Cryptology ePrint Archive: Report 2010/435

The Improbable Differential Attack: Cryptanalysis of Reduced Round CLEFIA

Cihangir Tezcan

Abstract: In this paper we present a new statistical cryptanalytic technique that we call improbable differential cryptanalysis which uses a differential that is less probable when the correct key is used. We provide data complexity estimates for this kind of attacks and we also show a method to expand impossible differentials to improbable differentials. By using this expansion method, we cryptanalyze 13, 14, and 15-round CLEFIA for the key sizes of length 128, 192, and 256 bits, respectively. These are the best cryptanalytic results on CLEFIA up to this date.

Category / Keywords: secret-key cryptography / Cryptanalysis, Improbable differential attack, CLEFIA

Publication Info: To appear in Indocrypyt 2010

Date: received 8 Aug 2010, last revised 16 Oct 2010

Contact author: cihangir tezcan at epfl ch

Available format(s): PDF | BibTeX Citation

Note: Updated to the version that will appear in Indocrypyt 2010.

Version: 20101016:132544 (All versions of this report)

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