Some attacks on the Bit-search generator

Summary, in English

The bit-search generator (BSG) was proposed in 2004 and can be seen as a variant of the shrinking and self-shrinking generators. It has the advantage that it works at rate 1/3 using only one LFSR and some selection logic. We present various attacks on the BSG based on the fact that the output sequence can be uniquely defined by the differential of the input sequence. By knowing only a small part of the output sequence we can reconstruct the key with complexity O(L(3)2(0.5L)). This complexity can be significantly reduced in a data/time tradeoff manner to achieve a complexity of O(L(3)2(0.27)L) if we have O(2(0.27L)) of keystream. We also propose a distinguishing attack that can be very efficient if the feedback polynomial is not carefully chosen.

• Author: Martin Hell; Thomas Johansson
• Department/s: Department of Electrical and Information Technology
• Publishing year: 2005
• Language: English
• Pages: 215-227
• Publication/Series: Fast Software Encryption / Lecture Notes in Computer Science
• Volume: 3557
• Links: http://dx.doi.org/10.1007/11502760_14
• Document type: Conference paper
• Publisher: Springer
• Topic: Electrical Engineering, Electronic Engineering, Information Engineering
• Conference name: Fast Software Encryption 12th International Workshop, FSE 2005
• Conference date: 2005-02-21 - 2005-02-23
• Conference place: Paris, France
• Status: Published
• ISBN/ISSN/Other: ISSN: 1611-3349; ISSN: 0302-9743; ISBN: 978-3-540-26541-2