Cryptology ePrint Archive: Report 2013/288

Key Classification Attack on Block Ciphers

Maghsoud Parviz and Seyed Hassan Mousavi and Saeed Mirahmadi

Abstract: In this paper, security analysis of block ciphers with key length greater than block length is proposed. For a well-designed block cipher with key length k and block length n s.t. k>n and for all P, C, there are 2^{k-n} keys which map P to C. For given block cipher, if there is an efficient algorithm that can classify such keys, we propose an algorithm will be able to recover the secret key with complexity O(max{2^n, 2^{k-n}}). We apply this method on 2-round block cipher KASUMI.

Category / Keywords: Block cipher, Key classes, key length, block length, KASUMI

Date: received 16 May 2013, last revised 23 May 2013

Contact author: shnmousavi_iut at yahoo fr

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Version: 20130523:162237 (All versions of this report)

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