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diff --git a/doc/protocol/draft-ietf-tls-ecc-new-mac-04.txt b/doc/protocol/draft-ietf-tls-ecc-new-mac-04.txt deleted file mode 100644 index ebcf7fc3e6..0000000000 --- a/doc/protocol/draft-ietf-tls-ecc-new-mac-04.txt +++ /dev/null @@ -1,448 +0,0 @@ - - - -Network Working Group E. Rescorla -Internet-Draft RTFM, Inc. -Intended status: Informational February 12, 2008 -Expires: August 15, 2008 - - -TLS Elliptic Curve Cipher Suites with SHA-256/384 and AES Galois Counter - Mode - draft-ietf-tls-ecc-new-mac-04.txt - -Status of this Memo - - By submitting this Internet-Draft, each author represents that any - applicable patent or other IPR claims of which he or she is aware - have been or will be disclosed, and any of which he or she becomes - aware will be disclosed, in accordance with Section 6 of BCP 79. - - Internet-Drafts are working documents of the Internet Engineering - Task Force (IETF), its areas, and its working groups. Note that - other groups may also distribute working documents as Internet- - Drafts. - - Internet-Drafts are draft documents valid for a maximum of six months - and may be updated, replaced, or obsoleted by other documents at any - time. It is inappropriate to use Internet-Drafts as reference - material or to cite them other than as "work in progress." - - The list of current Internet-Drafts can be accessed at - http://www.ietf.org/ietf/1id-abstracts.txt. - - The list of Internet-Draft Shadow Directories can be accessed at - http://www.ietf.org/shadow.html. - - This Internet-Draft will expire on August 15, 2008. - -Copyright Notice - - Copyright (C) The IETF Trust (2008). - -Abstract - - RFC 4492 describes elliptic curve cipher suites for Transport Layer - Security (TLS). However, all those cipher suites use SHA-1 as their - MAC algorithm. This document describes eight new CipherSuites for - TLS/DTLS which specify stronger digest algorithms. Four use HMAC - with SHA-256 or SHA-384 and four use AES in Galois Counter Mode - (GCM). - - - - -Rescorla Expires August 15, 2008 [Page 1] - -Internet-Draft TLS ECC New MAC February 2008 - - -Table of Contents - - 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 - 1.1. Conventions Used In This Document . . . . . . . . . . . . . 3 - 2. Cipher Suites . . . . . . . . . . . . . . . . . . . . . . . . . 3 - 2.1. HMAC-based Cipher Suites . . . . . . . . . . . . . . . . . 3 - 2.2. Galois Counter Mode-based Cipher Suites . . . . . . . . . . 4 - 3. TLS Versions . . . . . . . . . . . . . . . . . . . . . . . . . 5 - 4. Security Considerations . . . . . . . . . . . . . . . . . . . . 5 - 4.1. Downgrade Attack . . . . . . . . . . . . . . . . . . . . . 5 - 4.2. Perfect Forward Secrecy . . . . . . . . . . . . . . . . . . 5 - 4.3. Counter Reuse with GCM . . . . . . . . . . . . . . . . . . 6 - 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 6 - 6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 6 - 7. References . . . . . . . . . . . . . . . . . . . . . . . . . . 6 - 7.1. Normative References . . . . . . . . . . . . . . . . . . . 6 - 7.2. Informative References . . . . . . . . . . . . . . . . . . 7 - Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 7 - Intellectual Property and Copyright Statements . . . . . . . . . . 8 - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -Rescorla Expires August 15, 2008 [Page 2] - -Internet-Draft TLS ECC New MAC February 2008 - - -1. Introduction - - RFC 4492 [RFC4492] describes Elliptic Curve Cryptography (ECC) cipher - suites for Transport Layer Security (TLS). However, all of the RFC - 4492 suites use HMAC-SHA1 as their MAC algorithm. Due to recent - analytic work on SHA-1 [Wang05], the IETF is gradually moving away - from SHA-1 and towards stronger hash algorithms. This document - specifies TLS ECC cipher suites which replace SHA-256 and SHA-384 - rather than SHA-1. - - TLS 1.2 [I-D.ietf-tls-rfc4346-bis], adds support for authenticated - encryption with additional data (AEAD) cipher modes - [I-D.mcgrew-auth-enc]. This document also specifies a set of ECC - cipher suites using one such mode, Galois Counter Mode (GCM) [GCM]. - Another document [I-D.salowey-tls-rsa-aes-gcm], provides support for - GCM with other key establishment methods. - -1.1. Conventions Used In This Document - - The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", - "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this - document are to be interpreted as described in [RFC2119]. - - -2. Cipher Suites - - This document defines 8 new cipher suites to be added to TLS. All - use Elliptic Curve Cryptography for key exchange and digital - signature, as defined in RFC 4492. - -2.1. HMAC-based Cipher Suites - - The first four cipher suites use AES [AES] in CBC [CBC] mode with an - HMAC-based MAC: - - CipherSuite TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA256 = {0xXX,XX}; - CipherSuite TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA384 = {0xXX,XX}; - CipherSuite TLS_ECDH_ECDSA_WITH_AES_128_CBC_SHA256 = {0xXX,XX}; - CipherSuite TLS_ECDH_ECDSA_WITH_AES_256_CBC_SHA384 = {0xXX,XX}; - - These four cipher