Stochastic coding detection scheme in cyber-physical systems against replay attack

In this paper, the security problems in cyber-physical systems (CPSs) against replay attack are considered. With replay attacks, attacker records and covers the transmitted data between the senders and receivers of the sensors. In order to achieve the detection objective for malicious replay attacks, the stochastic coding scheme is proposed to make the CPSs generate covariance differences between the normal and compromised data. Different from the existing results, this method detects the replay attack without sacrificing any system performances in normal systems. Based on the coding scheme, two types of detectors are further designed to detect the covariance changes in residual and output, respectively. Moreover, the output-based detector has more low-computing solution process than the residual-based one. Finally, a practical example is proposed to demonstrate the superiority of the stochastic coding scheme. (C) 2019 Elsevier Inc. All rights reserved.