Date Added: May 2012
The vast majority of today's critical infrastructure is supported by numerous feedback control loops and an attack on these control loops can have disastrous consequences. This is a major concern since modern control systems are becoming large and decentralized and thus more vulnerable to attacks. This paper is concerned with the estimation and control of linear systems when some of the sensors or actuators are corrupted by an attacker. In the first part, the authors look at the estimation problem where they characterize the resilience of a system to attacks and study the possibility of increasing its resilience by a change of parameters. They then propose an efficient algorithm to estimate the state despite the attacks and they characterize its performance.