< draft-nir-ipsecme-chacha20-poly1305-04.txt		draft-nir-ipsecme-chacha20-poly1305-05.txt >
	Network Working Group Y. Nir		Network Working Group Y. Nir
	Internet-Draft Check Point		Internet-Draft Check Point
	Intended status: Standards Track June 1, 2014		Intended status: Standards Track November 24, 2014
	Expires: December 3, 2014		Expires: May 28, 2015
	ChaCha20, Poly1305 and their use in IPsec		ChaCha20, Poly1305 and their use in IPsec
	draft-nir-ipsecme-chacha20-poly1305-04		draft-nir-ipsecme-chacha20-poly1305-05
	Abstract		Abstract
	This document describes the use of the ChaCha20 stream cipher along		This document describes the use of the ChaCha20 stream cipher along
	with the Poly1305 authenticator, combined into an AEAD algorithm for		with the Poly1305 authenticator, combined into an AEAD algorithm for
	IPsec.		IPsec.
	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.
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	This Internet-Draft will expire on December 3, 2014.		This Internet-Draft will expire on May 28, 2015.
	Copyright Notice		Copyright Notice
	Copyright (c) 2014 IETF Trust and the persons identified as the		Copyright (c) 2014 IETF Trust and the persons identified as the
	document authors. All rights reserved.		document authors. All rights reserved.
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	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.
	Table of Contents		Table of Contents
	1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3		1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
	1.1. Conventions Used in This Document . . . . . . . . . . . . . 3		1.1. Conventions Used in This Document . . . . . . . . . . . . 2
	2. ESP_ChaCha20-Poly1305 for ESP . . . . . . . . . . . . . . . . . 3		2. ESP_ChaCha20-Poly1305 for ESP . . . . . . . . . . . . . . . . 3
	2.1. AAD Construction . . . . . . . . . . . . . . . . . . . . . 4		2.1. AAD Construction . . . . . . . . . . . . . . . . . . . . 4
	3. Use in IKEv2 . . . . . . . . . . . . . . . . . . . . . . . . . 4		3. Use in IKEv2 . . . . . . . . . . . . . . . . . . . . . . . . 4
	4. UI Suite . . . . . . . . . . . . . . . . . . . . . . . . . . . 5		4. UI Suite . . . . . . . . . . . . . . . . . . . . . . . . . . 4
	5. Security Considerations . . . . . . . . . . . . . . . . . . . . 5		5. Security Considerations . . . . . . . . . . . . . . . . . . . 5
	6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 6		6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5
	7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 6		7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 5
	8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 6		8. References . . . . . . . . . . . . . . . . . . . . . . . . . 6
	8.1. Normative References . . . . . . . . . . . . . . . . . . . 6		8.1. Normative References . . . . . . . . . . . . . . . . . . 6
	8.2. Informative References . . . . . . . . . . . . . . . . . . 7		8.2. Informative References . . . . . . . . . . . . . . . . . 6
	Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 8		Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 7
	1. Introduction		1. Introduction
	The Advanced Encryption Standard (AES - [FIPS-197]) has become the		The Advanced Encryption Standard (AES - [FIPS-197]) has become the
	gold standard in encryption. Its efficient design, wide		gold standard in encryption. Its efficient design, wide
	implementation, and hardware support allow for high performance in		implementation, and hardware support allow for high performance in
	many areas, including IPsec VPNs. On most modern platforms, AES is		many areas, including IPsec VPNs. On most modern platforms, AES is
	anywhere from 4x to 10x as fast as the previous most-used cipher,		anywhere from 4x to 10x as fast as the previous most-used cipher,
	3-key Data Encryption Standard (3DES - [FIPS-46]), which makes it not		3-key Data Encryption Standard (3DES - [FIPS-46]), which makes it not
	only the best choice, but the only choice.		only the best choice, but the only choice.
	skipping to change at page 3, line 40 ¶		skipping to change at page 3, line 10 ¶
	The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",		The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
	"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this		"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
	document are to be interpreted as described in [RFC2119].		document are to be interpreted as described in [RFC2119].
