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: [email protected]


  Jaeho Yoon
  Korea Information Security Agency

  Phone: +82-2-405-5434
  Fax  : +82-2-405-5219
  EMail: [email protected]


  Jaeil Lee
  Korea Information Security Agency

  Phone: +82-2-405-5300
  Fax  : +82-2-405-5219
  EMail: [email protected]



























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Full Copyright Statement

  Copyright (C) The Internet Society (2005).

  This document is subject to the rights, licenses and restrictions
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  retain all their rights.

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Acknowledgement

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  Internet Society.







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