Detection for Controller-to-Actuator Replay Attack in Cyber-Physical Systems via Pseudo-Random Code

In this paper, we consider the detection problems of controller-to-actuator replay attacks in cyber-physical systems (CPSs). The replay attacks on controller-to-actuator channels can influence the dynamic property and even stability. For the detection task, we employ a pseudo-random signal to code those communication channels, and code-decode abnormalities are generated when replay attacks occur. The abnormalities can be modeled as an additional Gaussian signal in system dynamic. Then, an anomaly detector is designed with a new type, which combines the pseudo-random signal covariance, to detect the abnormalities caused by replay attack and pseudo-random code. As a result, we obtain an optimization problem to solve the threshold value of detector and the covariance of code signal. Finally, a numerical example is proposed to illustrate the effectiveness of the above conclusions.