suites are the same as the corresponding cipher - suites in RFC 4492 (TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA, - TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA, - TLS_ECDH_ECDSA_WITH_AES_128_CBC_SHA, and - TLS_ECDH_ECDSA_WITH_AES_256_CBC_SHA) except for the hash and PRF - algorithms, which are SHA-256 and SHA-384 [SHS] as follows. - - - - - -Rescorla Expires August 15, 2008 [Page 3] - -Internet-Draft TLS ECC New MAC February 2008 - - - Cipher Suite MAC PRF - ------------ --- --- - TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA256 HMAC-SHA-256 P_SHA-256 - TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA384 HMAC-SHA-384 P_SHA-384 - TLS_ECDH_ECDSA_WITH_AES_128_CBC_SHA256 HMAC-SHA-256 P_SHA-256 - TLS_ECDH_ECDSA_WITH_AES_256_CBC_SHA384 HMAC-SHA-384 P_SHA-384 - -2.2. Galois Counter Mode-based Cipher Suites - - The second four cipher suites use the new authenticated encryption - modes defined in TLS 1.2 with AES in Galois Counter Mode (GCM) [GCM]: - - CipherSuite TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256 = {0xXX,XX}; - CipherSuite TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384 = {0xXX,XX}; - CipherSuite TLS_ECDH_ECDSA_WITH_AES_128_GCM_SHA256 = {0xXX,XX}; - CipherSuite TLS_ECDH_ECDSA_WITH_AES_256_GCM_SHA384 = {0xXX,XX}; - - These cipher suites use authenticated encryption with additional data - algorithms AEAD_AES_128_GCM and AEAD_AES_256_GCM described in - [I-D.mcgrew-auth-enc]. The "nonce" input to the AEAD algorithm SHALL - be 12 bytes long, and is "partially implicit" (see Section 3.2.1 of - [I-D.mcgrew-auth-enc]). Part of the nonce is generated as part of - the handshake process and is static for the entire session and part - is carried in each packet. - - struct { - opaque salt[4]; - opaque explicit_nonce_part[8]; - } GCMNonce. - - The salt value is either the client_write_IV if the client is sending - or the server_write_IV if the server is sending. These IVs SHALL be - 4 bytes long. Therefore, for all the algorithms defined in this - section, SecurityParameters.fixed_iv_length=4. - - The explicit_nonce_part is chosen by the sender and included in the - packet. Each value of the explicit_nonce_part MUST be distinct from - all other values, for any fixed key. Failure to meet this uniqueness - requirement can significantly degrade security. The - explicit_nonce_part is carried in the IV field of the - GenericAEADCipher structure. Therefore, for all the algorithms - defined in this section, SecurityParameters.record_iv_length=8. - - In the case of TLS the counter MAY be the 64-bit sequence number. In - the case of Datagram TLS [RFC4347] the counter MAY be formed from the - concatenation of the 16-bit epoch with the 48-bit sequence number. - - The PRF algorithms SHALL be as follows: - - - -Rescorla Expires August 15, 2008 [Page 4] - -Internet-Draft TLS ECC New MAC February 2008 - - - For TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256 and - TLS_ECDH_ECDSA_WITH_AES_128_GCM_SHA256 it SHALL be P_SHA-256. - - For TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA384 and - TLS_ECDH_ECDSA_WITH_AES_128_GCM_SHA384 it SHALL be P_SHA-384. - - -3. TLS Versions - - Because these cipher suites depend on features available only in TLS - 1.2 (PRF flexibility and combined authenticated encryption cipher - modes), they MUST NOT be negotiated by older versions of TLS. - Clients MUST NOT offer these cipher suites if they do not offer TLS - 1.2 or later. Servers which select an earlier version of TLS MUST - NOT select one of these cipher suites. Because TLS has no way for - the client to indicate that it supports TLS 1.2 but not earlier, a - non-compliant server might potentially negotiate TLS 1.1 or earlier - and select one of the cipher suites in this document. Clients MUST - check the TLS version and generate a fatal "illegal_parameter" alert - if they detect an incorrect version. - - -4. Security Considerations - - The security considerations in RFC 4346 and RFC 4492 apply to this - document as well. The remainder of this section describes security - considerations specific to the cipher suites described in this - document. - -4.1. Downgrade Attack - - TLS negotiation is only as secure as the weakest cipher suite that is - supported. For instance, an implementation which supports both 160- - bit and 256-bit elliptic curves can be subject to an active downgrade - attack to the 160-bit security level. An attacker who can attack - that can then forge the Finished handshake check and successfully - mount a man-in-the-middle attack. - -4.2. Perfect Forward Secrecy - - The static ECDH cipher suites specified in this document do not - provide perfect forward secrecy (PFS). Thus, compromise of a single - static key leads to potential decryption of all traffic protected - using that key. Implementors of this specification SHOULD provide at - least one ECDHE mode of operation. - - - - - - -Rescorla Expires August 15, 2008 [Page 5] - -Internet-Draft TLS ECC New MAC February 2008 - - -4.3. Counter Reuse with GCM - - AES-GCM is only secure if the counter is never reused. The IV - construction