< draft-mavrogiannopoulos-chacha-tls-00.txt		draft-mavrogiannopoulos-chacha-tls-01.txt >
	Network Working Group N. Mavrogiannopoulos		Network Working Group A. Langley
	Internet-Draft Red Hat		Internet-Draft W. Chang
	Intended status: Informational J. Strombergson		Updates: 5246, 6347 Google Inc
	Expires: June 9, 2014 Secworks Sweden AB		(if approved) N. Mavrogiannopoulos
			Intended status: Standards Track Red Hat
			Expires: July 28, 2014 J. Strombergson
			Secworks Sweden AB
	S. Josefsson		S. Josefsson
	SJD AB		SJD AB
	December 6, 2013		January 24, 2014
	The ChaCha Stream Cipher for Transport Layer Security		The ChaCha Stream Cipher for Transport Layer Security
	draft-mavrogiannopoulos-chacha-tls-00		draft-mavrogiannopoulos-chacha-tls-01
	Abstract		Abstract
	This document describe how the Chacha stream cipher can be used in		This document describes the use of the ChaCha stream cipher with
	the Transport Layer Security (TLS) and Datagram Transport Layer		HMAC-SHA1 and Poly1305 in Transport Layer Security (TLS) and Datagram
	Security (DTLS) protocols.		Transport Layer Security (DTLS) protocols.
	Status of this Memo		Status of this Memo
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	provisions of BCP 78 and BCP 79.		provisions of BCP 78 and BCP 79.
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	Copyright Notice		Copyright Notice
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	Table of Contents		Table of Contents
	1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3		1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
	2. Chacha Cipher Suites . . . . . . . . . . . . . . . . . . . . . 4		2. The ChaCha Cipher . . . . . . . . . . . . . . . . . . . . . . 4
	2.1. Chacha Cipher Suites with HMAC-SHA1 . . . . . . . . . . . 4		3. The Poly1305 Authenticator . . . . . . . . . . . . . . . . . . 6
	3. The TLS GenericStreamCipher . . . . . . . . . . . . . . . . . 5		4. ChaCha20 Cipher Suites . . . . . . . . . . . . . . . . . . . . 7
	4. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 6		4.1. ChaCha20 Cipher Suites with HMAC-SHA1 . . . . . . . . . . 7
	5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 7		4.2. ChaCha20 Cipher Suites with Poly1305 . . . . . . . . . . . 7
	6. Security Considerations . . . . . . . . . . . . . . . . . . . 8		5. Updates to the TLS Standard Stream Cipher . . . . . . . . . . 10
	7. References . . . . . . . . . . . . . . . . . . . . . . . . . . 9		6. Updates to DTLS . . . . . . . . . . . . . . . . . . . . . . . 11
	7.1. Normative References . . . . . . . . . . . . . . . . . . . 9		7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 12
	7.2. Informative References . . . . . . . . . . . . . . . . . . 9		8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 13
	Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 11		9. Security Considerations . . . . . . . . . . . . . . . . . . . 14
			10. References . . . . . . . . . . . . . . . . . . . . . . . . . . 15
			10.1. Normative References . . . . . . . . . . . . . . . . . . . 15
			10.2. Informative References . . . . . . . . . . . . . . . . . . 15
			Appendix A. Test vectors . . . . . . . . . . . . . . . . . . . . 17
			A.1. ChaCha20 . . . . . . . . . . . . . . . . . . . . . . . . . 17
			A.2. Poly1305 . . . . . . . . . . . . . . . . . . . . . . . . . 18
			A.3. AEAD_CHACHA20_POLY1305 . . . . . . . . . . . . . . . . . . 18
			Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 20
	1. Introduction		1. Introduction
	This document describe how the Chacha stream cipher can be used in		This document describes the use of the ChaCha stream cipher in the
	the Transport Layer Security (TLS) version 1.0 [RFC2246], TLS version		Transport Layer Security (TLS) version 1.0 [RFC2246], TLS version 1.1
	1.1 [RFC4346], and TLS version 1.2 [RFC5246] protocols, as well as in		[RFC4346], and TLS version 1.2 [RFC5246] protocols, as well as in the
	the Datagram Transport Layer Security (DTLS) versions 1.0 [RFC4347]		Datagram Transport Layer Security (DTLS) versions 1.0 [RFC4347] and
	and 1.2 [RFC6347]. It can also be used with Secure Sockets Layer		1.2 [RFC6347]. It can also be used with Secure Sockets Layer (SSL)
	(SSL) version 3.0 [RFC6101].		version 3.0 [RFC6101].
	Chacha [CHACHASPEC] is a stream cipher that has been designed for		ChaCha [CHACHA] is a stream cipher that has been designed for high
	high performance in software implementations. The cipher has compact		performance in software implementations. The cipher has compact
	implementation and uses few resources and inexpensive operations that		implementation and uses few resources and inexpensive operations that
	makes it suitable for implementation on a wide range of		makes it suitable for implementation on a wide range of
	architectures. It has been designed to prevent leakage of		architectures. It has been designed to prevent leakage of
	information through side channel analysis, has a simple and fast key		information through side channel analysis, has a simple and fast key
	setup and provides good overall performance. It is a variant of		setup and provides good overall performance. It is a variant of
	Salsa20 [SALSA20SPEC] which is one of the selected ciphers in the		Salsa20 [SALSA20SPEC] which is one of the selected ciphers in the
	eSTREAM portfolio [ESTREAM].		eSTREAM portfolio [ESTREAM].
