< draft-ietf-curdle-cms-chacha20-poly1305-04.txt		draft-ietf-curdle-cms-chacha20-poly1305-05.txt >
	Internet-Draft R. Housley		Internet-Draft R. Housley
	Intended status: Standards Track Vigil Security		Intended status: Standards Track Vigil Security
	Expires: 1 June 2017 1 December 2016		Expires: 6 July 2017 6 January 2017
	Using ChaCha20-Poly1305 Authenticated Encryption		Using ChaCha20-Poly1305 Authenticated Encryption
	in the Cryptographic Message Syntax (CMS)		in the Cryptographic Message Syntax (CMS)
	<draft-ietf-curdle-cms-chacha20-poly1305-04.txt>		<draft-ietf-curdle-cms-chacha20-poly1305-05.txt>
	Abstract		Abstract
	This document describes the conventions for using ChaCha20-Poly1305		This document describes the conventions for using ChaCha20-Poly1305
	Authenticated Encryption in the Cryptographic Message Syntax (CMS).		Authenticated Encryption in the Cryptographic Message Syntax (CMS).
	ChaCha20-Poly1305 is an authenticated encryption algorithm		ChaCha20-Poly1305 is an authenticated encryption algorithm
	constructed of the ChaCha stream cipher and Poly1305 authenticator.		constructed of the ChaCha stream cipher and Poly1305 authenticator.
	Status of This Memo		Status of This Memo
	skipping to change at page 1, line 34 ¶		skipping to change at page 1, line 34 ¶
	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-
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	and may be updated, replaced, or obsoleted by other documents at any		and may be updated, replaced, or obsoleted by other documents at any
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	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 1 June 2017.		This Internet-Draft will expire on 6 July 2017.
	Copyright Notice		Copyright Notice
	Copyright (c) 2016 IETF Trust and the persons identified as the		Copyright (c) 2016 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
	(http://trustee.ietf.org/license-info) in effect on the date of		(http://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
	described in the Simplified BSD License.		described in the Simplified BSD License.
	1. Introduction		1. Introduction
	This document specifies the conventions for using the		This document specifies the conventions for using ChaCha20-Poly1305
	ChaCha20-Poly1305 Authenticated Encryption as the content-		Authenticated Encryption with the Cryptographic Message Syntax (CMS)
	authenticated-encryption algorithm with the Cryptographic Message		[CMS] authenticated-enveloped-data content type [AUTHENV].
	Syntax (CMS) [CMS] authenticated-enveloped-data content type
	[AUTHENV].
	ChaCha [CHACHA] is a stream cipher developed by D. J. Bernstein in		ChaCha [CHACHA] is a stream cipher developed by D. J. Bernstein in
	2008. It is a refinement of Salsa20, which is one of the ciphers in		2008. It is a refinement of Salsa20, which is one of the ciphers in
	the eSTREAM portfolio [ESTREAM].		the eSTREAM portfolio [ESTREAM].
	ChaCha20 is the 20-round variant of ChaCha; it requires a 256-bit key		ChaCha20 is the 20-round variant of ChaCha; it requires a 256-bit key
	and a 96-bit nonce. ChaCha20 is described in [FORIETF].		and a 96-bit nonce. [FORIETF] provides a detailed algorithm
			description, examples, and test vectors of ChaCha20.
	Poly1305 [POLY1305] is a Wegman-Carter, one-time authenticator		Poly1305 [POLY1305] is a Wegman-Carter, one-time authenticator
	designed by D. J. Bernstein. Poly1305 produces a 16-byte		designed by D. J. Bernstein. Poly1305 produces a 16-byte
	authentication tag; it requires a 256-bit, single-use key. Poly1305		authentication tag; it requires a 256-bit, single-use key. [FORIETF]
	is also described in [FORIETF].		also provides a detailed algorithm description, examples, and test
			vectors of Poly1305.
	ChaCha20 and Poly1305 have been designed for high performance		ChaCha20 and Poly1305 have been designed for high performance
	software implementations. They can typically be implemented with few		software implementations. They can typically be implemented with few
	resources and inexpensive operations, making them suitable on a wide		resources and inexpensive operations, making them suitable on a wide
	range of systems. They have also been designed to minimize leakage		range of systems. They have also been designed to minimize leakage
	of information through side channels.		of information through side channels.
