Mutually Clock-Controlled Feedback Shift Registers Provide Resistance to Algebraic Attacks.
ABSTRACT Algebraic attacks have been applied to several types of clock-controlled stream ciphers. However, to date there are no such
attacks in the literature on mutually clock-controlled ciphers. In this paper, we present a preliminary step in this direction
by giving the first algebraic analysis of mutually clock-controlled feedback shift register stream ciphers: the bilateral
stop-and-go generator, A5/1, Alpha 1 and the MICKEY cipher. We show that, if there are no regularly clocked shift registers
included in the system, mutually clock-controlled feedback shift register ciphers appear to be highly resistant to algebraic
attacks. As a demonstration of the weakness inherent in the presence of a regularly clocked shift register, we present a simple
algebraic attack on Alpha 1 based on only 29 keystream bits.
- SourceAvailable from: Anthony Henry DekkerIACR Cryptology ePrint Archive. 01/2010; 2010:203.
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ABSTRACT: Algebraic analysis of A5/2, the weaker version of GSM encryption algorithm, is presented in this article. We have enhanced existing cryptanalysis of A5/2 in terms of data requirement. Experimental results using an implementation of Groebner basis algorithm are presented. It has been found that state bits of the cipher can be recovered in fewer number of data frames than required in a previous efficient attack against GSM communication. Number of data frames required for both known-plaintext and ciphertext-only attacks can be reduced if linearization is replaced by Groebner basis technique without changing the time complexity of attack.12/2007: pages 182-189;
- IACR Cryptology ePrint Archive. 01/2009; 2009:250.