	Recent attacks [CBC-ATTACK] have indicated problems with CBC-mode		Recent attacks [CBC-ATTACK] have indicated problems with CBC-mode
	cipher suites in TLS and DTLS as well as issues with the only		cipher suites in TLS and DTLS as well as issues with the only
	supported stream cipher (RC4) [RC4-ATTACK]. While the existing AEAD		supported stream cipher (RC4) [RC4-ATTACK]. While the existing AEAD
	ciphersuites address these issues, concerns about their performance,		(AES-GCM) ciphersuites address some of these issues, concerns about
	on general purpose CPUs, are sometimes raised [AEAD-PERFORMANCE].		the performance and ease of software implementation are sometimes
	Moreover, the DTLS protocol cannot take advantage of the fast RC4		raised.
	stream cipher because it does not provide random access in the key
	stream.
	Therefore, a new stream cipher to replace RC4 and address all the		Therefore, a new stream cipher to replace RC4 and address all the
	previous issues is needed. It is the purpose of this document to		previous issues is needed. It is the purpose of this document to
	describe a secure stream cipher for both TLS and DTLS that is		describe a secure stream cipher for both TLS and DTLS that is
	comparable to RC4 in speed on a wide range of platforms.		comparable to RC4 in speed on a wide range of platforms and can be
			implemented easily without being vulnerable to software side-channel
			attacks.
	2. Chacha Cipher Suites		2. The ChaCha Cipher
	The variant of Chacha used in this draft is Chacha with 20 rounds and		ChaCha [CHACHA] is a stream cipher developed by D. J. Bernstein in
	a 256 bit key. This is the conservative with respect to security		2008. It is a refinement of Salsa20 and was used as the core of the
	variant of the Chacha family. Test vectors for this cipher can be		SHA-3 finalist, BLAKE.
	found at [I-D.strombergson-chacha-test-vectors].
			The variant of ChaCha used in this document is ChaCha with 20 rounds
			and a 256 bit key, which will be referred to as ChaCha20 in the rest
			of this document. This is the conservative variant (with respect to
			security) of the ChaCha family.
			ChaCha maps 16, 32-bit input words to 16, 32-bit output words. By
			convention, 8 of the input words consist of a 256-bit key, 4 are
			constants and the remaining four are a nonce and block counter. The
			output words are converted to bytes and XORed with the plaintext to
			produce ciphertext. In order to generate sufficient output bytes to
			XOR with the whole plaintext, the block counter is incremented and
			ChaCha is run again, as many times as needed, for up to 2^70 bytes of
			output.
			ChaCha operates on a state of 16, 32-bit words which are initialised
			from the input words. The first four input words are constants:
			(0x61707865, 0x3320646e, 0x79622d32, 0x6b206574)
			Input words 4 through 11 are taken from the 256-bit key by reading
			the bytes in little-endian order, in 4-byte chunks. Input words 12
			and 13 are a block counter, with word 12 overflowing into word 13.
			Lastly, words 14 and 15 are taken from an 8-byte nonce, again by
			reading the bytes in little-endian order, in 4-byte chunks. The
			block counter words are initially zero.
			ChaCha20 consists of 20 rounds, alternating between "column" rounds
			and "diagonal" rounds. Each round applies the following "quarter-
			round" function four times, to a different set of words each time.
			The quarter-round function updates 4, 32-bit words (a, b, c, d) as
			follows, where <<< is a bitwise, left rotation:
			a += b; d ^= a; d <<<= 16;
			c += d; b ^= c; b <<<= 12;
			a += b; d ^= a; d <<<= 8;
			c += d; b ^= c; b <<<= 7;
			The 16 words are conceptually arranged in a four by four grid with
			the first word in the top-left position and the fourth word in the
			top-right position. The "column" rounds then apply the quarter-round
			function to the four columns, from left to right. The "diagonal"
			rounds apply the quarter-round to the top-left, bottom-right
			diagonal, followed by the pattern shifted one place to the right, for
			three more quarter-rounds.
			Specifically, a column round applies the quarter-round function to
			the following indexes: (0, 4, 8, 12), (1, 5, 9, 13), (2, 6, 10, 14),
			(3, 7, 11, 15). A diagonal round applies it to these indexes: (0, 5,
			10, 15), (1, 6, 11, 12), (2, 7, 8, 13), (3, 4, 9, 14).
			After 20 rounds of the above processing, the original 16 input words
			are added to the 16 words to form the 16 output words.
			The 64 output bytes are generated from the 16 output words by
			serializing them in little-endian order and concatenating the
			results.
			Test vectors for this cipher can be found in Appendix A.1.
			3. The Poly1305 Authenticator
			Poly1305 [POLY1305] is a Wegman-Carter, one-time authenticator
			designed by D. J. Bernstein. Poly1305 takes a 32-byte, one-time key
			and a message and produces a 16-byte tag that authenticates the
			message such that an attacker has a negligible chance of producing a
			valid tag for an inauthentic message.
