Internet Engineering Task Force (IETF) S. Kanno Request for Comments: 6367 NTT Software Corporation Category: Informational M. Kanda ISSN: 2070-1721 NTT September 2011
Addition of the Camellia Cipher Suites to Transport Layer Security (TLS)
Abstract
This document specifies forty-two cipher suites for the Transport Security Layer (TLS) protocol to support the Camellia encryption algorithm as a block cipher.
Status of This Memo
This document is not an Internet Standards Track specification; it is published for informational purposes.
This document is a product of the Internet Engineering Task Force (IETF). It represents the consensus of the IETF community. It has received public review and has been approved for publication by the Internet Engineering Steering Group (IESG). Not all documents approved by the IESG are a candidate for any level of Internet Standard; see Section 2 of RFC 5741.
Information about the current status of this document, any errata, and how to provide feedback on it may be obtained at http://www.rfc-editor.org/info/rfc6367.
Copyright Notice
Copyright (c) 2011 IETF Trust and the persons identified as the document authors. All rights reserved.
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Kanno & Kanda Informational [Page 1]
RFC 6367 Camellia Cipher Suites for TLS September 2011
The Camellia cipher suites are already specified in RFC 5932 [15] with SHA-256-based Hashed Message Authentication Code (HMAC) using asymmetric key encryption. This document proposes the addition of new cipher suites to the Transport Layer Security (TLS) [8] protocol to support the Camellia [4] cipher algorithm as a block cipher algorithm. The proposed cipher suites include variants using the SHA-2 family of cryptographic hash functions [13] and Galois Counter Mode (GCM) [14]. Elliptic curve cipher suites and pre-shared key (PSK) [5] cipher suites are also included.
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 RFC 2119 [3].
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RFC 6367 Camellia Cipher Suites for TLS September 2011
The twenty cipher suites use the same asymmetric key algorithms as those in the previous section but use the authenticated encryption modes defined in TLS 1.2 [8] with Camellia in GCM [14].
The fourteen cipher suites describe PSK cipher suites. The first six cipher suites use Camellia with GCM, and the next eight cipher suites use Camellia with SHA-2 family HMAC using asymmetric key encryption or the elliptic curve cryptosystem.
This document describes cipher suites based on Camellia cipher using CBC mode and GCM. The details are as follows.
The CAMELLIA_128_CBC cipher suites use Camellia [4] in CBC mode with a 128-bit key and 128-bit Initialization Vector (IV); the CAMELLIA_256_CBC cipher suites use a 256-bit key and 128-bit IV.
Advanced Encryption Standard (AES) [19] authenticated encryption with additional data algorithms, AEAD_AES_128_GCM and AEAD_AES_256_GCM, are described in RFC 5116 [7]. AES GCM cipher suites for TLS are described in RFC 5288 [9]. AES and Camellia share common characteristics including key sizes and block length. CAMELLIA_128_GCM and CAMELLIA_256_GCM are defined according to those of AES.
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RFC 6367 Camellia Cipher Suites for TLS September 2011
The hash algorithms and pseudorandom function (PRF) algorithms for TLS 1.2 [8] SHALL be as follows:
a. The cipher suites ending with _SHA256 use HMAC-SHA-256 [1] as the MAC algorithm. The PRF is the TLS PRF [8] with SHA-256 [13] as the hash function.
b. The cipher suites ending with _SHA384 use HMAC-SHA-384 [1] as the MAC algorithm. The PRF is the TLS PRF [8] with SHA-384 [13] as the hash function.
When used with TLS versions prior to 1.2 (TLS 1.0 [2] and TLS 1.1 [6]), the PRF is calculated as specified in the appropriate version of the TLS specification.
At the time of writing this document, there are no known weak keys for Camellia. Additionally, no security problems with Camellia have been found (see NESSIE [16], CRYPTREC [17], and LNCS 5867[18]).
The security considerations in previous RFCs (RFC 5116 [7], RFC 5289 [10], and RFC 5487 [11]) apply to this document as well.
[14] Dworkin, M., "Recommendation for Block Cipher Modes of Operation: Galois/Counter Mode (GCM) for Confidentiality and Authentication", Special Publication 800-38D, April 2006, <http://csrc.nist.gov/publications/nistpubs/800-38D/ SP-800-38D.pdf>.
RFC 6367 Camellia Cipher Suites for TLS September 2011
[18] Mala, H., Shakiba, M., Dakhilalian, M., and G. Bagherikaram, "New Results on Impossible Differential Cryptanalysis of Reduced Round Camellia-128", LNCS 5867, November 2009, <http://www.springerlink.com/content/e55783u422436g77/>.