  Re-configurable Intelligent Surfaces (RIS) technology is increasingly
becoming a potential component for next-generation wireless networks, offering
enhanced performance in terms of throughput, spectral, and energy efficiency.
However, the broadcast nature of RIS-assisted wireless communication makes it
vulnerable to malicious attacks at the physical layer. At the same time,
physical layer authentication is gaining popularity as a solution to secure
wireless networks, thwarting different attacks such as cloning, spoofing, and
impersonation by using the random features of the physical layer.
  In this paper, we investigate RIS-assisted wireless communication systems to
unlock the potential of using RIS for physical layer authentication (PLA). In
particular, we exploit two distinct features of the physical layer: pathloss
and channel impulse response (CIR) for PLA in RIS-assisted wireless
communication. We construct hypothesis tests for the estimated features and
derive closed-form error expressions. Further, we consider the critical error,
i.e., missed detection, as our objective function to minimize by optimizing the
phase shift of the RIS pannel. We compare the performance of our proposed
mechanisms with PLA schemes using the same features but with no RIS.
Furthermore, we thoroughly evaluate our proposed schemes using performance
metrics such as the probability of false alarm (PFA), the probability of missed
detection (PMD), and the receiver operating characteristic (ROC) curves. The
results demonstrate a clear positive impact of RIS on PLA, as it effectively
reduces PMD values to zero when determining the optimal phase shift.