			The first 16 bytes of the one-time key form an integer, _r_, as
			follows: the top four bits of the bytes at indexes 3, 7, 11 and 15
			are cleared, the bottom 2 bits of the bytes at indexes 4, 8 and 12
			are cleared and the 16 bytes are taken as a little-endian value.
			An accumulator is set to zero. For each chunk of 16 bytes from the
			input message, a byte with value 1 is appended and the 17 bytes are
			treated as a little-endian number. If the last chunk has less than
			16 bytes then zero bytes are appended after the 1 byte is appended
			until there are 17 bytes. The value is added to the accumulator and
			then the accumulator is multiplied by _r_, all mod 2^130 - 5.
			Finally the last 16 bytes of the one-time key are treated as a
			little-endian number and added to the accumulator, mod 2^128. The
			result is serialised as a little-endian number, producing the 16 byte
			tag. Note that the original specification of Poly1305 used a
			different construction with AES to generate the constant term of the
			polynomial from a counter nonce. For a more recent treatment that
			avoids the use of a block cipher in this fashion, as is done here,
			see section 9 of the NaCl specification [NACLCRYPTO].
			Test vectors for this authenticator can be found in Appendix A.2.
			4. ChaCha20 Cipher Suites
	In the next sections different ciphersuites are defined that utilize		In the next sections different ciphersuites are defined that utilize
	the Chacha cipher combined with various MAC methods.		the ChaCha20 cipher combined with various message authentication
			methods.
	In all cases, the pseudorandom function (PRF) for TLS 1.2 is the TLS		In all cases, the pseudorandom function (PRF) for TLS 1.2 is the TLS
	PRF with SHA-256 as the hash function. When used with TLS versions		PRF with SHA-256 as the hash function. When used with TLS versions
	prior to 1.2, the PRF is calculated as specified in the appropriate		prior to 1.2, the PRF is calculated as specified in the appropriate
	version of the TLS specification.		version of the TLS specification.
	2.1. Chacha Cipher Suites with HMAC-SHA1		The RSA, DHE_RSA, ECDHE_RSA, ECDHE_ECDSA, PSK, DHE_PSK, RSA_PSK,
			ECDHE_PSK key exchanges are performed as defined in [RFC5246],
			[RFC4492], and [RFC5489].
	The following CipherSuites are defined: (note that the third column		4.1. ChaCha20 Cipher Suites with HMAC-SHA1
	contains the suggested to IANA ciphersuite numbers)
	TLS_RSA_WITH_CHACHA_SHA1 = {0xTBD, 0xTBD} {0xE5, 0x00}		The following CipherSuites are defined.
	TLS_ECDHE_RSA_WITH_CHACHA_SHA1 = {0xTBD, 0xTBD} {0xE5, 0x01}
	TLS_ECDHE_ECDSA_WITH_CHACHA_SHA1 = {0xTBD, 0xTBD} {0xE5, 0x02}
	TLS_PSK_WITH_CHACHA_SHA1 = {0xTBD, 0xTBD} {0xE5, 0x03}		TLS_RSA_WITH_CHACHA20_SHA = {0xTBD, 0xTBD} {0xCC, 0x20}
	TLS_ECDHE_PSK_WITH_CHACHA_SHA1 = {0xTBD, 0xTBD} {0xE5, 0x04}		TLS_ECDHE_RSA_WITH_CHACHA20_SHA = {0xTBD, 0xTBD} {0xCC, 0x21}
	TLS_RSA_PSK_WITH_CHACHA_SHA1 = {0xTBD, 0xTBD} {0xE5, 0x05}		TLS_ECDHE_ECDSA_WITH_CHACHA20_SHA = {0xTBD, 0xTBD} {0xCC, 0x22}
	TLS_DHE_PSK_WITH_CHACHA_SHA1 = {0xTBD, 0xTBD} {0xE5, 0x06}		TLS_DHE_RSA_WITH_CHACHA20_SHA = {0xTBD, 0xTBD} {0xCC, 0x23}
	TLS_DHE_RSA_WITH_CHACHA_SHA1 = {0xTBD, 0xTBD} {0xE5, 0x07}		TLS_DHE_PSK_WITH_CHACHA20_SHA = {0xTBD, 0xTBD} {0xCC, 0x24}
	Note that Chacha requires a 64-bit nonce. That nonce is updated on		TLS_PSK_WITH_CHACHA20_SHA = {0xTBD, 0xTBD} {0xCC, 0x25}
			TLS_ECDHE_PSK_WITH_CHACHA20_SHA = {0xTBD, 0xTBD} {0xCC, 0x26}
			TLS_RSA_PSK_WITH_CHACHA20_SHA = {0xTBD, 0xTBD} {0xCC, 0x27}
			Note that ChaCha20 requires a 64-bit nonce. That nonce is updated on
	the encryption of every TLS record, and is set to be the 64-bit TLS		the encryption of every TLS record, and is set to be the 64-bit TLS
	record sequence number. In case of DTLS the 64-bit nonce is formed		record sequence number. In case of DTLS the 64-bit nonce is formed
	as the concatenation of the 16-bit epoch with the 48-bit sequence		as the concatenation of the 16-bit epoch with the 48-bit sequence
	number.		number.
