Deprecating MD5 and SHA-1 signature hashes in TLS 1.2
draft-ietf-tls-md5-sha1-deprecate-04

Document Type Active Internet-Draft (tls WG)
Authors Loganaden Velvindron  , Kathleen Moriarty  , Alessandro Ghedini 
Last updated 2020-12-12 (latest revision 2020-10-09)
Replaces draft-lvelvindron-tls-md5-sha1-deprecate
Stream Internent Engineering Task Force (IETF)
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Stream WG state Submitted to IESG for Publication (wg milestone: Jul 2020 - Submit "Deprecating ... )
Document shepherd Joseph Salowey
Shepherd write-up Show (last changed 2021-01-21)
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Send notices to joe@salowey.net, loganaden@gmail.com
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Internet Engineering Task Force                            L. Velvindron
Internet-Draft                                             cyberstorm.mu
Updates: 5246 7525 (if approved)                             K. Moriarty
Intended status: Standards Track                       Dell Technologies
Expires: April 12, 2021                                       A. Ghedini
                                                         Cloudflare Inc.
                                                         October 9, 2020

         Deprecating MD5 and SHA-1 signature hashes in TLS 1.2
                  draft-ietf-tls-md5-sha1-deprecate-04

Abstract

   The MD5 and SHA-1 hashing algorithms are steadily weakening in
   strength and their deprecation process should begin for their use in
   TLS 1.2 digital signatures.  However, this document does not
   deprecate SHA-1 in HMAC for record protection.  This document updates
   RFC 5246 and RFC 7525.

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
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   This Internet-Draft will expire on April 12, 2021.

Copyright Notice

   Copyright (c) 2020 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
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   to this document.  Code Components extracted from this document must

Velvindron, et al.       Expires April 12, 2021                 [Page 1]
Internet-Draft      draft-ietf-tls-md5-sha1-deprecate       October 2020

   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
     1.1.  Requirements Language . . . . . . . . . . . . . . . . . .   2
   2.  Signature Algorithms  . . . . . . . . . . . . . . . . . . . .   3
   3.  Certificate Request . . . . . . . . . . . . . . . . . . . . .   3
   4.  Server Key Exchange . . . . . . . . . . . . . . . . . . . . .   3
   5.  Certificate Verify  . . . . . . . . . . . . . . . . . . . . .   3
   6.  Updates to RFC5246  . . . . . . . . . . . . . . . . . . . . .   3
   7.  Updates to RFC7525  . . . . . . . . . . . . . . . . . . . . .   4
   8.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   4
   9.  Security Considerations . . . . . . . . . . . . . . . . . . .   5
   10. Acknowledgement . . . . . . . . . . . . . . . . . . . . . . .   5
   11. References  . . . . . . . . . . . . . . . . . . . . . . . . .   5
     11.1.  Normative References . . . . . . . . . . . . . . . . . .   5
     11.2.  Informative References . . . . . . . . . . . . . . . . .   5
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   6

1.  Introduction

   The usage of MD5 and SHA-1 for signature hashing in TLS 1.2 is
   specified in [RFC5246].  MD5 and SHA-1 have been proven to be
   insecure, subject to collision attacks [Wang].  In 2011, [RFC6151]
   detailed the security considerations, including collision attacks for
   MD5.  NIST formally deprecated use of SHA-1 in 2011
   [NISTSP800-131A-R2] and disallowed its use for digital signatures at
   the end of 2013, based on both the Wang, et. al, attack and the
   potential for brute-force attack.  In 2016, researchers from INRIA
   identified a new class of transcript collision attacks on TLS (and
   other protocols) that rely on efficient collision-finding algorithms
   on the underlying hash constructions [Transcript-Collision].
   Further, in 2017, researchers from Google and CWI Amsterdam
   [SHA-1-Collision] proved SHA-1 collision attacks were practical.
   This document updates [RFC5246] and [RFC7525] in such a way that MD5
   and SHA-1 MUST NOT be used for digital signatures.  However, this
   document does not deprecate SHA-1 in HMAC for record protection.

1.1.  Requirements Language

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
   "OPTIONAL" in this document are to be interpreted as described in BCP
   14 [RFC2119] [RFC8174] when, and only when, they appear in all
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