	2. ESP_ChaCha20-Poly1305 for ESP		2. ESP_ChaCha20-Poly1305 for ESP
	ESP_ChaCha20-Poly1305 is a combined mode algorithm, or AEAD. The		ESP_ChaCha20-Poly1305 is a combined mode algorithm, or AEAD. The
	construction follows the AEAD construction in section 2.7 of		construction follows the AEAD construction in section 2.7 of
	[chacha_poly]:		[chacha_poly]:
	o The IV is 64-bit, and is used as part of the nonce.		o The IV is 64-bit, and is used as part of the nonce.
	o A 32-bit sender ID is prepended to the 64-bit IV to form the 96-		o A 32-bit sender ID is prepended to the 64-bit IV to form the
	bit nonce. For regular IPsec, this is set to all zeros. IPsec		96-bit nonce. For regular IPsec, this is set to all zeros. IPsec
	extensions that allow multiple senders, such as GDOI ([RFC6407])		extensions that allow multiple senders, such as GDOI ([RFC6407])
	or [RFC6054] may set this to different values.		or [RFC6054] may set this to different values.
	o The encryption key is 256-bit.		o The encryption key is 256-bit.
	o The Internet Key Exchange protocol (IKE - [RFC5996]) generates a		o The Internet Key Exchange protocol (IKE - [RFC7296]) generates a
	bitstring called KEYMAT that is generated from a PRF. That KEYMAT		bitstring called KEYMAT that is generated from a PRF. That KEYMAT
	is divided into keys for encryption, message authentication and		is divided into keys for encryption, message authentication and
	whatever else is needed. For the ChaCha20 algorithm, 256 bits are		whatever else is needed. For the ChaCha20 algorithm, 256 bits are
	used for the key. TBD: do we want an extra 32 bits as salt for		used for the key. TBD: do we want an extra 32 bits as salt for
	the nonce like in GCM?		the nonce like in GCM?
	o The ChaCha20 encryption algorithm requires the following		o The ChaCha20 encryption algorithm requires the following
	parameters: a 256-bit key, a 96-bit nonce, and a 32-bit initial		parameters: a 256-bit key, a 96-bit nonce, and a 32-bit initial
	block counter. For ESP we set these as follows:		block counter. For ESP we set these as follows:
	* The key is set to the key mentioned above.		* The key is set to the key mentioned above.
	* The 96-bit nonce is formed from a concatenation of the 32-bit		* The 96-bit nonce is formed from a concatenation of the 32-bit
	sender ID and the 64-bit IV, as described above.		sender ID and the 64-bit IV, as described above.
	* The Initial Block Counter is set to one (1). The reason that		* The Initial Block Counter is set to one (1). The reason that
	one is used for the initial counter rather than zero is that		one is used for the initial counter rather than zero is that
	zero is reserved for generating the one-time Poly1305 key (see		zero is reserved for generating the one-time Poly1305 key (see
	below)		below)
	o As ChaCha20 is not a block cipher, no padding should be necessary.		o As ChaCha20 is not a block cipher, no padding should be necessary.
	However, in keeping with the specification in RFC 4303, the ESP		However, in keeping with the specification in RFC 4303, the ESP
	does have padding, so as to align the buffer to an integral		does have padding, so as to align the buffer to an integral
	skipping to change at page 5, line 36 ¶		skipping to change at page 5, line 9 ¶
	IKEv2:		IKEv2:
	Encryption ESP_ChaCha20-Poly1305		Encryption ESP_ChaCha20-Poly1305
	Integrity NULL		Integrity NULL
	Pseudo-random function HMAC-SHA-256 [RFC4868]		Pseudo-random function HMAC-SHA-256 [RFC4868]
	Diffie-Hellman group 256-bit random ECP group [RFC5903]		Diffie-Hellman group 256-bit random ECP group [RFC5903]
	HMAC-SHA-256 is used here because there is no natural way to use		HMAC-SHA-256 is used here because there is no natural way to use
	either ChaCha20 or Poly1305 as an IKEv2 PRF. See discussion in		either ChaCha20 or Poly1305 as an IKEv2 PRF. See discussion in
	section 2.7 of [chacha_poly].		section 2.7 of [chacha_poly].
