Physical-Layer Challenge-Response Authentication with IRS and Single-Antenna Devices

This paper focuses on a novel challenge-response physical layer authentication (CR-PLA) mechanism for wireless communications. It integrates an intelligent reflecting surface (IRS) under the control of the receiver, which operates as a verifier for the identity of the transmitter. In CR-PLA, the verifier randomly configures the IRS and then checks that the resulting estimated channel is correspondingly modified. We address the trade-off between communication and security performance, in terms of average signal-to-noise ratio (SNR) and missed detection (MD) probability of an impersonation attack, respectively. In particular, we design the probability distribution of the random IRS configuration that maximizes the average receiver SNR under an upper bound constraint on the MD and false alarm (FA) probabilities, for the special case where both the transmitter and the receiver are equipped with a single antenna. Numerical results demonstrate effective balancing of communication metrics and security requirements, suggesting that CR-PLA is a promising solution for future secure wireless communication.

I. Introduction

Establishing whether a received message truly comes from the legitimate sender or has been forged by an impersonating attacker describes the user authentication problem. If unau-thenticated messages are accepted, several risks might occur that go from denial of service to privacy or the loss of control of devices, e.g., in Internet of Things (IoT) contexts.