Network Working Group S. Kanno
Internet-Draft NTT Software Corporation
Intended status: Standards Track M. Kanda
Expires: October 8, 2009 Nippon Telegraph and Telephone
Corporation
April 6, 2009
The Camellia Algorithm and Its Use wiht the Secure Real-time Transport
Protocol(SRTP)
draft-avt-kanno-srtp-camellia-00
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Abstract
This document describes the use of the Camellia block cipher
algorithm in the Secure Real-time Transport Protocol (SRTP) for
providing confidentiality for the Real-time Transport Protocol (RTP)
traffic and for the control traffic for RTP, the Real-time Transport
Control Protocol (RTCP).
1. Introduction
This document describes the use of the Camellia [RFC3713] block
cipher algorithm in the Secure Real-time Transport Protocol (SRTP)
[RFC3711] for providing confidentiality for the Real-time Transport
Protocol (RTP) [RFC3550] traffic and for the control traffic for RTP,
the Real-time Transport Control Protocol (RTCP) [RFC3550].
1.1. Camellia
Camellia is a symmetric cipher with a Feistel structure. Camellia
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 Advanced Encryption Standard (AES)
[FIPS.197.2001].
Camellia supports 128-bit block size and 128-, 192-, and 256-bit key
lengths, i.e., the same interface specifications as the AES.
Therefore, it is easy to implement Camellia based algorithms by
replacing the AES block of AES based algorithms with a Camellia
block.
Camellia already has been adopted by the IETF and other international
standardization organizations; in particular, the IETF has published
specifications for the use of Camellia with IPsec [RFC4312], TLS
[RFC4132], S/MIME [RFC3657] and XML Security [RFC4051]. Camellia is
one of the three ISO/IEC international standard [ISO/IEC 18033-3]
128-bit block ciphers (Camellia, AES, and SEED). 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
Japanese CRYPTREC (Cryptography Research and Evaluation Committees)
[CRYPTREC].
Since optimized source code is provided under several open source
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licenses [open source license], Camellia is also adopted by several
open source projects (OpenSSL, GnuTLS, FreeBSD, and Linux). Camellia
is also adopted by Mozilla and Camellia is ready for use with Firefox
3.0 released in June 2008.
The algorithm specification and object identifiers are described in
[RFC3713].
The Camellia web site [Camellia web site] contains a wealth of
information about Camellia, including detailed specification,
security analysis, performance figures, reference implementation,
optimized implementation, test vectors(TV), and intellectual property
information.
1.2. Terminology
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
[RFC2119].
2. Camellia Algorithm Suites for SRTP
All symmetric block cipher algorithms share common characteristics
and valuables, including mode, key size, weak keys, and block size.
Camellia algorithm is specified as well as AES, those relations are
following:
a) Camellia-CTR comply with [RFC3711]
b) Camellia-GCM/CCM comply with [AES-GCM/CCM]
3. Default and mandatory-to-implement Transforms
The default transforms also are mandatory-to-implement transforms in
SRTP. Of course, "mandatory-to-implement" does not imply "mandatory-
to-use". Table 1 summarizes the pre-defined transforms. The default
values below are valid for the pre-defined transforms.
man.-to-impl. optional default
encryption Camellia-CTR Camellia-CCM, -GCM Camellia-CTR
message integrity HMAC-SHA1 Camellia-CCM, -GCM HMAC-SHA1
key derivation (PRF) Camellia-CTR - Camellia-CTR
Table 1: Mandatory-to-implement, optional and default transforms in
SRTP and SRTCP.
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4. Security Considerations
At the time of writing this document, there are no known weak keys
for Camellia. Also, No security problem has been found on Camellia.
Camellia is secure against all known attacks including Differential
cryptanalysis, linear cryptanalysis, and related key attacks.
The security considerations in RFC 5289 [RFC3711] and Draft of AES-
GCM and AES-CCM for SRTP [AES-GCM/CCM] apply to this document as
well.
