RFID Distance Bounding Protocol with Mixed Challenges to Prevent Relay Attacks

RFID systems suffer from different location-based attacks such as distance fraud, mafia fraud and terrorist fraud attacks. Among them mafia fraud attack is the most serious since this attack can be mounted without the notice of both the reader and the tag. An adversary performs a kind of man-in-the-middle attack between the reader and the tag. It is very difficult to prevent this attack since the adversary does not change any data between the reader and the tag. Recently distance bounding protocols measuring the round-trip time between the reader and the tag have been researched to prevent this attack. All the existing distance bounding protocols based on binary challenges, without final signature, provide an adversary success probability equal to (3/4) n where n is the number of rounds in the protocol. In this paper, we introduce a new protocol based on binary mixed challenges that converges toward the expected and optimal (1/2) n bound. We prove its security in case of both noisy and non-noisy channels.