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A faster cryptanalysis of the self-shrinking generator

  • Miodrag J. Mihaljević
Session 5: Stream Ciphers
Part of the Lecture Notes in Computer Science book series (LNCS, volume 1172)

Abstract

A novel algorithm for cryptanalysis of the self-shrinking generator is presented and discussed, assuming that number of the shift register feedback taps is large and that length of the available generator output sequence is under a certain limit. It is baseo on a probabilistic approach and employes the generator output sequence not only for the hypothesis testing, but also for reducing the set of hypothesis which have to be tested. When the shift register length is L and the characteristic polynomial is known, the novel algorithm ensures the cryptanalysis with overall compexity 2L−l, l ≤ L/2, assuming that required length of the generator output sequence is not greater than \(\ell 2^{L/2} \left( {\mathop {L/2}\limits_\ell } \right)^{ - 1}\). The proposed algorithm yields significant average gain of 2l−0.25L in comparison with the best one published so far, which can work under the assumed conditions.

Key words

cryptology binary sequence generators shift registers self-shrinking generator cryptanalysis 

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Copyright information

© Springer-Verlag Berlin Heidelberg 1996

Authors and Affiliations

  1. 1.Institute of Applied Mathematics and Electronics Institute of MathematicsAcademy of Arts and SciencesYugoslavia

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