Security analysis of the song-mitchell authentication protocol for low-cost RFID tags

In this paper, we describe an attack against one of the most efficient authentication protocols for low-cost RFID tags recently proposed by Song and Mitchell. A weak attacker, i.e. an attacker that has no access to the internal data of a tag, is able to impersonate a legitimate reader/server, and to desynchronize a tag. The attack is very efficient and has minimal computational complexity. Finally, we propose a simple solution to fix the flaw.