Stealthy Linear Deception Attacks against Kalman Filtering with Partially Secured Measurements

In this paper, we investigate an optimal strategy for malicious agents to compromise remote state estimators where only a portion of the transmitted packets is secured. First, the analysis of the performance evolution and stealthiness properties of innovation-based linear attacks that can compromise unsafe transmission channels is provided. An optimal attack policy is then derived by numerically solving an optimization problem step by step. Different from the scenario where all links are vulnerable to cyber-attacks, the existence of secured channels poses a tighter stealthiness constraint and thus can significantly reduce the worst-case attack impact. Additionally, it is shown that the well-studied flipping-sign-attack in existing work cannot remain stealthy. Finally, a numerical example and comparative studies are included to verify the effectiveness of the proposed method.