Cryptology ePrint Archive: Report 2010/485

Cryptanalysis of Block Ciphers Using Almost-Impossible Differentials

Hamid Mala and Mohammad Dakhilalian and Mohsen Shakiba

Abstract: In this paper, inspired from the notion of impossible differentials, we present a model to use differentials that are less probable than a random permutation. We introduce such a distinguisher for 2 rounds of Crypton, and present an attack on 6 rounds of this predecessor AES candidate. As a special case of this idea, we embed parts of the additional rounds around the impossible differential into the distinguisher to make a probabilistic distinguisher with more rounds. We show that with this change, the data complexity is increased but the time complexity may be reduced or increased. Then we discuss that this change in the impossible differential cryptanalysis is commodious and rational when the data complexity is low and time complexity is marginal.

Category / Keywords: secret-key cryptography / Block Cipher, Cryptanalysis, Almost-Impossible Differential, Crypton

Date: received 14 Sep 2010, last revised 14 Sep 2010

Contact author: hamidmala2003 at yahoo com

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Version: 20100915:022008 (All versions of this report)

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