Hybrid Channel- and Coding-Based Challenge-Response Physical-Layer Authentication
Laura Crosara, Mahtab Mirmohseni, Stefano Tomasin
TL;DR
The paper tackles authenticating wireless messages at the physical layer when the receiver can partly control the channel, such as with programmable channels or IRSs. It introduces a hybrid CR-PLA framework that fuses channel-based authentication with coding-based secrecy, enabling authentication through both CSI consistency and secret-key verification. The authors provide analytical bounds for security and show through numerical results that the hybrid approach increases the effective secret-bit budget, especially when the attacker’s channel is weaker than the legitimate one, and under higher frame counts. This work offers practical insights for securing wireless links in next-generation networks where partial channel control is feasible.
Abstract
This letter proposes a new physical layer authentication mechanism operating at the physical layer of a communication system where the receiver has partial control of the channel conditions (e.g., using an intelligent reflecting surface). We aim to exploit both instantaneous channel state information (CSI) and a secret shared key for authentication. This is achieved by both transmitting an identifying key by wiretap coding (to conceal the key from the attacker) and checking that the instantaneous CSI corresponds to the channel configuration randomly selected by the receiver. We investigate the trade-off between the pilot signals used for CSI estimation and the coding rate (or key length) to improve the overall security of the authentication procedure.