	1.1. The ChaCha20 and Poly1305 AEAD Construction		1.1. The ChaCha20 and Poly1305 AEAD Construction
	ChaCha20 and Poly1305 have been combined to create an Authenticated		ChaCha20 and Poly1305 have been combined to create an Authenticated
	skipping to change at page 4, line 15 ¶		skipping to change at page 4, line 15 ¶
	3. Using the AEAD_CHACHA20_POLY1305 Algorithm with AuthEnvelopedData		3. Using the AEAD_CHACHA20_POLY1305 Algorithm with AuthEnvelopedData
	This section specifies the conventions employed by CMS		This section specifies the conventions employed by CMS
	implementations that support the authenticated-enveloped-data content		implementations that support the authenticated-enveloped-data content
	type and the AEAD_CHACHA20_POLY1305 algorithm.		type and the AEAD_CHACHA20_POLY1305 algorithm.
	The AEAD_CHACHA20_POLY1305 algorithm identifier is located in the		The AEAD_CHACHA20_POLY1305 algorithm identifier is located in the
	AuthEnvelopedData EncryptedContentInfo contentEncryptionAlgorithm		AuthEnvelopedData EncryptedContentInfo contentEncryptionAlgorithm
	field.		field.
	The AEAD_CHACHA20_POLY1305 algorithm is used to encipher the content		The AEAD_CHACHA20_POLY1305 algorithm is used to authenticate the
	located in the AuthEnvelopedData EncryptedContentInfo		attributes located in the AuthEnvelopedData authAttrs field, if any
	encryptedContent field and to provide the message authentication code		are present, encipher the content located in the AuthEnvelopedData
	(MAC) located in the AuthEnvelopedData mac field. The ciphertext and		EncryptedContentInfo encryptedContent field, and to provide the
	the MAC are the two outputs of the AEAD_CHACHA20_POLY1305 Algorithm.		message authentication code (MAC) located in the AuthEnvelopedData
	Note that the MAC, which is called the authentication tag in		mac field. The authenticated attributes are DER encoded to produce
	[FORIETF], provides integrity protection for both the		the AAD input value to the AEAD_CHACHA20_POLY1305 algorithm. The
	AuthEnvelopedData authAttrs and the AuthEnvelopedData		ciphertext and the MAC are the two outputs of the
			AEAD_CHACHA20_POLY1305 algorithm. Note that the MAC, which is called
			the authentication tag in [FORIETF], provides integrity protection
			for both the AuthEnvelopedData authAttrs and the AuthEnvelopedData
	EncryptedContentInfo encryptedContent.		EncryptedContentInfo encryptedContent.
	Neither the plaintext content nor the optional AAD inputs need to be		Neither the plaintext content nor the optional AAD inputs need to be
	padded prior to invoking the AEAD_CHACHA20_POLY1305 algorithm.		padded prior to invoking the AEAD_CHACHA20_POLY1305 algorithm.
	There is one algorithm identifier for the AEAD_CHACHA20_POLY1305		There is one algorithm identifier for the AEAD_CHACHA20_POLY1305
	algorithm:		algorithm:
	id-alg-AEADChaCha20Poly1305 OBJECT IDENTIFIER ::=		id-alg-AEADChaCha20Poly1305 OBJECT IDENTIFIER ::=
	{ iso(1) member-body(2) us(840) rsadsi(113549) pkcs(1)		{ iso(1) member-body(2) us(840) rsadsi(113549) pkcs(1)
	skipping to change at page 6, line 27 ¶		skipping to change at page 6, line 30 ¶
	generators (PRNGs) to generate cryptographic keys can result in		generators (PRNGs) to generate cryptographic keys can result in
	little or no security. An attacker may find it much easier to		little or no security. An attacker may find it much easier to
	reproduce the PRNG environment that produced the keys, searching the		reproduce the PRNG environment that produced the keys, searching the
	resulting small set of possibilities, rather than brute force		resulting small set of possibilities, rather than brute force
	searching the whole key space. The generation of quality random		searching the whole key space. The generation of quality random
	numbers is difficult. RFC 4086 [RANDOM] offers important guidance in		numbers is difficult. RFC 4086 [RANDOM] offers important guidance in
	this area.		this area.
	7. Acknowledgements		7. Acknowledgements
	Thanks to Jim Schaad, Daniel Migault, and Stephen Farrell for their		Thanks to Jim Schaad, Daniel Migault, Stephen Farrell, Yoav Nir, and
	review and insightful comments.		Niclas Comstedt for their review and insightful comments.
	8. Normative References		8. Normative References
	[AUTHENV] Housley, R., "Cryptographic Message Syntax (CMS)		[AUTHENV] Housley, R., "Cryptographic Message Syntax (CMS)
	Authenticated-Enveloped-Data Content Type", RFC 5083,		Authenticated-Enveloped-Data Content Type", RFC 5083,
	November 2007.		November 2007.
	[CMS] Housley, R., "Cryptographic Message Syntax (CMS)", RFC		[CMS] Housley, R., "Cryptographic Message Syntax (CMS)", RFC
	5652, September 2009.		5652, September 2009.
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