Internet Engineering Task Force (IETF) S. Turner
Request for Comments: 6150 IECA
Obsoletes: 1320 L. Chen
Category: Informational NIST
ISSN: 2070-1721 March 2011
MD4 to Historic Status
This document retires RFC 1320, which documents the MD4 algorithm,
and discusses the reasons for doing so. This document moves RFC 1320
to Historic status.
Status of This Memo
This document is not an Internet Standards Track specification; it is
published for informational purposes.
This document is a product of the Internet Engineering Task Force
(IETF). It represents the consensus of the IETF community. It has
received public review and has been approved for publication by the
Internet Engineering Steering Group (IESG). Not all documents
approved by the IESG are a candidate for any level of Internet
Standard; see Section 2 of RFC 5741.
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Turner & Chen Informational [Page 1]RFC 6150 MD2 to Historic Status March 20111. Introduction
MD4 [MD4] is a message digest algorithm that takes as input a message
of arbitrary length and produces as output a 128-bit "fingerprint" or
"message digest" of the input. This document retires [MD4].
Specifically, this document moves RFC 1320 [MD4] to Historic status.
The reasons for taking this action are discussed.
[HASH-Attack] summarizes the use of hashes in many protocols and
discusses how attacks against a message digest algorithm's one-way
and collision-free properties affect and do not affect Internet
protocols. Familiarity with [HASH-Attack] is assumed.
MD4 was published in 1992 as an Informational RFC. Since its
publication, MD4 has been under attack [denBORBOS1992] [DOBB1995]
[DOBB1996] [GLRW2010] [WLDCY2005] [LUER2008]. In fact, RSA, in 1996,
suggested that MD4 should not be used [RSA-AdviceOnMD4]. Microsoft
also made similar statements [MS-AdviceOnMD4].
In Section 6, this document discusses attacks against MD4 that
indicate use of MD4 is no longer appropriate when collision
resistance is required. Section 6 also discusses attacks against
MD4's pre-image and second pre-image resistance. Additionally,
attacks against MD4 used in message authentication with a shared
secret (i.e., HMAC-MD4) are discussed.
3. Documents that Reference RFC 1320
Use of MD4 has been specified in the following RFCs:
Internet Standard (IS):
o [RFC2289] A One-Time Password System.
Draft Standard (DS):
o [RFC1629] Guidelines for OSI NSAP Allocation in the Internet.
Proposed Standard (PS):
o [RFC3961] Encryption and Checksum Specifications for Kerberos 5.
Best Current Practice (BCP):
o [RFC4086] Randomness Requirements for Security.
Turner & Chen Informational [Page 2]RFC 6150 MD2 to Historic Status March 2011
o [RFC1760] The S/KEY One-Time Password System.
o [RFC1983] Internet Users' Glossary.
o [RFC2433] Microsoft PPP CHAP Extensions.
o [RFC2759] Microsoft PPP CHAP Extensions, Version 2.
o [RFC3174] US Secure Hash Algorithm 1 (SHA1).
o [RFC4757] The RC4-HMAC Kerberos Encryption Types Used by
o [RFC5126] CMS Advanced Electronic Signatures (CAdES).
There are other RFCs that refer to MD2, but they have been either
moved to Historic status or obsoleted by a later RFC. References and
discussions about these RFCs are omitted. The notable exceptions