Detector

Algorithm

Residual

Scheme (mathematics)

Cyber-physical system

Hash function

Statistics

Stochastic process

Computer security

Real-time computing

Theoretical computer science

Operating system

Telecommunications

Coding (social sciences)

Computer science

Computer network

Covariance

Mathematics

Mathematical analysis

Replay attack

Information Sciences

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.

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