Secure networked control systems against replay attacks without injecting authentication noise

This paper studies detection of replay attacks on networked control systems, assuming that the actuation and sensing signals are transmitted over an additive white Gaussian noise channel. It explores the use of the spectral estimation technique to detect the presence of a replay attack without injecting authentication noise to the control signal at the plant input. Our proposed detection method is applicable to networked feedback systems equipped with stable controllers and designed with classical and modern control system techniques. A numerical example from the literature is used to illustrate the detection results for replay attacks on networked control systems.