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Network Working Group                                            A. KatoRequest for Comments: 4312                      NTT Software CorporationCategory: Standards Track                                      S. Moriai                                        Sony Computer Entertainment Inc.                                                                M. Kanda                              Nippon Telegraph and Telephone Corporation                                                           December 2005The Camellia Cipher Algorithm and Its Use With IPsecStatus 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 describes the use of the Camellia block cipher   algorithm in Cipher Block Chaining Mode, with an explicit   Initialization Vector, as a confidentiality mechanism within the   context of the IPsec Encapsulating Security Payload (ESP).1.  Introduction   This document describes the use of the Camellia block cipher   algorithm in Cipher Block Chaining Mode, with an explicit   Initialization Vector, as a confidentiality mechanism within the   context of the IPsec Encapsulating Security Payload (ESP).   Camellia was selected as a recommended cryptographic primitive by the   EU NESSIE (New European Schemes for Signatures, Integrity and   Encryption) project [NESSIE] and was included in the list of   cryptographic techniques for Japanese e-Government systems that was   selected by the Japan CRYPTREC (Cryptography Research, Evaluation   Committees) [CRYPTREC].  Camellia has been submitted to several other   standardization bodies, such as ISO (ISO/IEC 18033) and the IETF   S/MIME Mail Security Working Group [Camellia-CMS].Kato, et al.                Standards Track                     [Page 1]

RFC 4312                    Camellia Cipher                December 2005   Camellia supports 128-bit block size and 128-, 192-, and 256-bit key   lengths, i.e., the same interface specifications as the Advanced   Encryption Standard (AES) [AES].   Camellia is a symmetric cipher with a Feistel structure.  Camillia   was developed jointly by NTT and Mitsubishi Electric Corporation in   2000.  It was designed to withstand all known cryptanalytic attacks,   and it has been scrutinized by worldwide cryptographic experts.   Camellia is suitable for implementation in software and hardware,   offering encryption speed in software and hardware implementations   that is comparable to AES.   The Camellia homepage [Camellia-Web] contains a wealth of information   about camellia, including detailed specification, security analysis,   performance figures, reference implementation, test vectors, and   intellectual property information.   The remainder of this document specifies the use of Camellia within   the context of IPsec ESP.  For further information on how the various   pieces of ESP fit together to provide security services, please refer   to [ARCH], [ESP], and [ROAD].1.1.  Specification of Requirements   The keywords "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" that   appear in this document are to be interpreted as described in   [RFC-2119].2.  The Camellia Cipher Algorithm   All symmetric block cipher algorithms share common characteristics   and variables, including mode, key size, weak keys, block size, and   rounds.  The following sections contain descriptions of the relevant   characteristics of Camellia.   The algorithm specification and object identifiers are described in   [Camellia-Desc].2.1.  Mode   NIST has defined five modes of operation for AES and other FIPS-   approved ciphers [SP800-38a]: CBC (Cipher Block Chaining), ECB   (Electronic CodeBook), CFB (Cipher FeedBack), OFB (Output FeedBack),   and CTR (Counter).  The CBC mode is well defined and well understood   for symmetric ciphers, and it is currently required for all other ESP   ciphers.  This document specifies the use of the Camellia cipher in   CBC mode within ESP.  This mode requires an Initialization VectorKato, et al.                Standards Track                     [Page 2]

