Design of Multi-Sine Watermark using Power Spectral Analysis for Replay Attack Detection

Abstract

Design of multi-sine watermark using power spectral analysis for replay attack detection Sunitha George Replay attacks are a critical security concern in cyber-physical systems (CPS), where adversaries record legitimate data transmissions and maliciously retransmit them later to disrupt normal system operations. These attacks are particularly dangerous because they often replay legitimate data, making them difficult to detect using traditional intrusion detection systems. As CPS continue to integrate deeper into critical infrastructure such as power systems, industrial automation, and transportation networks, the need for better safety measures becomes increasingly urgent. One promising line of defense involves watermarking techniques, in particular, using multi-sine watermarks with switching frequencies. This thesis studies the problem of choosing the parameters of multi-sine watermarks to achieve replay attack detection with desired level of confidence. The proposed method is derived from a power spectral analysis of the output of the plant in both normal (no attack) and during attack operation. A flow control process involving a tank is utilized as an illustrative example. Through this example, the effectiveness of the proposed method is validated, showing its capability to design a watermark that can successfully detect replay attacks and thus enhance the security of the control system