Cryptology ePrint Archive: Report 2008/076

Results from a Search for the Best Linear Approximation of a Block Cipher

Kashif Ali and Howard M. Heys

Abstract: In this paper, we investigate the application of an algorithm to find the best linear approximation of a basic Substitution-Permutation Network block cipher. The results imply that, while it is well known that the S-box used for the Advanced Encryption Standard has good nonlinear properties, it is straightforward to randomly select other S-boxes which are able to provide a similar level of security, as indicated by the exact bias of the best linear approximation found by the algorithm, rather than a simple upper bound on the maximum bias.

Category / Keywords: secret-key cryptography / block ciphers, linear cryptanalysis

Publication Info: Unpublished except as Masters thesis of 1st author.

Date: received 19 Feb 2008

Contact author: howard at engr mun ca

Available format(s): PDF | BibTeX Citation

Version: 20080227:044120 (All versions of this report)

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