	The RSA, DHE_RSA, ECDHE_RSA, ECDHE_ECDSA, PSK, DHE_PSK, RSA_PSK,
	ECDHE_PSK key exchanges are performed as defined in [RFC5246],
	[RFC4492], and [RFC5489].
	The MAC algorithm used in the ciphersuites above is HMAC-SHA1		The MAC algorithm used in the ciphersuites above is HMAC-SHA1
	[RFC6234].		[RFC6234].
	3. The TLS GenericStreamCipher		4.2. ChaCha20 Cipher Suites with Poly1305
	The ciphersuites defined in this document differ from the TLS RC4		The ChaCha20 and Poly1305 primitives are built into an AEAD algorithm
	ciphersuites that have been the basis for the definition of		[RFC5116], AEAD_CHACHA20_POLY1305, that takes a 32 byte key and 8
	GenericStreamCipher. Unlike RC4, Chacha requires a nonce per record.		byte nonce as follows.
	This however, does not affect the description of the
	GenericStreamCipher if one assumes that a nonce is optional and
	depends on the cipher's characteristics (in that case RC4 uses a 0
	byte nonce, and Chacha an 8-byte nonce).
	As specified in TLS [RFC5246] the MAC is computed before encryption		ChaCha20 is run with the given key and nonce and with the two counter
	and the stream cipher encrypts the entire block, including the MAC.		words set to zero. The first 32 bytes of the 64 byte output are
			saved to become the one-time key for Poly1305. The remainder of the
			output is discarded. The first counter input word is set to one and
			the plaintext is encrypted by XORing it with the output of
			invocations of the ChaCha20 function as needed, incrementing the
			first counter word after each block and overflowing into the second.
			The limits on the TLS plaintext size mean that the first counter word
			will never overflow in practice.
	4. Acknowledgements		The reason for generating the Poly1305 key like this rather than
			using key material from the handshake is that handshake key material
			is per-session, but for a polynomial MAC, a unique, secret key is
			needed per-record.
	The authors would like to thank Zooko Wilcox-OHearn and Samuel Neves		The Poly1305 key is used to calculate a tag for the following input:
	for suggestions that led to this draft.		the concatenation of the additional data, the number of bytes of
			additional data, the ciphertext and the number of bytes of
			ciphertext. Numbers are represented as 8-byte, little-endian values.
			The resulting tag is appended to the ciphertext, resulting in the
			output of the AEAD operation.
	5. IANA Considerations		Authenticated decryption is largely the reverse of the encryption
			process: generate one block of ChaCha20 keystream and use the first
			32 bytes as a Poly1305 key. Feed Poly1305 the additional data and
			ciphertext, with the length suffixing as described above. Verify, in
			constant time, that the calculated Poly1305 authenticator matches the
			final 16 bytes of the input. If not, the input can be rejected
			immediately. Otherwise, run ChaCha20, starting with a counter value
			of one, to decrypt the ciphertext.
	IANA is requested to allocate the following numbers in the TLS Cipher		When used in TLS, the "record_iv_length" is zero and the nonce is the
	Suite Registry (note that the third column contains the suggested		sequence number for the record, as an 8-byte, big-endian number. The
	ciphersuite numbers):		additional data is seq_num + TLSCompressed.type +
			TLSCompressed.version + TLSCompressed.length, where "+" denotes
			concatenation.
	TLS_RSA_WITH_CHACHA_SHA1 = {0xTBD, 0xTBD} {0xE5, 0x00}		In DTLS, the nonce is formed as the concatenation of the 16-bit epoch
	TLS_ECDHE_RSA_WITH_CHACHA_SHA1 = {0xTBD, 0xTBD} {0xE5, 0x01}		with the 48-bit sequence number.
	TLS_ECDHE_ECDSA_WITH_CHACHA_SHA1 = {0xTBD, 0xTBD} {0xE5, 0x02}
	TLS_PSK_WITH_CHACHA_SHA1 = {0xTBD, 0xTBD} {0xE5, 0x03}		In accordance with section 4 of RFC 5116 [RFC5116], the constants for
	TLS_ECDHE_PSK_WITH_CHACHA_SHA1 = {0xTBD, 0xTBD} {0xE5, 0x04}		this AEAD algorithm are as follows: K_LEN is 32 bytes, N_MIN and
	TLS_RSA_PSK_WITH_CHACHA_SHA1 = {0xTBD, 0xTBD} {0xE5, 0x05}		N_MAX are 8 bytes, P_MAX and A_MAX are 2^64, C_MAX is 2^64+16. An
			AEAD_CHACHA20_POLY1305 ciphertext is exactly 16 octets longer than
			its corresponding plaintext.
	TLS_DHE_PSK_WITH_CHACHA_SHA1 = {0xTBD, 0xTBD} {0xE5, 0x06}		Test vectors for this authenticator can be found in Appendix A.3.