RFC 4312                    Camellia Cipher                December 2005   (IV) size that is the same as the block size.  Use of a randomly   generated IV prevents generation of identical cipher text from   packets that have identical data spanning the first block of the   cipher algorithm's block size.   The CBC IV is XOR'd with the first plaintext block before it is   encrypted.  Then, for successive blocks, the previous cipher text   block is XOR'd with the current plain text before it is encrypted.   More information on CBC mode can be obtained in [SP800-38a,   CRYPTO-S].2.2.  Key Size   Camellia supports three key sizes: 128 bits, 192 bits, and 256 bits.   The default key size is 128 bits, and all implementations MUST   support this key size.  Implementations MAY also support key sizes of   192 bits and 256 bits.   Camellia uses a different number of rounds for each of the defined   key sizes.  When a 128-bit key is used, implementations MUST use 18   rounds.  When a 192-bit key is used, implementations MUST use 24   rounds.  When a 256-bit key is used, implementations MUST use 24   rounds.2.3.  Weak Keys   At the time of writing this document, there are no known weak keys   for Camellia.2.4.  Block Size and Padding   Camellia uses a block size of sixteen octets (128 bits).   Padding is required by the algorithms to maintain a 16-octet   (128-bit) block size.  Padding MUST be added, as specified in [ESP],   such that the data to be encrypted (which includes the ESP Pad Length   and Next Header fields) is a multiple of 16 octets.   Because of the algorithm-specific padding requirement, no additional   padding is required to ensure that the ciphertext terminates on a   4-octet boundary.  That is, maintaining a 16-octet block size   guarantees that the ESP Pad Length and Next Header fields will be   right-aligned within a 4-octet word).  Additional padding MAY be   included, as specified in [ESP], as long as the 16-octet block size   is maintained.Kato, et al.                Standards Track                     [Page 3]

RFC 4312                    Camellia Cipher                December 20052.5.  Performance   Performance figures of Camellia are available at [Camellia-Web].   This web site also includes performance comparison with the AES   cipher and other AES finalists.  The NESSIE project [NESSIE] has   reported performance of Optimized Implementations independently.3.  ESP Payload   The ESP payload is made up of the IV followed by raw cipher-text.   Thus, the payload field, as defined in [ESP], is broken down   according to the following diagram:   +---------------+---------------+---------------+---------------+   |                                                               |   +               Initialization Vector (16 octets)               +   |                                                               |   +---------------+---------------+---------------+---------------+   |                                                               |   ~ Encrypted Payload (variable length, a multiple of 16 octets)  ~   |                                                               |   +---------------------------------------------------------------+   The IV field MUST be the same size as the block size of the cipher   algorithm being used.  The IV MUST be chosen at random, and MUST be   unpredictable.   Including the IV in each datagram ensures that each received datagram   can be decrypted, even when some datagrams are dropped or re-ordered   in transit.   To avoid CBC encryption of very similar plaintext blocks in different   packets, implementations MUST NOT use a counter or other low   Hamming-distance source for IVs.3.1.  ESP Algorithmic Interactions   Currently, there are no known issues regarding interactions between   the Camellia and other aspects of ESP, such as the use of certain   authentication schemes.3.2.  Keying Material   The minimum number of bits sent from the key exchange protocol to the   ESP algorithm must be greater than or equal to the key size.  The   cipher's encryption and decryption key is taken from the first 128,   192, or 256 bits of the keying material.Kato, et al.                Standards Track                     [Page 4]

RFC 4312                    Camellia Cipher                December 20054.  Interaction with Internet Key Exchange [IKE]   Camellia was designed to follow the same API as the AES cipher.   Therefore, this section defines only Phase 1 Identifier and Phase 2   Identifier.  Any other consideration related to interaction with IKE   is the same as that of the AES cipher.  Details can be found in   [AES-IPSEC].4.1.  Phase 1 Identifier   For Phase 1 negotiations, IANA has assigned an Encryption Algorithm   ID of 8 for CAMELLIA-CBC.4.2.  Phase 2 Identifier   For Phase 2 negotiations, IANA has assigned an ESP Transform   Identifier of 22 for ESP_CAMELLIA.5.  Security Considerations   Implementations are encouraged to use the largest key sizes they can,   taking into account performance considerations for their particular   hardware and software configuration.  Note that encryption   necessarily affects both sides of a secure channel, so such   consideration must take into account not only the client side, but   also the server.  However, a key size of 128 bits is considered   secure for the foreseeable future.   No security problem has been found on Camellia [CRYPTREC][NESSIE].6.  IANA Considerations   IANA has assigned Encryption Algorithm ID = 8 to CAMELLIA-CBC.   IANA has assigned ESP Transform Identifier = 22 to ESP_CAMELLIA.7.  Acknowledgements    Portions of this text were unabashedly borrowed from [AES-IPSEC].    This work was done when the first author worked for NTT.Kato, et al.                Standards Track                     [Page 5]

