Secret key agreement using a virtual wiretap channel

Key agreement using physical layer properties of communication channels is a well studied problem. iJam is a physical layer key agreement protocol that achieves security by creating a “virtual” wiretap channel for the adversary through a subprotocol between the sender and the receiver that uses self-jamming by the receiver. The protocol was implemented and its security was shown through extensive experiments. The self-jamming subprotocol of iJam was later modelled as a wiretap channel and used for designing a secure message transmission protocol with provable security. We use the same wiretap model of the subprotocol to design secret key agreement protocols with provable security. We propose two protocols that use the wiretap channel once from Alice to Bob, and a protocol that uses two wiretap channels, one from Alice to Bob, and one in the opposite direction. We provide security proof and efficiency analysis for the protocols. The protocols effectively give physical layer security protocols that can be implemented and have provable security. We discuss our results and propose directions for future research.