< draft-ietf-tls-md5-sha1-deprecate-04.txt		draft-ietf-tls-md5-sha1-deprecate-05.txt >
	Internet Engineering Task Force L. Velvindron		Internet Engineering Task Force L. Velvindron
	Internet-Draft cyberstorm.mu		Internet-Draft cyberstorm.mu
	Updates: 5246 7525 (if approved) K. Moriarty		Updates: 5246 7525 (if approved) K. Moriarty
	Intended status: Standards Track Dell Technologies		Intended status: Standards Track Dell Technologies
	Expires: April 12, 2021 A. Ghedini		Expires: September 24, 2021 A. Ghedini
	Cloudflare Inc.		Cloudflare Inc.
	October 9, 2020		March 23, 2021
	Deprecating MD5 and SHA-1 signature hashes in TLS 1.2		Deprecating MD5 and SHA-1 signature hashes in TLS 1.2
	draft-ietf-tls-md5-sha1-deprecate-04		draft-ietf-tls-md5-sha1-deprecate-05
	Abstract		Abstract
	The MD5 and SHA-1 hashing algorithms are steadily weakening in		The MD5 and SHA-1 hashing algorithms are increasingly vulnerable to
	strength and their deprecation process should begin for their use in		attack and this document deprecates their use in TLS 1.2 digital
	TLS 1.2 digital signatures. However, this document does not		signatures. However, this document does not deprecate SHA-1 in HMAC
	deprecate SHA-1 in HMAC for record protection. This document updates		for record protection. This document updates RFC 5246 and RFC 7525.
	RFC 5246 and RFC 7525.
	Status of This Memo		Status of This Memo
	This Internet-Draft is submitted in full conformance with the		This Internet-Draft is submitted in full conformance with the
	provisions of BCP 78 and BCP 79.		provisions of BCP 78 and BCP 79.
	Internet-Drafts are working documents of the Internet Engineering		Internet-Drafts are working documents of the Internet Engineering
	Task Force (IETF). Note that other groups may also distribute		Task Force (IETF). Note that other groups may also distribute
	working documents as Internet-Drafts. The list of current Internet-		working documents as Internet-Drafts. The list of current Internet-
	Drafts is at https://datatracker.ietf.org/drafts/current/.		Drafts is at https://datatracker.ietf.org/drafts/current/.
	Internet-Drafts are draft documents valid for a maximum of six months		Internet-Drafts are draft documents valid for a maximum of six months
	and may be updated, replaced, or obsoleted by other documents at any		and may be updated, replaced, or obsoleted by other documents at any
	time. It is inappropriate to use Internet-Drafts as reference		time. It is inappropriate to use Internet-Drafts as reference
	material or to cite them other than as "work in progress."		material or to cite them other than as "work in progress."
	This Internet-Draft will expire on April 12, 2021.		This Internet-Draft will expire on September 24, 2021.
	Copyright Notice		Copyright Notice
	Copyright (c) 2020 IETF Trust and the persons identified as the		Copyright (c) 2021 IETF Trust and the persons identified as the
	document authors. All rights reserved.		document authors. All rights reserved.
