Improved Results on Algebraic Cryptanalysis ofA5/2

摘要

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.