CAST-256
This article includes a list of general references, but it lacks sufficient corresponding inline citations. (September 2013) |
General | |
---|---|
Designers | Carlisle Adams, Stafford Tavares, Howard Heys, Michael Wiener |
First published | 1998 |
Derived from | CAST-128 |
Cipher detail | |
Key sizes | 128, 160, 192, 224, or 256 bits |
Block sizes | 128 bits |
Structure | generalised Feistel network (Type 1)[1] |
Rounds | 48 |
In cryptography, CAST-256 (or CAST6) is a symmetric-key block cipher published in June 1998. It was submitted as a candidate for the Advanced Encryption Standard (AES); however, it was not among the five AES finalists. It is an extension of an earlier cipher, CAST-128; both were designed according to the "CAST" design methodology invented by Carlisle Adams and Stafford Tavares. Howard Heys and Michael Wiener also contributed to the design.
CAST-256 uses the same elements as CAST-128, including S-boxes, but is adapted for a block size of 128 bits – twice the size of its 64-bit predecessor. (A similar construction occurred in the evolution of RC5 into RC6). Acceptable key sizes are 128, 160, 192, 224 or 256 bits. CAST-256 is composed of 48 rounds, sometimes described as 12 "quad-rounds", arranged in a generalized Feistel network.
In RFC 2612, the authors state that, "The CAST-256 cipher described in this document is available worldwide on a royalty-free and licence-free basis for commercial and non-commercial uses."
Currently, the best public cryptanalysis of CAST-256 in the standard single secret key setting that works for all keys is the zero-correlation cryptanalysis breaking 28 rounds with 2246.9 time and 298.8 data.[2]
References
- ^ Hoang, Viet Tung; Rogaway, Phillip (2010). "On Generalized Feistel Networks". LNCS 6223. CRYPTO 2010. USA: Springer. pp. 613–630.
- ^ Bogdanov, Andrey; Leander, Gregor; Nyberg, Kaisa; Wang, Meiqin (2012). "Integral and multidimensional linear distinguishers with correlation zero" (PDF). Lecture Notes in Computer Science. 7658. Asiacrypt 2012: 244–261. doi:10.1007/978-3-642-34961-4.
See also
External links
- CAST-256 by John J. G. Savard
- 256bit Ciphers - CAST256 Reference implementation and derived code
- Standard Cryptographic Algorithm Naming: CAST-256
- RFC 2612