algorithm above is designed to ensure that this cannot - happen. - - -5. IANA Considerations - - IANA has assigned the following values for these cipher suites: - - CipherSuite TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA256 = {0xXX,XX}; - CipherSuite TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA384 = {0xXX,XX}; - CipherSuite TLS_ECDH_ECDSA_WITH_AES_128_CBC_SHA256 = {0xXX,XX}; - CipherSuite TLS_ECDH_ECDSA_WITH_AES_256_CBC_SHA384 = {0xXX,XX}; - CipherSuite TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256 = {0xXX,XX}; - CipherSuite TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384 = {0xXX,XX}; - CipherSuite TLS_ECDH_ECDSA_WITH_AES_128_GCM_SHA256 = {0xXX,XX}; - CipherSuite TLS_ECDH_ECDSA_WITH_AES_256_GCM_SHA384 = {0xXX,XX}; - - -6. Acknowledgements - - This work was supported by the US Department of Defense. - - David McGrew contributed substantual sections of the GCM nonce text - as well as providing a review of this document. - - -7. References - -7.1. Normative References - - [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate - Requirement Levels", BCP 14, RFC 2119, March 1997. - - [RFC4492] Blake-Wilson, S., Bolyard, N., Gupta, V., Hawk, C., and B. - Moeller, "Elliptic Curve Cryptography (ECC) Cipher Suites - for Transport Layer Security (TLS)", RFC 4492, May 2006. - - [I-D.mcgrew-auth-enc] - McGrew, D., "An Interface and Algorithms for Authenticated - Encryption", draft-mcgrew-auth-enc-05 (work in progress), - November 2007. - - [I-D.ietf-tls-rfc4346-bis] - Dierks, T. and E. Rescorla, "The Transport Layer Security - (TLS) Protocol Version 1.2", draft-ietf-tls-rfc4346-bis-09 - - - -Rescorla Expires August 15, 2008 [Page 6] - -Internet-Draft TLS ECC New MAC February 2008 - - - (work in progress), February 2008. - - [AES] National Institute of Standards and Technology, - "Specification for the Advanced Encryption Standard - (AES)", FIPS 197, November 2001. - - [SHS] National Institute of Standards and Technology, "Secure - Hash Standard", FIPS 180-2, August 2002. - - [CBC] National Institute of Standards and Technology, - "Recommendation for Block Cipher Modes of Operation - - Methods and Techniques", SP 800-38A, December 2001. - - [GCM] National Institute of Standards and Technology, - "Recommendation for Block Cipher Modes of Operation: - Galois;/Counter Mode (GCM) for Confidentiality and - Authentication", SP 800-38D, November 2007. - -7.2. Informative References - - [Wang05] Wang, X., Yin, Y., and H. Yu, "Finding Collisions in the - Full SHA-1", CRYPTO 2005, August 2005. - - [RFC4347] Rescorla, E. and N. Modadugu, "Datagram Transport Layer - Security", RFC 4347, April 2006. - - [I-D.salowey-tls-rsa-aes-gcm] - Salowey, J., "RSA based AES-GCM Cipher Suites for TLS", - draft-salowey-tls-rsa-aes-gcm-00 (work in progress), - February 2007. - - -Author's Address - - Eric Rescorla - RTFM, Inc. - 2064 Edgewood Drive - Palo Alto 94303 - USA - - Email: ekr@rtfm.com - - - - - - - - - - -Rescorla Expires August 15, 2008 [Page 7] - -Internet-Draft TLS ECC New MAC February 2008 - - -Full Copyright Statement - - Copyright (C) The IETF Trust (2008). - - This document is subject to the rights, licenses and restrictions - contained in BCP 78, and except as set forth therein, the authors - retain all their rights. - - This document and the information contained herein are provided on an - "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS - OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY, THE IETF TRUST AND - THE INTERNET ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS - OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF - THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED - WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. - - -Intellectual Property - - The IETF takes no position regarding the validity or scope of any - Intellectual Property Rights or other rights that might be claimed to - pertain to the implementation or use of the technology described in - this document or the extent to which any license under such rights - might or might not be available; nor does it represent that it has - made any independent effort to identify any such rights. Information - on the procedures with respect to rights in RFC documents can be - found in BCP 78 and BCP 79. - - Copies of IPR disclosures made to the IETF Secretariat and any - assurances of licenses to be made available, or the result of an - attempt made to obtain a general license or permission for the use of - such proprietary rights by implementers or users of this - specification can be obtained from the IETF on-line IPR repository at - http://www.ietf.org/ipr. - - The IETF invites any interested party to bring to its attention any - copyrights, patents or patent applications, or other proprietary - rights that may cover technology that may be required to implement - this standard. Please address the information to the IETF at - ietf-ipr@ietf.org. - - -Acknowledgment - - Funding for the RFC Editor function is provided by the IETF - Administrative Support Activity (IASA). - - - - - -Rescorla Expires August 15, 2008 [Page 8] - |