	TLS_DHE_RSA_WITH_CHACHA_SHA1 = {0xTBD, 0xTBD} {0xE5, 0x07}
	6. Security Considerations		The following CipherSuites are defined.
	Chacha follows the same basic principle as Salsa20, a cipher with		TLS_RSA_WITH_CHACHA20_POLY1305 = {0xTBD, 0xTBD} {0xCC, 0x12}
			TLS_ECDHE_RSA_WITH_CHACHA20_POLY1305 = {0xTBD, 0xTBD} {0xCC, 0x13}
			TLS_ECDHE_ECDSA_WITH_CHACHA20_POLY1305 = {0xTBD, 0xTBD} {0xCC, 0x14}
			TLS_DHE_RSA_WITH_CHACHA20_POLY1305 = {0xTBD, 0xTBD} {0xCC, 0x15}
			TLS_DHE_PSK_WITH_CHACHA20_POLY1305 = {0xTBD, 0xTBD} {0xCC, 0x16}
			TLS_PSK_WITH_CHACHA20_POLY1305 = {0xTBD, 0xTBD} {0xCC, 0x17}
			TLS_ECDHE_PSK_WITH_CHACHA20_POLY1305 = {0xTBD, 0xTBD} {0xCC, 0x18}
			TLS_RSA_PSK_WITH_CHACHA20_POLY1305 = {0xTBD, 0xTBD} {0xCC, 0x19}
			5. Updates to the TLS Standard Stream Cipher
			The ChaCha20 ciphersuites with HMAC-SHA1 defined in this document
			differ from the TLS RC4 ciphersuites that have been the basis for the
			definition of Standard Stream Cipher. Unlike RC4, ChaCha20 requires
			a nonce per record. This however, does not affect the description of
			the Standard Stream Cipher if one assumes that a nonce is optional
			and depends on the cipher's characteristics.
			Hence, this document modifies the Standard Stream Cipher by adding an
			implicit nonce of 8-bytes, which is set to be the 64-bit TLS record
			sequence number. If the stream cipher needs more than 8 byte of
			nonce, it can obtain additional bytes for the implicit nonce from the
			client_write_iv and server_write_iv of the key_block.
			Stream ciphers that don't require a nonce such as RC4 shall ignore
			it. Other stream ciphers that require a nonce, such as ChaCha20 with
			HMAC-SHA1, will use the nonce and reset their state on each record.
			Note that in case of DTLS the 8-byte nonce is formed as the
			concatenation of the 16-bit epoch with the 48-bit sequence number,
			which are sent as part of the record.
			6. Updates to DTLS
			The DTLS protocol requires the cipher in use to introduce no
			dependencies between TLS Records to allow lost or rearranged records.
			For that it explicitly bans stream ciphers (see Section 3.1 of
			[RFC6347]).
			As the stream cipher described in this document, unlike RC4, does not
			require dependencies between records, this ban of stream ciphers is
			lifted with this document. Stream ciphers can be used with DTLS if
			they introduce no dependencies between records.
			7. Acknowledgements
			The authors would like to thank Zooko Wilcox-OHearn and Samuel Neves.
			8. IANA Considerations
			IANA is requested to assign a value for AEAD_CHACHA20_POLY1305 in the
			registry of AEAD algorithms [RFC5116], and also allocate the
			following Cipher Suites in the TLS Cipher Suite Registry (note that
			the third column contains the suggested ciphersuite numbers):
			TLS_RSA_WITH_CHACHA20_POLY1305 = {0xTBD, 0xTBD} {0xCC, 0x12}
			TLS_ECDHE_RSA_WITH_CHACHA20_POLY1305 = {0xTBD, 0xTBD} {0xCC, 0x13}
			TLS_ECDHE_ECDSA_WITH_CHACHA20_POLY1305 = {0xTBD, 0xTBD} {0xCC, 0x14}
			TLS_DHE_RSA_WITH_CHACHA20_POLY1305 = {0xTBD, 0xTBD} {0xCC, 0x15}
			TLS_DHE_PSK_WITH_CHACHA20_POLY1305 = {0xTBD, 0xTBD} {0xCC, 0x16}
			TLS_PSK_WITH_CHACHA20_POLY1305 = {0xTBD, 0xTBD} {0xCC, 0x17}
			TLS_ECDHE_PSK_WITH_CHACHA20_POLY1305 = {0xTBD, 0xTBD} {0xCC, 0x18}
			TLS_RSA_PSK_WITH_CHACHA20_POLY1305 = {0xTBD, 0xTBD} {0xCC, 0x19}
			TLS_RSA_WITH_CHACHA20_SHA = {0xTBD, 0xTBD} {0xCC, 0x20}
			TLS_ECDHE_RSA_WITH_CHACHA20_SHA = {0xTBD, 0xTBD} {0xCC, 0x21}
			TLS_ECDHE_ECDSA_WITH_CHACHA20_SHA = {0xTBD, 0xTBD} {0xCC, 0x22}
			TLS_DHE_RSA_WITH_CHACHA20_SHA = {0xTBD, 0xTBD} {0xCC, 0x23}
			TLS_DHE_PSK_WITH_CHACHA20_SHA = {0xTBD, 0xTBD} {0xCC, 0x24}
			TLS_PSK_WITH_CHACHA20_SHA = {0xTBD, 0xTBD} {0xCC, 0x25}
			TLS_ECDHE_PSK_WITH_CHACHA20_SHA = {0xTBD, 0xTBD} {0xCC, 0x26}
			TLS_RSA_PSK_WITH_CHACHA20_SHA = {0xTBD, 0xTBD} {0xCC, 0x27}
			9. Security Considerations
			ChaCha20 follows the same basic principle as Salsa20, a cipher with
	significant security review [SALSA20-SECURITY][ESTREAM]. At the time		significant security review [SALSA20-SECURITY][ESTREAM]. At the time
	of writing this document, there are no known significant security		of writing this document, there are no known significant security
	problems with either cipher, and Chacha is shown to be more resistant		problems with either cipher, and ChaCha20 is shown to be more
	in certain attacks than Salsa20 [SALSA20-ATTACK]. Furthermore Chacha		resistant in certain attacks than Salsa20 [SALSA20-ATTACK].
