Network Working Group S. Kanno
Internet-Draft NTT Software Corporation
Intended status: Standards Track M. Kanda
Expires: July 8, 2010 NTT
January 4, 2010
The Camellia Algorithm and Its Use wiht the Secure Real-time Transport
Protocol(SRTP)
draft-avt-kanno-srtp-camellia-01
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).
Status of this Memo
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Copyright Notice
Copyright (c) 2010 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
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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].
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Since optimized source code is provided under several open source
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:
- Camellia-CTR complies with [RFC3711]
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. default
encryption Camellia-CTR Camellia-CTR
message integrity HMAC-SHA1 HMAC-SHA1
key derivation (PRF) Camellia-CTR Camellia-CTR
Table 1: Mandatory-to-implement 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] apply to this
document as well.
5. IANA Considerations
RFC 4568 [RFC4568] defines SRTP "crypto suites"; 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_CTR_128_HMAC_SHA1_80" /
"CAMELLIA_CTR_128_HMAC_SHA1_32" /
srtp-crypto-suite-ext
6. Test Vectors
6.1. Camellia-CTR Test Vectors
Keystream segment length: 1044512 octets (65282 Camellia blocks)
Session Key: 2B7E151628AED2A6ABF7158809CF4F3C
Rollover Counter: 00000000
Sequence Number: 0000
SSRC: 00000000
Session Salt: F0F1F2F3F4F5F6F7F8F9FAFBFCFD0000 (already shifted)
Offset: F0F1F2F3F4F5F6F7F8F9FAFBFCFD0000
Counter Keystream
F0F1F2F3F4F5F6F7F8F9FAFBFCFD0000 B2D8ED5E9E74E2B22F24D190290304F1
F0F1F2F3F4F5F6F7F8F9FAFBFCFD0001 917D4D59E7A62AAA3EC3037481304FAC
F0F1F2F3F4F5F6F7F8F9FAFBFCFD0002 876DDA20079D808ABE045C84FFA50E6B
... ...
F0F1F2F3F4F5F6F7F8F9FAFBFCFDFEFF D3C8AAEA599D89569F4577158BAEFA3B
F0F1F2F3F4F5F6F7F8F9FAFBFCFDFF00 156C6C1985F2DA529B6377C760295A98
F0F1F2F3F4F5F6F7F8F9FAFBFCFDFF01 7920339AFE329CBA9DE8A2FC0D8BAE74
6.2. Key Derivation Test Vectors using Camellia-128 in Counter Mode
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master key: E1F97A0D3E018BE0D64FA32C06DE4139
master salt: 0EC675AD498AFEEBB6960B3AABE6
(1) session key
index DIV kdr: 000000000000
label: 00
master salt: 0EC675AD498AFEEBB6960B3AABE6
-----------------------------------------------
xor: 0EC675AD498AFEEBB6960B3AABE6 (x, PRF input)
x*2^16: 0EC675AD498AFEEBB6960B3AABE60000 (Camellia-CTR input)
cipher key: 259EA7329BD8BCFC0E42D6336F7EC339 (Camellia-CTR output)
(2) session salt
index DIV kdr: 000000000000
label: 02
master salt: 0EC675AD498AFEEBB6960B3AABE6
----------------------------------------------
xor: 0EC675AD498AFEE9B6960B3AABE6 (x, PRF input)
x*2^16: 0EC675AD498AFEE9B6960B3AABE60000 (Camellia-CTR input)
69AF5169A7C7D257D0A19C38D81DF16A (Camellia-CTR ouptut)
cipher salt: 69AF5169A7C7D257D0A19C38D81D
(3) auth key
index DIV kdr: 000000000000
label: 01
master salt: 0EC675AD498AFEEBB6960B3AABE6
-----------------------------------------------
xor: 0EC675AD498AFEEAB6960B3AABE6 (x, PRF input)
x*2^16: 0EC675AD498AFEEAB6960B3AABE60000 (Camellia-CTR input)
akey Camellia input blocks
CA06DDE96B5B0C71F02F878B8D376FCC 0EC675AD498AFEEAB6960B3AABE60000
83750D2E61365F8BE33E6DD24519C5A8 0EC675AD498AFEEAB6960B3AABE60001
17CE96CF61AB9C4F4EEB0689148A7A32 0EC675AD498AFEEAB6960B3AABE60002
0FD78D243DDE852CA7C266D50E077CA7 0EC675AD498AFEEAB6960B3AABE60003
BBCBF3EF45BCE67141ABA950063CF86E 0EC675AD498AFEEAB6960B3AABE60004
73513A989FC1CBC3E8E11FF0DD20 0EC675AD498AFEEAB6960B3AABE60005
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7. References
7.1. Normative References
[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/>.
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[RFC3657] Moriai, S. and A. Kato, "Use of the Camellia Encryption
Algorithm in Cryptographic Message Syntax (CMS)",
RFC 3657, January 2004.
[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: +81-45-212-9803
Fax: +81-45-212-9800
Email: kanno.satoru@po.ntts.co.jp
Masayuki Kanda
NTT
Phone: +81-422-59-3456
Fax: +81-422-59-4015
Email: kanda.masayuki@lab.ntt.co.jp
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