Cryptology ePrint Archive: Report 2004/232

Extending the Resynchronization Attack

Frederik Armknecht and Joseph Lano and Bart Preneel

Abstract: Synchronous stream ciphers need perfect synchronization between sender and receiver. In practical applications, this is ensured by a resync mechanism. Daemen et al first described attacks on ciphers using such a resync mechanism. In this paper, we extend their attacks in several ways by combining the standard attack with several cryptanalytic techniques such as algebraic attacks and linear cryptanalysis. Our results show that using linear resync mechanisms should be avoided, and give lower bounds for the nonlinearity required from a secure resync mechanism.

Category / Keywords: secret-key cryptography / stream ciphers, cryptanalysis

Publication Info: Extended version of the paper that will appear under the same title in the proceedings of SAC 2004

Date: received 13 Sep 2004, last revised 20 Sep 2004

Contact author: joseph lano at esat kuleuven ac be

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Version: 20040920:173424 (All versions of this report)

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