	was used as the core of the BLAKE hash function, a SHA3 finalist,		Furthermore ChaCha20 was used as the core of the BLAKE hash function,
	that had received considerable cryptanalytic attention [NIST-SHA3].		a SHA3 finalist, that had received considerable cryptanalytic
			attention [NIST-SHA3].
			Poly1305 is designed to ensure that forged messages are rejected with
			a probability of 1-(n/2^102) for a 16*n byte message, even after
			sending 2^64 legitimate messages.
			The cipher suites described in this document require that an nonce is
			never repeated under the same key. The design presented ensures that
			by using the TLS sequence number which is unique and does not wrap
			[RFC5246].
	This document should not introduce any other security considerations		This document should not introduce any other security considerations
	than those that directly follow from any use of the stream cipher		than those that directly follow from the use of the stream cipher
	Chacha and those that directly follow from introducing any set of		ChaCha20, the AEAD_CHACHA20_POLY1305 construction, and those that
	stream cipher suites into TLS and DTLS.		directly follow from introducing any set of stream cipher suites into
			TLS and DTLS.
	7. References		10. References
	7.1. Normative References		10.1. Normative References
	[RFC2246] Dierks, T. and C. Allen, "The TLS Protocol Version 1.0",		[RFC2246] Dierks, T. and C. Allen, "The TLS Protocol Version 1.0",
	RFC 2246, January 1999.		RFC 2246, January 1999.
	[RFC4346] Dierks, T. and E. Rescorla, "The Transport Layer Security		[RFC4346] Dierks, T. and E. Rescorla, "The Transport Layer Security
	(TLS) Protocol Version 1.1", RFC 4346, April 2006.		(TLS) Protocol Version 1.1", RFC 4346, April 2006.
	[RFC5246] Dierks, T. and E. Rescorla, "The Transport Layer Security
	(TLS) Protocol Version 1.2", RFC 5246, August 2008.
	[RFC4347] Rescorla, E. and N. Modadugu, "Datagram Transport Layer		[RFC4347] Rescorla, E. and N. Modadugu, "Datagram Transport Layer
	Security", RFC 4347, April 2006.		Security", RFC 4347, April 2006.
	[RFC4492] Blake-Wilson, S., Bolyard, N., Gupta, V., Hawk, C., and B.		[RFC4492] Blake-Wilson, S., Bolyard, N., Gupta, V., Hawk, C., and B.
	Moeller, "Elliptic Curve Cryptography (ECC) Cipher Suites		Moeller, "Elliptic Curve Cryptography (ECC) Cipher Suites
	for Transport Layer Security (TLS)", RFC 4492, May 2006.		for Transport Layer Security (TLS)", RFC 4492, May 2006.
			[RFC5116] McGrew, D., "An Interface and Algorithms for Authenticated
			Encryption", RFC 5116, January 2008.
			[RFC5246] Dierks, T. and E. Rescorla, "The Transport Layer Security
			(TLS) Protocol Version 1.2", RFC 5246, August 2008.
	[RFC5489] Badra, M. and I. Hajjeh, "ECDHE_PSK Cipher Suites for		[RFC5489] Badra, M. and I. Hajjeh, "ECDHE_PSK Cipher Suites for
	Transport Layer Security (TLS)", RFC 5489, March 2009.		Transport Layer Security (TLS)", RFC 5489, March 2009.
	[RFC6347] Rescorla, E. and N. Modadugu, "Datagram Transport Layer
	Security Version 1.2", RFC 6347, January 2012.
	[RFC6234] Eastlake, D. and T. Hansen, "US Secure Hash Algorithms		[RFC6234] Eastlake, D. and T. Hansen, "US Secure Hash Algorithms
	(SHA and SHA-based HMAC and HKDF)", RFC 6234, May 2011.		(SHA and SHA-based HMAC and HKDF)", RFC 6234, May 2011.
	[CHACHASPEC]		[RFC6347] Rescorla, E. and N. Modadugu, "Datagram Transport Layer
	Bernstein, D., "Chacha, a variant of Salsa20",		Security Version 1.2", RFC 6347, January 2012.
