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Addition of SEED Cipher Suites to Transport Layer Security (TLS).
H.J. Lee, J.H. Yoon, J.I. Lee. August 2005.

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Network Working Group H.J. Lee Request for Comments: 4162 J.H. Yoon Category: Standards Track J.I. Lee KISA August 2005 Addition of SEED Cipher Suites to Transport Layer Security (TLS) Status of This Memo This document specifies an Internet standards track protocol for the Internet community, and requests discussion and suggestions for improvements. Please refer to the current edition of the "Internet Official Protocol Standards" (STD 1) for the standardization state and status of this protocol. Distribution of this memo is unlimited. Copyright Notice Copyright (C) The Internet Society (2005). Abstract This document proposes the addition of new cipher suites to the Transport Layer Security (TLS) protocol to support the SEED encryption algorithm as a bulk cipher algorithm. 1. Introduction This document proposes the addition of new cipher suites to the TLS protocol [TLS] to support the SEED encryption algorithm as a bulk cipher algorithm. 1.1. SEED SEED is a symmetric encryption algorithm that was developed by Korea Information Security Agency (KISA) and a group of experts, beginning in 1998. The input/output block size of SEED is 128-bit and the key length is also 128-bit. SEED has the 16-round Feistel structure. A 128-bit input is divided into two 64-bit blocks and the right 64-bit block is an input to the round function with a 64-bit subkey generated from the key scheduling. Lee, et al. Standards Track [Page 1]
RFC 4162 SEED Cipher Suites to TLS August 2005 SEED is easily implemented in various software and hardware because it is designed to increase the efficiency of memory storage and the simplicity of generating keys without degrading the security of the algorithm. In particular, it can be effectively adopted in a computing environment that has a restricted resources such as mobile devices, smart cards, and so on. SEED is a national industrial association standard [TTASSEED] and is widely used in South Korea for electronic commerce and financial services operated on wired & wireless PKI. The algorithm specification and object identifiers are described in [SEED-ALG]. The SEED homepage,, contains a wealth of information about SEED, including detailed specification, evaluation report, test vectors, and so on. 1.2. Terminology The key words "MUST", "MUST NOT", "REQUIRED", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document (in uppercase, as shown) are to be interpreted as described in [RFC2119]. 2. Proposed Cipher Suites The new cipher suites proposed here have the following definitions: CipherSuite TLS_RSA_WITH_SEED_CBC_SHA = { 0x00, 0x96}; CipherSuite TLS_DH_DSS_WITH_SEED_CBC_SHA = { 0x00, 0x97}; CipherSuite TLS_DH_RSA_WITH_SEED_CBC_SHA = { 0x00, 0x98}; CipherSuite TLS_DHE_DSS_WITH_SEED_CBC_SHA = { 0x00, 0x99}; CipherSuite TLS_DHE_RSA_WITH_SEED_CBC_SHA = { 0x00, 0x9A}; CipherSuite TLS_DH_anon_WITH_SEED_CBC_SHA = { 0x00, 0x9B}; 3. Cipher Suite Definitions 3.1. Cipher All the cipher suites described here use SEED in cipher block chaining (CBC) mode as a bulk cipher algorithm. SEED is a 128-bit block cipher with 128-bit key size. 3.2. Hash All the cipher suites described here use SHA-1 [SHA-1] in an HMAC construction as described in section 5 of [TLS]. Lee, et al. Standards Track [Page 2]
RFC 4162 SEED Cipher Suites to TLS August 2005 3.3. Key Exchange The cipher suites defined here differ in the type of certificate and key exchange method. They use the following options: CipherSuite Key Exchange Algorithm TLS_RSA_WITH_SEED_CBC_SHA RSA TLS_DH_DSS_WITH_SEED_CBC_SHA DH_DSS TLS_DH_RSA_WITH_SEED_CBC_SHA DH_RSA TLS_DHE_DSS_WITH_SEED_CBC_SHA DHE_DSS TLS_DHE_RSA_WITH_SEED_CBC_SHA DHE_RSA TLS_DH_anon_WITH_SEED_CBC_SHA DH_anon For the meanings of the terms RSA, DH_DSS, DH_RSA, DHE_DSS, DHE_RSA, and DH_anon, please refer to sections 7.4.2 and 7.4.3 of [TLS]. 4. Security Considerations It is not believed that the new cipher suites are less secure than the corresponding older ones. No security problem has been found on SEED. SEED is robust against known attacks, including differential cryptanalysis, linear cryptanalysis, and related key attacks, etc. SEED has gone through wide public scrutinizing procedures. Especially, it has been evaluated and also considered cryptographically secure by trustworthy organizations such as ISO/IEC JTC 1/SC 27 and Japan CRYPTREC (Cryptography Research and Evaluation Committees) [ISOSEED] [CRYPTREC]. SEED has been submitted to several other standardization bodies such as ISO (ISO/IEC 18033-3) and IETF S/MIME Mail Security [SEED-SMIME]; and it is under consideration. For further security considerations, the reader is encouraged to read [SEED-EVAL]. For other security considerations, please refer to the security of the corresponding older cipher suites described in [TLS] and [AES-TLS]. Lee, et al. Standards Track [Page 3]
RFC 4162 SEED Cipher Suites to TLS August 2005 5. References 5.1. Normative References [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [TLS] Dierks, T. and C. Allen, "The TLS Protocol Version 1.0", RFC 2246, January 1999. [TTASSEED] Telecommunications Technology Association (TTA), South Korea, "128-bit Symmetric Block Cipher (SEED)", TTAS.KO-12.0004, September 1998, (In Korean) 5.2. Informative References [AES-TLS] Chown, P., "Advanced Encryption Standard (AES) Ciphersuites for Transport Layer Security (TLS)", RFC 3268, June 2002. [CRYPTREC] Information-technology Promotion Agency (IPA), Japan, CRYPTREC. "SEED Evaluation Report", February 2002, [ISOSEED] ISO/IEC JTC 1/SC 27, "National Body contributions on NP 18033 'Encryption Algorithms' in Response to SC 27 N2563 (ATT.3 Korea Contribution)", ISO/IEC JTC 1/SC 27 N2656r1 (, October 2000. [SEED-EVAL] KISA, "Self Evaluation Report", [SEED-ALG] Park, J., Lee, S., Kim, J., and J. Lee, "The SEED Encryption Algorithm", RFC 4009, February 2005. [SEED-SMIME] Park, J., Lee, S., Kim, J., and J. Lee, "Use of the SEED Encryption Algorithm in Cryptographic Message Syntax (CMS)", RFC 4010, February 2005. [SHA-1] FIPS PUB 180-1, "Secure Hash Standard", National Institute of Standards and Technology, U.S. Department of Commerce, April 17, 1995. Lee, et al. Standards Track [Page 4]
RFC 4162 SEED Cipher Suites to TLS August 2005 Authors' Addresses Hyangjin Lee Korea Information Security Agency Phone: +82-2-405-5446 Fax : +82-2-405-5319 EMail: Jaeho Yoon Korea Information Security Agency Phone: +82-2-405-5434 Fax : +82-2-405-5219 EMail: Jaeil Lee Korea Information Security Agency Phone: +82-2-405-5300 Fax : +82-2-405-5219 EMail: Lee, et al. Standards Track [Page 5]
RFC 4162 SEED Cipher Suites to TLS August 2005 Full Copyright Statement Copyright (C) The Internet Society (2005). 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 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 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- Acknowledgement Funding for the RFC Editor function is currently provided by the Internet Society. Lee, et al. Standards Track [Page 6]


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