Slid Pairs in the Initialisation of the A5/1 Stream Cipher

Alhamdan, A, Bartlett, H., Dawson, Ed., Simpson, L. and Wong, K.K.

    A5/1 is a shift register based stream cipher which uses a majority clocking rule to update its registers. It is designed to provide privacy for the GSM system. In this paper, we analyse the initialisation process of A5/1. We demonstrate a sliding property of the A5/1 cipher, where every valid internal state is also a legitimate loaded state and multiple key-IV pairs produce phase shifted keystream sequences. We describe a possible ciphertext only attack based on this property.
Cite as: Alhamdan, A, Bartlett, H., Dawson, Ed., Simpson, L. and Wong, K.K. (2013). Slid Pairs in the Initialisation of the A5/1 Stream Cipher. In Proc. Information Security 2013 (AISC 2013) Adelaide, Australia. CRPIT, 138. Thomborson, C. and Parampalli. U. Eds., ACS. 3-12
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