	WWW http://cr.yp.to/chacha/chacha-20080128.pdf,
	January 2008.
	7.2. Informative References		[CHACHA] Bernstein, D., "ChaCha, a variant of Salsa20",
			January 2008,
			<http://cr.yp.to/chacha/chacha-20080128.pdf>.
	[I-D.strombergson-chacha-test-vectors]		[POLY1305]
	Strombergson, J., "Test Vectors for the Stream Cipher		Bernstein, D., "The Poly1305-AES message-authentication
	ChaCha", draft-strombergson-chacha-test-vectors-00 (work		code.", March 2005,
	in progress), October 2013.		<http://cr.yp.to/mac/poly1305-20050329.pdf>.
			10.2. Informative References
	[SALSA20SPEC]		[SALSA20SPEC]
	Bernstein, D., "Salsa20 specification",		Bernstein, D., "Salsa20 specification", April 2005,
	WWW http://cr.yp.to/snuffle/spec.pdf, April 2005.		<http://cr.yp.to/snuffle/spec.pdf>.
	[RFC6101] Freier, A., Karlton, P., and P. Kocher, "The Secure		[RFC6101] Freier, A., Karlton, P., and P. Kocher, "The Secure
	Sockets Layer (SSL) Protocol Version 3.0", RFC 6101,		Sockets Layer (SSL) Protocol Version 3.0", RFC 6101,
	August 2011.		August 2011.
	[SALSA20-SECURITY]		[SALSA20-SECURITY]
	Bernstein, D., "Salsa20 security",		Bernstein, D., "Salsa20 security", April 2005,
	WWW http://cr.yp.to/snuffle/security.pdf, April 2005.		<http://cr.yp.to/snuffle/security.pdf>.
	[ESTREAM] Babbage, S., DeCanniere, C., Cantenaut, A., Cid, C.,		[ESTREAM] Babbage, S., DeCanniere, C., Cantenaut, A., Cid, C.,
	Gilbert, H., Johansson, T., Parker, M., Preneel, B.,		Gilbert, H., Johansson, T., Parker, M., Preneel, B.,
	Rijmen, V., and M. Robshaw, "The eSTREAM Portfolio (rev.		Rijmen, V., and M. Robshaw, "The eSTREAM Portfolio (rev.
	1)", WWW http://www.ecrypt.eu.org/stream/finallist.html,		1)", September 2008,
	September 2008.		<http://www.ecrypt.eu.org/stream/finallist.html>.
	[CBC-ATTACK]		[CBC-ATTACK]
	AlFardan, N. and K. Paterson, "Lucky Thirteen: Breaking		AlFardan, N. and K. Paterson, "Lucky Thirteen: Breaking
	the TLS and DTLS Record Protocols", IEEE Symposium on		the TLS and DTLS Record Protocols", IEEE Symposium on
	Security and Privacy , 2013.		Security and Privacy , 2013.
	[RC4-ATTACK]		[RC4-ATTACK]
	Isobe, T., Ohigashi, T., Watanabe, Y., and M. Morii, "Full		Isobe, T., Ohigashi, T., Watanabe, Y., and M. Morii, "Full
	Plaintext Recovery Attack on Broadcast RC4", International		Plaintext Recovery Attack on Broadcast RC4", International
	Workshop on Fast Software Encryption , 2013.		Workshop on Fast Software Encryption , 2013.
	[AEAD-PERFORMANCE]
	Krovetz, T. and P. Rogaway, "The Software Performance of
	Authenticated-Encryption Modes", International Workshop on
	Fast Software Encryption , 2011.
	[SALSA20-ATTACK]		[SALSA20-ATTACK]
	Aumasson, J-P., Fischer, S., Khazaei, S., Meier, W., and		Aumasson, J-P., Fischer, S., Khazaei, S., Meier, W., and
	C. Rechberger, "New Features of Latin Dances: Analysis of		C. Rechberger, "New Features of Latin Dances: Analysis of
	Salsa, ChaCha, and Rumba",		Salsa, ChaCha, and Rumba", 2007,
	WWW http://eprint.iacr.org/2007/472.pdf, 2007.		<http://eprint.iacr.org/2007/472.pdf>.
	[VLSI-IMPL]		[NACLCRYPTO]
	Henzen, L., Carbognani, F., and W. Fichtner, "VLSI		Bernstein, D., "Cryptography in NaCl", March 2009,
	hardware evaluation of the stream ciphers Salsa20 and		<http://cr.yp.to/highspeed/naclcrypto-20090310.pdf>.
	ChaCha, and the compression function Rumba", 2008.
	[NIST-SHA3]		[NIST-SHA3]
	Chang, S., Burr, W., Kelsey, J., Paul, S., and L. Bassham,		Chang, S., Burr, W., Kelsey, J., Paul, S., and L. Bassham,
	"Third-Round Report of the SHA-3 Cryptographic Hash		"Third-Round Report of the SHA-3 Cryptographic Hash
	Algorithm Competition",		Algorithm Competition", 2012,
	WWW http://dx.doi.org/10.6028/NIST.IR.7896, 2012.		<http://dx.doi.org/10.6028/NIST.IR.7896>.
