Deprecating MD5 and SHA-1 signature hashes in TLS 1.2
draft-ietf-tls-md5-sha1-deprecate-06

Document Type Active Internet-Draft (tls WG)
Authors Loganaden Velvindron  , Kathleen Moriarty  , Alessandro Ghedini 
Last updated 2021-03-29
Replaces draft-lvelvindron-tls-md5-sha1-deprecate
Stream Internet Engineering Task Force (IETF)
Intended RFC status Proposed Standard
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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)
IESG IESG state Waiting for Writeup::AD Followup
Action Holders
Kathleen Moriarty  for 44 days
Loganaden Velvindron  for 44 days
Alessandro Ghedini  for 44 days
Consensus Boilerplate Yes
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Responsible AD Roman Danyliw
Send notices to joe@salowey.net, loganaden@gmail.com
IANA IANA review state Version Changed - Review Needed
IANA expert review state Expert Reviews OK
Internet Engineering Task Force                            L. Velvindron
Internet-Draft                                             cyberstorm.mu
Updates: 5246 7525 (if approved)                             K. Moriarty
Intended status: Standards Track                       Dell Technologies
Expires: September 30, 2021                                   A. Ghedini
                                                         Cloudflare Inc.
                                                          March 29, 2021

         Deprecating MD5 and SHA-1 signature hashes in TLS 1.2
                  draft-ietf-tls-md5-sha1-deprecate-06

Abstract

   The MD5 and SHA-1 hashing algorithms are increasingly vulnerable to
   attack and this document deprecates 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
   Task Force (IETF).  Note that other groups may also distribute
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   Drafts is at https://datatracker.ietf.org/drafts/current/.

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on September 30, 2021.

Copyright Notice

   Copyright (c) 2021 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
   Provisions Relating to IETF Documents
   (https://trustee.ietf.org/license-info) in effect on the date of
   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect
   to this document.  Code Components extracted from this document must
   include Simplified BSD License text as described in Section 4.e of

Velvindron, et al.     Expires September 30, 2021               [Page 1]
Internet-Draft      draft-ietf-tls-md5-sha1-deprecate         March 2021

   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

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 . . . . . . . . . . . . . . . . .   6
   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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