AVT Working Group Seokung Yoon
Internet Draft Joongman Kim
Expires: January 2008 Yoojae Won
Korea Information Security Agency
July 2, 2007
The SEED Cipher Algorithm and Its Use with the Secure Real-time
Transport Protocol (SRTP)
draft-seokung-avt-seed-srtp-00.txt
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Abstract
This document describes the use of SEED block cipher algorithm in the
Secure Real-time Transport Protocol [3] for confidentiality to the
RTP traffic and to the control traffic for RTP, the Real-time
Transport Control Protocol (RTCP).
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Table of Contents
1. Introduction..................................................2
1.1. SEED.....................................................2
1.2. Terminology..............................................3
2. The SEED Cipher Algorithm.....................................3
2.1. Mode.....................................................3
2.2. Key Size and Number of Rounds............................3
2.3. Block Size and Padding...................................3
2.4. Performance..............................................3
3. Security Considerations.......................................3
4. IANA Considerations...........................................4
5. References....................................................4
5.1. Normative References.....................................4
5.2. Informative References...................................4
Author's Addresses...............................................5
Intellectual Property Statement..................................5
Disclaimer of Validity...........................................6
1. Introduction
1.1. SEED
SEED [2] is a national industrial association standard [7] and is
widely used in South Korea for electronic commerce and financial
services that are operated on wired and wireless communications.
SEED is a 128-bit symmetric key block cipher that had been developed
by KISA(Korea Information Security Agency) and a group of experts
since 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.
SEED is easily implemented in various software and hardware because
it is designed to increase the efficiency of memory storage and the
simplicity in generating keys without degrading the security of the
algorithm. In particular, it can be effectively adapted to a
computing environment with restricted resources such as mobile
devices, smart cards and so on.
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1.2. Terminology
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 [1].
2. The SEED Cipher Algorithm
The algorithm specification and object identifiers are described in
[5] [3]. The SEED homepage, http://www.kisa.or.kr/seed/seed_eng.html,
contains a wealth of information about SEED, including a detailed
specification, evaluation report, test vectors, and so on.
2.1. Mode
This document specifies the use of the SEED cipher in the CBC (Cipher
Block Chaining) mode. This mode requires an Initialization Vector IV)
that is the same size as the block size. The IV MUST be chosen at
random and MUST be unpredictable.
2.2. Key Size and Number of Rounds
SEED supports 128-bit key and has the 16-round Feistel structure.
2.3. Block Size and Padding
SEED uses a block size of 16 octets (128 bits).
Padding is required by SEED to maintain a 16-octet (128-bit)
blocksize. Padding must be added such that the data to be encrypted
has a length that is a multiple of 16 octets.
2.4. Performance
Performance figures of SEED are available at
http://www.kisa.or.kr/seed/seed_eng.html.
3. Security Considerations
No security problem has been found on SEED. SEED is secure against
all known attacks including Differential cryptanalysis, linear
cryptanalysis, and related key attacks. The best known attack is only
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an exhaustive search for the key (by [4]). For further security
considerations, the reader is encouraged to read [4], [5], and [6].
4. IANA Considerations
5. References
5.1. Normative References
[1] Bradner, S., "Key words for use in RFCs to Indicate Requirement
Levels", BCP 14, RFC 2119, March 1997.
[2] KISA, "SEED Algorithm Specification",
http://www.kisa.or.kr/seed/seed_eng.html.
[3] M. Baugher, D. McGrew, M. Naslund, E.Carrara, K. Norrman,
"The Secure Real-time Transport Protocol (SRTP)",
RFC 3711, March 2004.
5.2. Informative References
[4] Information-technology Promotion Agency (IPA), Japan, CRYPTREC.
"SEED Evaluation Report", February, 2002
http://www.kisa.or.kr/seed/seed_eng.html.
[5] 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.
[6] KISA, "Self Evaluation Report",
http://www.kisa.or.kr/seed/seed_eng.html.
[7] 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.
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Author's Addresses
Seokung Yoon
Korea Information Security Agency
78, Karak-dong, Songpa-Gu
Seoul 138-160
KOREA
Phone: +82-2-405-5361
FAX : +82-2-405-5319
Email: seokung@kisa.or.kr
Joongman Kim
Korea Information Security Agency
78, Karak-dong, Songpa-Gu
Seoul 138-160
KOREA
Phone: +82-2-405-5314
FAX : +82-2-405-5319
Email: seopo@kisa.or.kr
Yoojae Won
Korea Information Security Agency
78, Karak-dong, Songpa-Gu
Seoul 138-160
KOREA
Phone: +82-2-405-5360
FAX : +82-2-405-5319
Email: yjwon@kisa.or.kr
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