Deprecating MD5 and SHA-1 signature hashes in TLS 1.2
draft-lvelvindron-tls-md5-sha1-deprecate-05
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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 EMC
Expires: November 30, 2019 A. Ghedini
Cloudflare Inc.
May 29, 2019
Deprecating MD5 and SHA-1 signature hashes in TLS 1.2
draft-lvelvindron-tls-md5-sha1-deprecate-05
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.
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 November 30, 2019.
Copyright Notice
Copyright (c) 2019 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 November 30, 2019 [Page 1]
Internet-Draft draft-lvelvindron-tls-md5-sha1-deprecate May 2019
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 . . . . . . . . . . . . . . . . . . . . 2
3. Certificate Request . . . . . . . . . . . . . . . . . . . . . 3
4. Server Key Exchange . . . . . . . . . . . . . . . . . . . . . 3
5. Certificate Verify . . . . . . . . . . . . . . . . . . . . . 3
6. Updates to RFC5246 . . . . . . . . . . . . . . . . . . . . . 3
7. Updates to RFC7525 . . . . . . . . . . . . . . . . . . . . . 3
8. Security Considerations . . . . . . . . . . . . . . . . . . . 4
9. Acknowledgement . . . . . . . . . . . . . . . . . . . . . . . 4
10. References . . . . . . . . . . . . . . . . . . . . . . . . . 4
10.1. Normative References . . . . . . . . . . . . . . . . . . 4
10.2. Informative References . . . . . . . . . . . . . . . . . 4
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 5
1. Introduction
The usage of MD5 and SHA-1 for signature hashing in TLS 1.2 is
specified in RFC 5246 [RFC5246]. MD5 and SHA-1 have been proven to
be insecure, subject to collision attacks. RFC 6151 [RFC6151]
details the security considerations, including collision attacks for
MD5, published in 2011. 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. Further, in 2017,
researchers from Google and CWI Amsterdam [SHA-1-Collision] proved
SHA-1 collision attacks were practical. This document updates
RFC 5246 [RFC5246] and RFC7525 [RFC7525] in such as way that MD5 and
SHA1 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", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC 2119 [RFC2119].
2. Signature Algorithms
Clients SHOULD NOT include MD5 and SHA-1 in signature_algorithms
extension. If a client does not send a signature_algorithms
extension, then the server MUST abort the handshake and send a
handshake_failure alert.
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