A dynamic encryption–decryption scheme for replay attack detection in cyber–physical systems

This paper deals with the replay attack detection problem for a class of cyber–physical systems. A dynamic encryption–decryption scheme is proposed with the purpose of detecting the replay attacks launched by the malicious adversary. First, a new attack model is established to describe the periodic replay attacks that are generated by making use of a series of recorded past measurements. Then, the stealthiness is discussed for the proposed replay attack scheme against the χ2 detector. Subsequently, on basis of the established model, a dynamic encryption–decryption scheme is developed without sacrificing any system performance, guaranteeing 100% detection probability in the occurrence of attacks. Finally, a simulation example is provided to firstly verify the stealthiness of the proposed replay attack and secondly demonstrate the effectiveness of the exploited dynamic encryption–decryption detection algorithm.