	This document is subject to BCP 78 and the IETF Trust's Legal		This document is subject to BCP 78 and the IETF Trust's Legal
	Provisions Relating to IETF Documents		Provisions Relating to IETF Documents
	(https://trustee.ietf.org/license-info) in effect on the date of		(https://trustee.ietf.org/license-info) in effect on the date of
	publication of this document. Please review these documents		publication of this document. Please review these documents
	carefully, as they describe your rights and restrictions with respect		carefully, as they describe your rights and restrictions with respect
	to this document. Code Components extracted from this document must		to this document. Code Components extracted from this document must
	include Simplified BSD License text as described in Section 4.e of		include Simplified BSD License text as described in Section 4.e of
	the Trust Legal Provisions and are provided without warranty as		the Trust Legal Provisions and are provided without warranty as
	skipping to change at page 2, line 23 ¶		skipping to change at page 2, line 22 ¶
	3. Certificate Request . . . . . . . . . . . . . . . . . . . . . 3		3. Certificate Request . . . . . . . . . . . . . . . . . . . . . 3
	4. Server Key Exchange . . . . . . . . . . . . . . . . . . . . . 3		4. Server Key Exchange . . . . . . . . . . . . . . . . . . . . . 3
	5. Certificate Verify . . . . . . . . . . . . . . . . . . . . . 3		5. Certificate Verify . . . . . . . . . . . . . . . . . . . . . 3
	6. Updates to RFC5246 . . . . . . . . . . . . . . . . . . . . . 3		6. Updates to RFC5246 . . . . . . . . . . . . . . . . . . . . . 3
	7. Updates to RFC7525 . . . . . . . . . . . . . . . . . . . . . 4		7. Updates to RFC7525 . . . . . . . . . . . . . . . . . . . . . 4
	8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 4		8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 4
	9. Security Considerations . . . . . . . . . . . . . . . . . . . 5		9. Security Considerations . . . . . . . . . . . . . . . . . . . 5
	10. Acknowledgement . . . . . . . . . . . . . . . . . . . . . . . 5		10. Acknowledgement . . . . . . . . . . . . . . . . . . . . . . . 5
	11. References . . . . . . . . . . . . . . . . . . . . . . . . . 5		11. References . . . . . . . . . . . . . . . . . . . . . . . . . 5
	11.1. Normative References . . . . . . . . . . . . . . . . . . 5		11.1. Normative References . . . . . . . . . . . . . . . . . . 5
	11.2. Informative References . . . . . . . . . . . . . . . . . 5		11.2. Informative References . . . . . . . . . . . . . . . . . 6
	Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 6		Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 6
	1. Introduction		1. Introduction
	The usage of MD5 and SHA-1 for signature hashing in TLS 1.2 is		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		specified in [RFC5246]. MD5 and SHA-1 have been proven to be
	insecure, subject to collision attacks [Wang]. In 2011, [RFC6151]		insecure, subject to collision attacks [Wang]. In 2011, [RFC6151]
	detailed the security considerations, including collision attacks for		detailed the security considerations, including collision attacks for
	MD5. NIST formally deprecated use of SHA-1 in 2011		MD5. NIST formally deprecated use of SHA-1 in 2011
	[NISTSP800-131A-R2] and disallowed its use for digital signatures at		[NISTSP800-131A-R2] and disallowed its use for digital signatures at
	skipping to change at page 4, line 13 ¶		skipping to change at page 4, line 13 ¶
	supports SHA-256."		supports SHA-256."
	7. Updates to RFC7525		7. Updates to RFC7525
	[RFC7525], Recommendations for Secure Use of Transport Layer Security		[RFC7525], Recommendations for Secure Use of Transport Layer Security
	(TLS) and Datagram Transport Layer Security (DTLS) recommends use of		(TLS) and Datagram Transport Layer Security (DTLS) recommends use of
	SHA-256 as a minimum requirement. This update moves the minimum		SHA-256 as a minimum requirement. This update moves the minimum
	recommendation to use stronger language deprecating use of both SHA-1		recommendation to use stronger language deprecating use of both SHA-1
	and MD5. The prior text did not explicitly include MD5 or SHA-1; and		and MD5. The prior text did not explicitly include MD5 or SHA-1; and
	this text adds guidance to ensure that these algorithms have been		this text adds guidance to ensure that these algorithms have been
	deprecated..		deprecated.
	Section 4.3:		Section 4.3:
	OLD:		OLD:
	When using RSA, servers SHOULD authenticate using certificates with		When using RSA, servers SHOULD authenticate using certificates with
	at least a 2048-bit modulus for the public key. In addition, the use		at least a 2048-bit modulus for the public key. In addition, the use
	of the SHA-256 hash algorithm is RECOMMENDED (see [CAB-Baseline] for		of the SHA-256 hash algorithm is RECOMMENDED (see [CAB-Baseline] for
	more details). Clients SHOULD indicate to servers that they request		more details). Clients SHOULD indicate to servers that they request
	SHA-256, by using the "Signature Algorithms" extension defined in TLS		SHA-256, by using the "Signature Algorithms" extension defined in TLS
	skipping to change at page 4, line 44 ¶		skipping to change at page 4, line 44 ¶
	256, by using the "Signature Algorithms" extension defined in TLS		256, by using the "Signature Algorithms" extension defined in TLS
	1.2.		1.2.