5. IANA Considerations
RFC 4568 [RFC4568] defines SRTP "crypto suites"; also, [AES-GCM/CCM]
defines a crypto suite corresponds to a particular AEAD algorithm in
SRTP. In order to allow SDP to signal the use of the algorithms
defined in this document, IANA will register the following crypto
suites into the subregistry for SRTP crypto suites under the SRTP
transport of the SDP Security Descriptions:
srtp-crypto-suite-ext = "CAMELLIA_CM_128_HMAC_SHA1_80" /
"CAMELLIA_CM_128_HMAC_SHA1_32" /
"AEAD_CAMELLIA_128_GCM" /
"AEAD_CAMELLIA_256_GCM" /
"AEAD_CAMELLIA_128_GCM_8" /
"AEAD_CAMELLIA_256_GCM_8" /
"AEAD_CAMELLIA_128_GCM_12" /
"AEAD_CAMELLIA_256_GCM_12" /
"AEAD_CAMELLIA_128_CCM" /
"AEAD_CAMELLIA_256_CCM" /
srtp-crypto-suite-ext
6. Test Vectors
TBD.
7. References
7.1. Normative References
[AES-GCM/CCM]
McGrew, D., "AES-GCM and AES-CCM Authenticated Encryption
in Secure RTP (SRTP)", draft-mcgrew-srtp-aes-gcm-00 (work
in progress), October 2008.
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[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC3550] Schulzrinne, H., Casner, S., Frederick, R., and V.
Jacobson, "RTP: A Transport Protocol for Real-Time
Applications", STD 64, RFC 3550, July 2003.
[RFC3711] Baugher, M., McGrew, D., Naslund, M., Carrara, E., and K.
Norrman, "The Secure Real-time Transport Protocol (SRTP)",
RFC 3711, March 2004.
[RFC3713] Matsui, M., Nakajima, J., and S. Moriai, "A Description of
the Camellia Encryption Algorithm", RFC 3713, April 2004.
[RFC4568] Andreasen, F., Baugher, M., and D. Wing, "Session
Description Protocol (SDP) Security Descriptions for Media
Streams", RFC 4568, July 2006.
7.2. Informative References
[CRYPTREC]
Information-technology Promotion Agency (IPA),
"Cryptography Research and Evaluation Committees",
<http://www.ipa.go.jp/security/enc/CRYPTREC/index-e.html>.
[Camellia web site]
"Camellia web site",
<http://info.isl.ntt.co.jp/camellia/>.
[FIPS.197.2001]
National Institute of Standards and Technology, "Advanced
Encryption Standard (AES)", FIPS PUB 197, November 2001, <
http://csrc.nist.gov/publications/fips/fips197/
fips-197.pdf>.
[ISO/IEC 18033-3]
International Organization for Standardization,
"Information technology - Security techniques - Encryption
algorithms - Part 3: Block ciphers", ISO/IEC 18033-3,
July 2005.
[NESSIE] "The NESSIE project (New European Schemes for Signatures,
Integrity and Encryption)",
<http://www.cosic.esat.kuleuven.ac.be/nessie/>.
[RFC3657] Moriai, S. and A. Kato, "Use of the Camellia Encryption
Algorithm in Cryptographic Message Syntax (CMS)",
RFC 3657, January 2004.
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[RFC4051] Eastlake, D., "Additional XML Security Uniform Resource
Identifiers (URIs)", RFC 4051, April 2005.
[RFC4132] Moriai, S., Kato, A., and M. Kanda, "Addition of Camellia
Cipher Suites to Transport Layer Security (TLS)",
RFC 4132, July 2005.
[RFC4312] Kato, A., Moriai, S., and M. Kanda, "The Camellia Cipher
Algorithm and Its Use With IPsec", RFC 4312,
December 2005.
[open source license]
"Camellia open source software",
<http://info.isl.ntt.co.jp/crypt/eng/camellia/
source.html>.
Authors' Addresses
Satoru Kanno
NTT Software Corporation
Phone: +81-45-212-7577
Fax: +81-45-212-9800
Email: kanno-s@po.ntts.co.jp
Masayuki Kanda
Nippon Telegraph and Telephone Corporation
Phone: +81-422-59-3456
Fax: +81-422-59-4015
Email: kanda.masayuki@lab.ntt.co.jp
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