Design of Physical Layer Challenge Response Authentication With RIS and Multiple-Antenna Devices

This paper focuses on the challenge-response physical-layer authentication (CR-PLA) scheme where a reflecting intelligent surface (RIS) is under the control of a receiving base station (BS) (Bob) who aims at checking if received messages come from a legitimate user equipment (UE) Alice or from an impersonating device (Trudy). To this end, Bob sets a random configuration of the RIS which remains secret to the attacker, and verifies that the channel estimated on the received message corresponds to the set configuration. We design the probability distribution of RIS configurations chosen by the verifier to maximize average capacity while satisfying an upper bound on missed detection (MD) probability for a given false alarm (FA) probability. The balance of communication and security metrics demonstrated by the numerical results shows the effectiveness and potential of the CR-PLA scheme.