The Improbable Differential Attack: Cryptanalysis of Reduced Round CLEFIA

  • Cihangir Tezcan
Part of the Lecture Notes in Computer Science book series (LNCS, volume 6498)


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.


Cryptanalysis Improbable differential attack CLEFIA 


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© Springer-Verlag Berlin Heidelberg 2010

Authors and Affiliations

  • Cihangir Tezcan
    • 1
  1. 1.École Polytechnique Fédérale de LausanneLausanneSwitzerland

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