RFC 4312                    Camellia Cipher                December 20058.  References8.1.  Normative References   [Camellia-Desc]  Matsui, M., Nakajima, J., and S. Moriai, "A                    Description of the Camellia Encryption Algorithm",RFC 3713, April 2004.   [ESP]            Kent, S., "IP Encapsulating Security Payload (ESP)",RFC 4303, December 2005.8.2.  Informative References   [AES]            NIST, FIPS PUB 197, "Advanced Encryption Standard                    (AES)," November 2001.http://csrc.nist.gov/publications/fips/fips197/fips-197.{ps,pdf}.   [AES-IPSEC]      Frankel, S., Glenn, R., and S. Kelly, "The AES-CBC                    Cipher Algorithm and Its Use With IPsec,"RFC 3602,                    September 2003.   [ARCH]           Kent, S. and R. Atkinson, "Security Architecture for                    the Internet Protocol",RFC 2401, November 1998.   [Camellia-CMS]   Moriai, S. and A. Kato, "Use of the Camellia                    Encryption Algorithm in Cryptographic Message Syntax                    (CMS)",RFC 3657, January 2004.   [Camellia-Web]   Camellia web site:http://info.isl.ntt.co.jp/camellia/.   [CRYPTO-S]       Schneier, B., "Applied Cryptography Second Edition",                    John Wiley & Sons, New York, NY, 1995, ISBN 0-471-                    12845-7.   [CRYPTREC]       Information-technology Promotion Agency (IPA),                    Japan, CRYPTREC.http://www.ipa.go.jp/security/enc/CRYPTREC/ index-                    e.html.   [IKE]            Harkins, D. and D. Carrel, "The Internet Key                    Exchange (IKE)",RFC 2409, November 1998.   [SP800-38a]      Dworkin, M., "Recommendation for Block Cipher Modes                    of Operation - Methods and Techniques", NIST Special                    Publication 800-38A, December 2001.Kato, et al.                Standards Track                     [Page 6]

RFC 4312                    Camellia Cipher                December 2005   [NESSIE]         The NESSIE project (New European Schemes for                    Signatures, Integrity and Encryption),http://www.cosic.esat.kuleuven.ac.be/nessie/.   [ROAD]           Thayer, R., Doraswamy, N., and R. Glenn, "IP                    Security Document Roadmap",RFC 2411, November 1998.   [RFC-2119]       Bradner, S., "Key words for use in RFCs to Indicate                    Requirement Levels",BCP 14,RFC 2119, March 1997.Authors' Addresses   Akihiro Kato   NTT Software Corporation   Phone: +81-45-212-7934   Fax:   +81-45-212-7410   EMail: akato@po.ntts.co.jp   Shiho Moriai   Sony Computer Entertainment Inc.   Phone: +81-3-6438-7523   Fax:   +81-3-6438-8629   EMail: camellia@isl.ntt.co.jp (Camellia team)          shiho@rd.scei.sony.co.jp (Shiho Moriai)   Masayuki Kanda   Nippon Telegraph and Telephone Corporation   Phone: +81-46-859-2437   Fax:   +81-46-859-3365   EMail: kanda@isl.ntt.co.jpKato, et al.                Standards Track                     [Page 7]

RFC 4312                    Camellia Cipher                December 2005Full Copyright Statement   Copyright (C) The Internet Society (2005).   This document is subject to the rights, licenses and restrictions   contained inBCP 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 inBCP 78 andBCP 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 athttp://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.Acknowledgement   Funding for the RFC Editor function is currently provided by the   Internet Society.Kato, et al.                Standards Track                     [Page 8]