In this paper, a challenge–response physical-layer authentication (CR-PLA) scheme is proposed in which the receiver uses an Intelligent Reflecting Surface (IRS) to validate the identity of a single-antenna transmitter. The method operates by randomly selecting IRS phase configurations and checking whether the corresponding estimated channel matches the expected response, enabling authentication without relying on traditional cryptographic keys. The study analyzes the resulting authentication performance by deriving expressions for false alarm and missed detection probabilities, and examines how these metrics depend on average SNR and channel conditions. The authors also optimize the probability distribution of IRS phase shifts to maximize communication performance while satisfying strict security constraints. Numerical results demonstrate that appropriate IRS randomness enables an effective balance between link quality and authentication robustness, making CR-PLA a promising approach for secure future wireless systems.
Physical-Layer_Challenge-Response_Authentication_with_IRS_and_Single-Antenna_Devices