Covariance-Robust Dynamic Watermarking
This addresses attack detection for cyberphysical systems like autonomous vehicles, but it is incremental as it builds on existing dynamic watermarking methods by relaxing assumptions about noise distribution knowledge.
The paper tackles the problem of attack detection in cyberphysical systems by developing a covariance-robust dynamic watermarking method that handles uncertainties in measurement noise covariance, showing efficacy in empirical examples based on autonomous vehicle simulations.
Attack detection and mitigation strategies for cyberphysical systems (CPS) are an active area of research, and researchers have developed a variety of attack-detection tools such as dynamic watermarking. However, such methods often make assumptions that are difficult to guarantee, such as exact knowledge of the distribution of measurement noise. Here, we develop a new dynamic watermarking method that we call covariance-robust dynamic watermarking, which is able to handle uncertainties in the covariance of measurement noise. Specifically, we consider two cases. In the first this covariance is fixed but unknown, and in the second this covariance is slowly-varying. For our tests, we only require knowledge of a set within which the covariance lies. Furthermore, we connect this problem to that of algorithmic fairness and the nascent field of fair hypothesis testing, and we show that our tests satisfy some notions of fairness. Finally, we exhibit the efficacy of our tests on empirical examples chosen to reflect values observed in a standard simulation model of autonomous vehicles.