
in TKEY (secret key establishment for DNS).
1. Introduction 1. Introduction
The secret key transaction authentication for DNS (TSIG, [RFC2845]) The secret key transaction authentication for DNS (TSIG, [RFC2845])
was defined with the HMAC-MD5 [RFC2104] cryptographic algorithm. As was defined with the HMAC-MD5 [RFC2104] cryptographic algorithm.
the MD5 [RFC1321] security was recognized to be lower than expected, When the MD5 [RFC1321] security came to be considered lower than
[RFC4635] standardized new TSIG algorithms based on SHA expected, [RFC4635] standardized new TSIG algorithms based on SHA
[RFC3174][RFC3874][RFC4634] digests. [RFC3174][RFC3874][RFC4634] digests.
But [RFC4635] did not deprecate the HMAC-MD5 algorithm. This But [RFC4635] did not deprecate the HMAC-MD5 algorithm. This
document is targeted to complete the process, in details: document is targeted to complete the process, in detail:
1. Mark HMAC-MD5.SIG-ALG.REG.INT as optional in the TSIG algorithm 1. Mark HMAC-MD5.SIG-ALG.REG.INT as optional in the TSIG algorithm
name registry managed by the IANA under the IETF Review Policy name registry managed by the IANA under the IETF Review Policy
[RFC5226] [RFC5226]
2. Make HMAC-MD5.SIG-ALG.REG.INT support "not Mandatory" for 2. Make HMAC-MD5.SIG-ALG.REG.INT support "not Mandatory" for
implementations implementations
3. Provide a keying material derivation for the secret key 3. Provide a keying material derivation for the secret key
establishment for DNS (TKEY, [RFC2930]) using a Diffie-Hellman establishment for DNS (TKEY, [RFC2930]) using a Diffie-Hellman
exchange with SHA256 [RFC4634] in place of MD5 [RFC1321] exchange with SHA256 [RFC4634] in place of MD5 [RFC1321]
4. Finally recommend the use of HMAC-SHA256. 4. Finally recommend the use of HMAC-SHA256.
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| hmac-sha224 | Optional | [RFC4635] | | hmac-sha224 | Optional | [RFC4635] |
| hmac-sha256 | Mandatory | [RFC4635] | | hmac-sha256 | Mandatory | [RFC4635] |
| hmac-sha384 | Optional | [RFC4635] | | hmac-sha384 | Optional | [RFC4635] |
| hmac-sha512 | Optional | [RFC4635] | | hmac-sha512 | Optional | [RFC4635] |
+--------------------------+------------------------+-------------+ +--------------------------+------------------------+-------------+
where [] is this document. where [] is this document.
5. Availability Considerations 5. Availability Considerations
MD5 is no more universally available and its use should lead to MD5 is no longer universally available and its use may lead to
increasing operation issues. SHA1 is likely to suffer from the same increasing operation issues. SHA1 is likely to suffer from the same
kind of problem. To summary MD5 has reached end-of-life and SHA1 kind of problem. In summary MD5 has reached end-of-life and SHA1
follows few years behind. will likely follow in the near term.
According to [RFC4635], implementations which support TSIG are According to [RFC4635], implementations which support TSIG are
REQUIRED to implement HMAC-SHA256. REQUIRED to implement HMAC-SHA256.
6. Security Considerations 6. Security Considerations
This document does not assume anything about the cryptographic This document does not assume anything about the cryptographic
security of different hash algorithms. It is a routine maintenance, security of different hash algorithms. Its purpose is a better
its goal is better availability of some security mechanisms in a availability of some security mechanisms in a predictable time frame.
predictable future.
Requirement levels are adjusted for TSIG and related specifications Requirement levels are adjusted for TSIG and related specifications
(i.e., TKEY): (i.e., TKEY):
The support of HMAC-MD5 is changed from mandatory to optional.
The use of MD5 and HMAC-MD5 is NOT RECOMMENDED. The use of MD5 and HMAC-MD5 is NOT RECOMMENDED.
The use of HMAC-SHA256 is RECOMMENDED. The use of HMAC-SHA256 is RECOMMENDED.
7. Acknowledgments 7. Acknowledgments
Olafur Gudmundsson kindly helped in the procedure to deprecate the Olafur Gudmundsson kindly helped in the procedure to deprecate the
MD5 use in TSIG, i.e., the procedure which led to this memo. Alfred MD5 use in TSIG, i.e., the procedure which led to this memo. Alfred
Hoenes, Peter Koch and Paul Hoffman proposed some improvements. Hoenes, Peter Koch, Paul Hoffman and Edward Lewis proposed some
improvements.
8. References 8. References
8.1. Normative References 8.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", RFC 2119, BCP 14, March 1997. Requirement Levels", RFC 2119, BCP 14, March 1997.
[RFC2845] Vixie, P., Gudmundsson, O., Eastlake, D., and B. [RFC2845] Vixie, P., Gudmundsson, O., Eastlake, D., and B.
Wellington, "Secret Key Transaction Authentication for DNS Wellington, "Secret Key Transaction Authentication for DNS
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