





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.









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   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,
   http://www.kisa.or.kr/seed/seed_eng.html, 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].





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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].















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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)
                http://www.tta.or.kr/English/new/main/index.htm.

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,
                http://www.kisa.or.kr/seed/seed_eng.html.

   [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
                (n2656_3.zip), October 2000.

   [SEED-EVAL]  KISA, "Self Evaluation Report",
                http://www.kisa.or.kr/seed/seed_eng.html.

   [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.








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Authors' Addresses

   Hyangjin Lee
   Korea Information Security Agency

   Phone: +82-2-405-5446
   Fax  : +82-2-405-5319
   EMail: jiinii@kisa.or.kr


   Jaeho Yoon
   Korea Information Security Agency

   Phone: +82-2-405-5434
   Fax  : +82-2-405-5219
   EMail: jhyoon@kisa.or.kr


   Jaeil Lee
   Korea Information Security Agency

   Phone: +82-2-405-5300
   Fax  : +82-2-405-5219
   EMail: jilee@kisa.or.kr



























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Acknowledgement

   Funding for the RFC Editor function is currently provided by the
   Internet Society.







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