Mimicry Attacks Against Wireless Link Signature and New Defense Using Time-Synched Link Signature

摘要

Wireless link signature is a physical layer authentication mechanism, using the multipath effect between a transmitter and a receiver to provide authentication of wireless signals. This paper identifies a new attack, called mimicry attack, against the existing wireless link signature schemes. An attacker can forge a legitimate transmitter’s link signature as long as it knows the legitimate signal at the receiver’s location, and the attacker does not have to be at exactly the same location as the legitimate transmitter. We also extend the mimicry attack to multiple-input multiple-output (MIMO) systems, and conclude that the mimicry attack is feasible only when the number of attacker’ antennas is equal to or larger than that of the receiver’s antennas. To defend against the mimicry attack, this paper proposes a novel construction for wireless link signature, called time-synched link signature, by integrating cryptographic protection and time factor into wireless physical layer features. Experimental results confirm that the mimicry attack is a real threat and the newly proposed time-synched link signatures are effective in physical layer authentication.