On the (In)security of the Ciphers and Protocols of GSM.
Eli Biham (Technion, Haifa, Israel)

In this talk we describe the ciphers and protocols used for the GSM cellular phone network, and discuss the (in)security of the system. We describe several techniques to attack the ciphers A5/2 and A5/1, and how they can be applied as a ciphertext-only attack. We also show that active attacks on the protocols can recover keys of ciphers that are not used during that transmission. As a result, it is possible to listen in to GSM phone conversations, steal calls during the conversation, and even issue new calls on behalf of (and paid by) an attacked phone.

This talk summarizes several papers on this issue. This is a joint work with Elad Barkan and Nathan Keller.