	8. IANA Considerations		8. IANA Considerations
	The document updates the "TLS SignatureScheme" registry to change the		The document updates the "TLS SignatureScheme" registry to change the
	recommended status of SHA-1 based signature schemes to N (not		recommended status of SHA-1 based signature schemes to N (not
	recommended) as defined by [RFC8447]. The following entries are to		recommended) as defined by [RFC8447]. The following entries are to
	be updated:		be updated:
	+--------+----------------+-------------+-------------------+		+--------+----------------+-------------+--------------------+
	| Value | Description | Recommended | Reference |		| Value | Description | Recommended | Reference |
	+--------+----------------+-------------+-------------------+		+--------+----------------+-------------+--------------------+
	| 0x0201 | rsa_pkcs1_sha1 | N | [RFC8446][RFCTBD] |		| 0x0201 | rsa_pkcs1_sha1 | N | [RFC8446] [RFCTBD] |
	| 0x0203 | ecdsa_sha1 | N | [RFC8446][RFCTBD] |		| 0x0203 | ecdsa_sha1 | N | [RFC8446] [RFCTBD] |
	+--------+----------------+-------------+-------------------+		+--------+----------------+-------------+--------------------+
	Other entries of the resgistry remain the same.		Other entries of the registry remain the same.
	9. Security Considerations		9. Security Considerations
	Concerns with TLS 1.2 implementations falling back to SHA-1 is an		Concerns with TLS 1.2 implementations falling back to SHA-1 is an
	issue. This draft updates the TLS 1.2 specification to deprecate		issue. This document updates the TLS 1.2 specification to deprecate
	support for MD5 and SHA-1 for digital signatures. However, this		support for MD5 and SHA-1 for digital signatures. However, this
	document does not deprecate SHA-1 in HMAC for record protection.		document does not deprecate SHA-1 in HMAC for record protection.
	10. Acknowledgement		10. Acknowledgement
	The authors would like to thank Hubert Kario for his help in writing		The authors would like to thank Hubert Kario for his help in writing
	the initial draft. We are also grateful to Daniel Migault, Martin		the initial draft. We are also grateful to Daniel Migault, Martin
	Thomson and David Cooper for their feedback.		Thomson and David Cooper for their feedback.
	11. References		11. References
	skipping to change at page 5, line 42 ¶		skipping to change at page 5, line 42 ¶
	[RFC7525] Sheffer, Y., Holz, R., and P. Saint-Andre,		[RFC7525] Sheffer, Y., Holz, R., and P. Saint-Andre,
	"Recommendations for Secure Use of Transport Layer		"Recommendations for Secure Use of Transport Layer
	Security (TLS) and Datagram Transport Layer Security		Security (TLS) and Datagram Transport Layer Security
	(DTLS)", BCP 195, RFC 7525, DOI 10.17487/RFC7525, May		(DTLS)", BCP 195, RFC 7525, DOI 10.17487/RFC7525, May
	2015, <https://www.rfc-editor.org/info/rfc7525>.		2015, <https://www.rfc-editor.org/info/rfc7525>.
	[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC		[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
	2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,		2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
	May 2017, <https://www.rfc-editor.org/info/rfc8174>.		May 2017, <https://www.rfc-editor.org/info/rfc8174>.
			[RFC8446] Rescorla, E., "The Transport Layer Security (TLS) Protocol
			Version 1.3", RFC 8446, DOI 10.17487/RFC8446, August 2018,
			<https://www.rfc-editor.org/info/rfc8446>.
	[RFC8447] Salowey, J. and S. Turner, "IANA Registry Updates for TLS		[RFC8447] Salowey, J. and S. Turner, "IANA Registry Updates for TLS
	and DTLS", RFC 8447, DOI 10.17487/RFC8447, August 2018,		and DTLS", RFC 8447, DOI 10.17487/RFC8447, August 2018,
	<https://www.rfc-editor.org/info/rfc8447>.		<https://www.rfc-editor.org/info/rfc8447>.
	11.2. Informative References		11.2. Informative References
	[CAB-Baseline]		[CAB-Baseline]
	CA/Browser Forum, "Baseline Requirements for the Issuance		CA/Browser Forum, "Baseline Requirements for the Issuance
	and Management of Publicly-Trusted Certificates Version		and Management of Publicly-Trusted Certificates Version
	1.1.6", 2013, <https://www.cabforum.org/documents.html>.		1.1.6", 2013, <https://www.cabforum.org/documents.html>.
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