			TBD: Do we want to define a special PRF function here? Something can
			be concocted from using ChaCha20 as the PRF function and Poly1305 for
			shortening keys, but somehow this looks unwieldy.
	TBD: Should we replace the Diffie-Hellman group with ED25519 ???		TBD: Should we replace the Diffie-Hellman group with ED25519 ???
	5. Security Considerations		5. Security Considerations
	The ChaCha20 cipher is designed to provide 256-bit security.		The ChaCha20 cipher is designed to provide 256-bit security.
	The Poly1305 authenticator is designed to ensure that forged messages		The Poly1305 authenticator is designed to ensure that forged messages
	are rejected with a probability of 1-(n/(2^102)) for a 16n-byte		are rejected with a probability of 1-(n/(2^102)) for a 16n-byte
	message, even after sending 2^64 legitimate messages, so it is SUF-		message, even after sending 2^64 legitimate messages, so it is SUF-
	CMA in the terminology of [AE].		CMA in the terminology of [AE].
	skipping to change at page 6, line 27 ¶		skipping to change at page 5, line 50 ¶
	IANA is requested to assign one value from the IKEv2 "Transform Type		IANA is requested to assign one value from the IKEv2 "Transform Type
	1 - Encryption Algorithm Transform IDs" registry, with name		1 - Encryption Algorithm Transform IDs" registry, with name
	ESP_ChaCha20-Poly1305, and this document as reference.		ESP_ChaCha20-Poly1305, and this document as reference.
	IANA is also requested to assign the identifier "VPN-C" with this		IANA is also requested to assign the identifier "VPN-C" with this
	document as reference from the "Cryptographic Suites for IKEv1,		document as reference from the "Cryptographic Suites for IKEv1,
	IKEv2, and IPsec" registry.		IKEv2, and IPsec" registry.
	7. Acknowledgements		7. Acknowledgements
	All of the algorithms in this document were designed by D. J.		All of the algorithms in this document were designed by D. J.
	Bernstein. The AEAD construction was designed by Adam Langley. The		Bernstein. The AEAD construction was designed by Adam Langley. The
	author would also like to thank Adam for helpful comments, as well as		author would also like to thank Adam for helpful comments, as well as
	Yaron Sheffer for telling me to write the algorithms draft.		Yaron Sheffer for telling me to write the algorithms draft.
	8. References		8. References
	8.1. Normative References		8.1. Normative References
	[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate		[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
	Requirement Levels", BCP 14, RFC 2119, March 1997.		Requirement Levels", BCP 14, RFC 2119, March 1997.
	[RFC4303] Kent, S., "IP Encapsulating Security Payload (ESP)",		[RFC4303] Kent, S., "IP Encapsulating Security Payload (ESP)", RFC
	RFC 4303, December 2005.		4303, December 2005.
	[RFC5282] Black, D. and D. McGrew, "Using Authenticated Encryption		[RFC5282] Black, D. and D. McGrew, "Using Authenticated Encryption
	Algorithms with the Encrypted Payload of the Internet Key		Algorithms with the Encrypted Payload of the Internet Key
	Exchange version 2 (IKEv2) Protocol", RFC 5282,		Exchange version 2 (IKEv2) Protocol", RFC 5282, August
	August 2008.		2008.
	[RFC5996] Kaufman, C., Hoffman, P., Nir, Y., and P. Eronen,
	"Internet Key Exchange Protocol Version 2 (IKEv2)",
	RFC 5996, September 2010.
	[RFC6054] McGrew, D. and B. Weis, "Using Counter Modes with		[RFC6054] McGrew, D. and B. Weis, "Using Counter Modes with
	Encapsulating Security Payload (ESP) and Authentication		Encapsulating Security Payload (ESP) and Authentication
	Header (AH) to Protect Group Traffic", RFC 6054,		Header (AH) to Protect Group Traffic", RFC 6054, November
	November 2010.		2010.