			Appendix A. Test vectors
			A.1. ChaCha20
			The following blocks contain test vectors for ChaCha20. The first
			line contains the 256-bit key, the second the 64-bit nonce and the
			last line contains a prefix of the resulting ChaCha20 key-stream.
			KEY: 00000000000000000000000000000000000000000000000000000000
			00000000
			NONCE: 0000000000000000
			KEYSTREAM: 76b8e0ada0f13d90405d6ae55386bd28bdd219b8a08ded1aa836efcc
			8b770dc7da41597c5157488d7724e03fb8d84a376a43b8f41518a11c
			c387b669b2ee6586
			KEY: 00000000000000000000000000000000000000000000000000000000
			00000001
			NONCE: 0000000000000000
			KEYSTREAM: 4540f05a9f1fb296d7736e7b208e3c96eb4fe1834688d2604f450952
			ed432d41bbe2a0b6ea7566d2a5d1e7e20d42af2c53d792b1c43fea81
			7e9ad275ae546963
			KEY: 00000000000000000000000000000000000000000000000000000000
			00000000
			NONCE: 0000000000000001
			KEYSTREAM: de9cba7bf3d69ef5e786dc63973f653a0b49e015adbff7134fcb7df1
			37821031e85a050278a7084527214f73efc7fa5b5277062eb7a0433e
			445f41e3
			KEY: 00000000000000000000000000000000000000000000000000000000
			00000000
			NONCE: 0100000000000000
			KEYSTREAM: ef3fdfd6c61578fbf5cf35bd3dd33b8009631634d21e42ac33960bd1
			38e50d32111e4caf237ee53ca8ad6426194a88545ddc497a0b466e7d
			6bbdb0041b2f586b
			KEY: 000102030405060708090a0b0c0d0e0f101112131415161718191a1b
			1c1d1e1f
			NONCE: 0001020304050607
			KEYSTREAM: f798a189f195e66982105ffb640bb7757f579da31602fc93ec01ac56
			f85ac3c134a4547b733b46413042c9440049176905d3be59ea1c53f1
			5916155c2be8241a38008b9a26bc35941e2444177c8ade6689de9526
			4986d95889fb60e84629c9bd9a5acb1cc118be563eb9b3a4a472f82e
			09a7e778492b562ef7130e88dfe031c79db9d4f7c7a899151b9a4750
			32b63fc385245fe054e3dd5a97a5f576fe064025d3ce042c566ab2c5
			07b138db853e3d6959660996546cc9c4a6eafdc777c040d70eaf46f7
			6dad3979e5c5360c3317166a1c894c94a371876a94df7628fe4eaaf2
			ccb27d5aaae0ad7ad0f9d4b6ad3b54098746d4524d38407a6deb3ab7
			8fab78c9
			A.2. Poly1305
			The following blocks contain test vectors for Poly1305. The first
			line contains a variable length input. The second contains the 256-
			bit key and the last contains the resulting, 128-bit tag.
			INPUT: 000000000000000000000000000000000000000000000000000000000000
			0000
			KEY: 746869732069732033322d62797465206b657920666f7220506f6c793133
			3035
			TAG: 49ec78090e481ec6c26b33b91ccc0307
			INPUT: 48656c6c6f20776f726c6421
			KEY: 746869732069732033322d62797465206b657920666f7220506f6c793133
			3035
			TAG: a6f745008f81c916a20dcc74eef2b2f0
			A.3. AEAD_CHACHA20_POLY1305
			The following block contains a test vector for the
			AEAD_CHACHA20_POLY1305 algorithm. The first four lines consist of
			the standard inputs to an AEAD algorithm and the last line contains
			the encrypted and authenticated result.
			KEY: 4290bcb154173531f314af57f3be3b5006da371ece272afa1b5dbdd110
			0a1007
			INPUT: 86d09974840bded2a5ca
			NONCE: cd7cf67be39c794a
			AD: 87e229d4500845a079c0
			OUTPUT: e3e446f7ede9a19b62a4677dabf4e3d24b876bb284753896e1d6
			To aid implementations, the next block contains some intermediate
			values in the AEAD_CHACHA20_POLY1305 algorithm. The first line
			contains the Poly1305 key that is derived and the second contains the
			raw bytes that are authenticated by Poly1305.
			KEY: 9052a6335505b6d507341169783dccac0e26f84ea84906b1558c05bf4815
			0fbe
			INPUT: 87e229d4500845a079c00a00000000000000e3e446f7ede9a19b62a40a00
			000000000000
	Authors' Addresses		Authors' Addresses
			Adam Langley
			Google Inc
			Email: agl@google.com
			Wan-Teh Chang
			Google Inc
			Email: wtc@google.com
	Nikos Mavrogiannopoulos		Nikos Mavrogiannopoulos
	Red Hat		Red Hat
	Email: nmav@redhat.com		Email: nmav@redhat.com
	Joachim Strombergson		Joachim Strombergson
	Secworks Sweden AB		Secworks Sweden AB
	Email: joachim@secworks.se		Email: joachim@secworks.se
	URI: http://secworks.se/		URI: http://secworks.se/
End of changes. 51 change blocks.
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