Standards Maturity Variance Regarding the TCP MD5 Signature Option (RFC 2385) and the BGP-4 Specification
RFC 4278

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Network Working Group                                        S. Bellovin
Request for Comments: 4278                            AT&T Labs Research
Category: Informational                                         A. Zinin
                                                                 Alcatel
                                                            January 2006

  Standards Maturity Variance Regarding the TCP MD5 Signature Option
                 (RFC 2385) and the BGP-4 Specification

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 IETF Standards Process requires that all normative references for
   a document be at the same or higher level of standardization.  RFC
   2026 section 9.1 allows the IESG to grant a variance to the standard
   practices of the IETF.  This document explains why the IESG is
   considering doing so for the revised version of the BGP-4
   specification, which refers normatively to RFC 2385, "Protection of
   BGP Sessions via the TCP MD5 Signature Option".  RFC 2385 will remain
   at the Proposed Standard level.

1.  Introduction

   The IETF Standards Process [RFC2026] requires that all normative
   references for a document be at the same or higher level of
   standardization.  RFC 2026 section 9.1 allows the IESG to grant a
   variance to the standard practices of the IETF.  Pursuant to that, it
   is considering publishing the updated BGP-4 specification [RFC4271]
   as Draft Standard, despite the normative reference to [RFC2385],
   "Protection of BGP Sessions via the TCP MD5 Signature Option".  RFC
   2385 will remain a Proposed Standard.  (Note that although the title
   of [RFC2385] includes the word "signature", the technology described
   in it is commonly known as a Message Authentication Code or MAC, and
   should not be confused with digital signature technologies.)

   [RFC2385], which is widely implemented, is the only transmission
   security mechanism defined for BGP-4.  Other possible mechanisms,
   such as IPsec [RFC2401] and TLS [RFC2246], are rarely, if ever, used

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RFC 4278    Standards Maturity Variance: RFC 2385 and BGP-4 January 2006

   for this purpose.  Given the long-standing requirement for security
   features in protocols, it is not possible to advance BGP-4 without a
   mandated security mechanism.

   The conflict of maturity levels between specifications would normally
   be resolved by advancing the specification being referred to along
   the standards track, to the level of maturity that the referring
   specification needs to achieve.  However, in the particular case
   considered here, the IESG believes that [RFC2385], though adequate
   for BGP deployments at this moment, is not strong enough for general
   use, and thus should not be progressed along the standards track.  In
   this situation, the IESG believes that variance procedure should be
   used to allow the updated BGP-4 specification to be published as
   Draft Standard.

   The following sections of the document give detailed explanations of
   the statements above.

2.  Draft Standard Requirements

   The requirements for Proposed Standards and Draft Standards are given
   in [RFC2026].  For Proposed Standards, [RFC2026] warns that:

        Implementors should treat Proposed Standards as immature
        specifications.  It is desirable to implement them in order to
        gain experience and to validate, test, and clarify the
        specification.  However, since the content of Proposed Standards
        may be changed if problems are found or better solutions are
        identified, deploying implementations of such standards into a
        disruption-sensitive environment is not recommended.

   In other words, it is considered reasonable for flaws to be
   discovered in Proposed Standards.

   The requirements for Draft Standards are higher:

        A Draft Standard must be well-understood and known to be quite
        stable, both in its semantics and as a basis for developing an
        implementation.

   In other words, any document that has known deficiencies should not
   be promoted to Draft Standard.

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RFC 4278    Standards Maturity Variance: RFC 2385 and BGP-4 January 2006

3.  The TCP MD5 Signature Option

   [RFC2385], despite its 1998 publication date, describes a Message
   Authentication Code (MAC) that is considerably older.  It utilizes a
   technique known as a "keyed hash function", using MD5 [RFC1321] as
   the hash function.  When the original code was developed, this was
   believed to be a reasonable technique, especially if the key was
   appended (rather than prepended) to the data being protected.  But