			[RFC7296] Kivinen, T., Kaufman, C., Hoffman, P., Nir, Y., and P.
			Eronen, "Internet Key Exchange Protocol Version 2
			(IKEv2)", RFC 7296, October 2014.
	[chacha_poly]		[chacha_poly]
	Langley, A. and Y. Nir, "ChaCha20 and Poly1305 for IETF		Langley, A. and Y. Nir, "ChaCha20 and Poly1305 for IETF
	protocols", draft-nir-cfrg-chacha20-poly1305-01 (work in		protocols", draft-nir-cfrg-chacha20-poly1305-01 (work in
	progress), January 2014.		progress), January 2014.
	8.2. Informative References		8.2. Informative References
	[AE] Bellare, M. and C. Namprempre, "Authenticated Encryption:		[AE] Bellare, M. and C. Namprempre, "Authenticated Encryption:
	Relations among notions and analysis of the generic		Relations among notions and analysis of the generic
	composition paradigm",		composition paradigm", 2000,
	<http://cseweb.ucsd.edu/~mihir/papers/oem.html>.		<http://cseweb.ucsd.edu/~mihir/papers/oem.html>.
	[FIPS-197]		[FIPS-197]
	National Institute of Standards and Technology, "Advanced		National Institute of Standards and Technology, "Advanced
	Encryption Standard (AES)", FIPS PUB 197, November 2001, <		Encryption Standard (AES)", FIPS PUB 197, November 2001,
	http://csrc.nist.gov/publications/fips/fips197/		<http://csrc.nist.gov/publications/fips/fips197/
	fips-197.pdf>.		fips-197.pdf>.
	[FIPS-46] National Institute of Standards and Technology, "Data		[FIPS-46] National Institute of Standards and Technology, "Data
	Encryption Standard", FIPS PUB 46-2, December 1993,		Encryption Standard", FIPS PUB 46-2, December 1993,
	<http://www.itl.nist.gov/fipspubs/fip46-2.htm>.		<http://www.itl.nist.gov/fipspubs/fip46-2.htm>.
	[RFC4106] Viega, J. and D. McGrew, "The Use of Galois/Counter Mode		[RFC4106] Viega, J. and D. McGrew, "The Use of Galois/Counter Mode
	(GCM) in IPsec Encapsulating Security Payload (ESP)",		(GCM) in IPsec Encapsulating Security Payload (ESP)", RFC
	RFC 4106, June 2005.		4106, June 2005.
	[RFC4308] Hoffman, P., "Cryptographic Suites for IPsec", RFC 4308,		[RFC4308] Hoffman, P., "Cryptographic Suites for IPsec", RFC 4308,
	December 2005.		December 2005.
	[RFC6379] Law, L. and J. Solinas, "Suite B Cryptographic Suites for		[RFC6379] Law, L. and J. Solinas, "Suite B Cryptographic Suites for
	IPsec", RFC 6379, October 2011.		IPsec", RFC 6379, October 2011.
	[RFC6407] Weis, B., Rowles, S., and T. Hardjono, "The Group Domain		[RFC6407] Weis, B., Rowles, S., and T. Hardjono, "The Group Domain
	of Interpretation", RFC 6407, October 2011.		of Interpretation", RFC 6407, October 2011.
	[standby-cipher]		[standby-cipher]
	McGrew, D., Grieco, A., and Y. Sheffer, "Selection of		McGrew, D., Grieco, A., and Y. Sheffer, "Selection of
	Future Cryptographic Standards",		Future Cryptographic Standards", draft-mcgrew-standby-
	draft-mcgrew-standby-cipher (work in progress).		cipher (work in progress), January 2013.
	Author's Address		Author's Address
	Yoav Nir		Yoav Nir
	Check Point Software Technologies Ltd.		Check Point Software Technologies Ltd.
	5 Hasolelim st.		5 Hasolelim st.
	Tel Aviv 6789735		Tel Aviv 6789735
	Israel		Israel
	Email: ynir.ietf@gmail.com		Email: ynir.ietf@gmail.com
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