Analysis of the Bit-Search Generator and Sequence Compression Techniques

Abstract. Algebraic attacks on stream ciphers apply (at least theoretically) to all LFSR-based stream ciphers that are clocked in a simple and/or easily predictable way. One interesting approach to help resist such attacks is to add a component that de-synchronizes the output bits of the cipher from the clock of the LFSR. The Bit-search generator, recently proposed by Gouget and Sibert, is inspired by the so-called SelfShrinking Generator which is known for its simplicity (conception and implementation-wise) linked with some interesting properties. In this paper, we introduce two modified versions of the BSG, called MBSG and ABSG, and some of their properties are studied. We apply a range of cryptanalytic techniques in order to compare the security of the BSGs.

• Type: Conference
• Year: 2005
• Where: FSE
• Authors: Aline Gouget, Hervé Sibert, Côme Berbain, Nicolas Courtois, Blandine Debraize, Chris J. Mitchell
• Keywords: Cryptography, FSE 2005, LFSR-based Stream Ciphers, So-called Selfshrinking Generator, Stream Ciphers