Replay attack detection in a multi agent system using stability analysis and loss effective watermarking

In this paper the problem of detecting replay attack in a homogeneous multi agent system is addressed. Information exchange among the agents is under network topology and each agent is controlled to satisfy both local and global objectives. A local estimator and an anomaly detector are designed for each agent. Under replay attack to a part of network, we provide conditions on the stability of the under attack system in which, the attack cannot be detected by none of the agents. Next, a detection method is proposed which is based on using a watermarked control strategy, in which watermarking signal is shared among the agents through the network. Nevertheless, since this exogenous watermarking signal affects the performance of the controlled system, an optimization problem is introduced to find a watermarking signal with minimum loss effect.