draft-ietf-lamps-cms-aes-gmac-alg-04.txt		draft-ietf-lamps-cms-aes-gmac-alg-05.txt
	Network Working Group R. Housley		Network Working Group R. Housley
	Internet-Draft Vigil Security		Internet-Draft Vigil Security
	Intended status: Standards Track 8 March 2021		Intended status: Standards Track 2 April 2021
	Expires: 9 September 2021		Expires: 4 October 2021
	Using the AES-GMAC Algorithm with the Cryptographic Message Syntax (CMS)		Using the AES-GMAC Algorithm with the Cryptographic Message Syntax (CMS)
	draft-ietf-lamps-cms-aes-gmac-alg-04		draft-ietf-lamps-cms-aes-gmac-alg-05
	Abstract		Abstract
	This document specifies the conventions for using the AES-GMAC		This document specifies the conventions for using the AES-GMAC
	Message Authentication Code algorithms with the Cryptographic Message		Message Authentication Code algorithms with the Cryptographic Message
	Syntax (CMS) as specified in RFC 5652.		Syntax (CMS) as specified in RFC 5652.
	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
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	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 9 September 2021.		This Internet-Draft will expire on 4 October 2021.
	Copyright Notice		Copyright Notice
	Copyright (c) 2021 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 (https://trustee.ietf.org/		Provisions Relating to IETF Documents (https://trustee.ietf.org/
	license-info) in effect on the date of publication of this document.		license-info) in effect on the date of publication of this document.
	Please review these documents carefully, as they describe your rights		Please review these documents carefully, as they describe your rights
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	3. Message Authentication Code Algorithms . . . . . . . . . . . 2		3. Message Authentication Code Algorithms . . . . . . . . . . . 2
	3.1. AES-GMAC . . . . . . . . . . . . . . . . . . . . . . . . 2		3.1. AES-GMAC . . . . . . . . . . . . . . . . . . . . . . . . 2
	4. Implementation Considerations . . . . . . . . . . . . . . . . 3		4. Implementation Considerations . . . . . . . . . . . . . . . . 3
	5. ASN.1 Module . . . . . . . . . . . . . . . . . . . . . . . . 4		5. ASN.1 Module . . . . . . . . . . . . . . . . . . . . . . . . 4
	6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5		6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5
	7. Security Considerations . . . . . . . . . . . . . . . . . . . 5		7. Security Considerations . . . . . . . . . . . . . . . . . . . 5
	8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 6		8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 6
	9. References . . . . . . . . . . . . . . . . . . . . . . . . . 6		9. References . . . . . . . . . . . . . . . . . . . . . . . . . 6
	9.1. Normative References . . . . . . . . . . . . . . . . . . 6		9.1. Normative References . . . . . . . . . . . . . . . . . . 6
	9.2. Informative References . . . . . . . . . . . . . . . . . 7		9.2. Informative References . . . . . . . . . . . . . . . . . 7
	Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 7		Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 8
	1. Introduction		1. Introduction
	This document specifies the conventions for using the AES-GMAC		This document specifies the conventions for using the AES-GMAC
	[AES][GCM] Message Authentication Code (MAC) algorithm with the		[AES][GCM] Message Authentication Code (MAC) algorithm with the
	Cryptographic Message Syntax (CMS) [RFC5652].		Cryptographic Message Syntax (CMS) [RFC5652].
	2. Terminology		2. Terminology
	The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",		The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
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	Within the scope of any content-authentication key, the AES-GMAC		Within the scope of any content-authentication key, the AES-GMAC
	nonce value MUST be unique. Use of a nonce value more than once		nonce value MUST be unique. Use of a nonce value more than once
	allows an attacker to generate valid AES-GMAC authentication codes		allows an attacker to generate valid AES-GMAC authentication codes
	for arbitrary messages, resulting in the loss of authentication as		for arbitrary messages, resulting in the loss of authentication as
	described in Appendix A of [GCM].		described in Appendix A of [GCM].
	Within the scope of any content-authentication key, the		Within the scope of any content-authentication key, the
	authentication tag length (MACLength) MUST be fixed.		authentication tag length (MACLength) MUST be fixed.
			If AES-GMAC is used as a building block in another algorithm (e.g.,
			as a pseudo-random function), AES-GMAC MUST be used only one time by
			that algorithm. For instance, AES-GMAC MUST NOT be used as the
			pseudo-random function for PBKDF2.
	When IV lengths other than 96 bits are used, the GHASH function is		When IV lengths other than 96 bits are used, the GHASH function is
	used to process the provided IV, which introduces a potential of IV		used to process the provided IV, which introduces a potential of IV
	collisions. However, IV collisions are not a concern with CMS		collisions. However, IV collisions are not a concern with CMS
	AuthenticatedData because a fresh content-authentication key is		AuthenticatedData because a fresh content-authentication key is
	usually generated for each message.		usually generated for each message.
	The probability of a successful forgery is close to 2^(-t), where t		The probability of a successful forgery is close to 2^(-t), where t
	is the number of bits in the authentication tag length (MACLength*8).		is the number of bits in the authentication tag length (MACLength*8).
	This nearly ideal authentication protection is achieved for CMS		This nearly ideal authentication protection is achieved for CMS
	AuthenticatedData when a fresh content-authentication key is		AuthenticatedData when a fresh content-authentication key is
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	weaker with time. As new cryptanalysis techniques are developed and		weaker with time. As new cryptanalysis techniques are developed and
	computing performance improves, the work factor to break a particular		computing performance improves, the work factor to break a particular
	cryptographic algorithm will reduce. Therefore, cryptographic		cryptographic algorithm will reduce. Therefore, cryptographic
	algorithm implementations should be modular allowing new algorithms		algorithm implementations should be modular allowing new algorithms
	to be readily inserted. That is, implementers should be prepared to		to be readily inserted. That is, implementers should be prepared to
	regularly update the set of algorithms in their implementations.		regularly update the set of algorithms in their implementations.
	More information is available in BCP 201 [RFC7696].		More information is available in BCP 201 [RFC7696].
	8. Acknowledgements		8. Acknowledgements
	Many thanks to Quynh Dang, Roman Danyliw, Tim Hollebeek, Ben Kaduk,		Many thanks to Hans Aschauer, Hendrik Brockhaus, Quynh Dang, Roman
	Mike Ounsworth, and Magnus Westerlund for their careful review and		Danyliw, Tim Hollebeek, Ben Kaduk, Mike Ounsworth, and Magnus
	thoughtful improvements.		Westerlund for their careful review and thoughtful improvements.
	9. References		9. References
	9.1. Normative References		9.1. Normative References
	[AES] National Institute of Standards and Technology (NIST),		[AES] National Institute of Standards and Technology (NIST),
	"Advanced Encryption Standard (AES)", FIPS		"Advanced Encryption Standard (AES)", FIPS
	Publication 197, November 2001.		Publication 197, November 2001.
	[GCM] Dworkin, M., "Recommendation for Block Cipher Modes of		[GCM] Dworkin, M., "Recommendation for Block Cipher Modes of
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