Cryptology ePrint Archive: Report 2014/860

Differential Factors: Improved Attacks on SERPENT

Cihangir Tezcan and Ferruh Özbudak

Abstract: A differential attack tries to capture the round keys corresponding to the S-boxes activated by a differential. In this work, we show that for a fixed output difference of an S-box, it may not be possible to distinguish the guessed keys that have a specific difference. We introduce these differences as differential factors. Existence of differential factors can reduce the time complexity of differential attacks and as an example we show that the 10, 11, and 12-round differential-linear attacks of Dunkelman et al. on SERPENT can actually be performed with time complexities reduced by a factor of 4, 4, and 8, respectively.

Category / Keywords: secret-key cryptography / S-box, differential factor, Serpent, differential-linear attack

Original Publication (in the same form): Lightsec 2014

Date: received 20 Oct 2014, last revised 2 Nov 2014

Contact author: cihangir at metu edu tr

Available format(s): PDF | BibTeX Citation

Note: Some typos are corrected.

Version: 20141102:103856 (All versions of this report)

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