Title: Dynamic Watermarking for General LTI Systems,
Abstract: Detecting attacks in control systems is an important aspect of designing
secure and resilient control systems. Recently, a dynamic watermarking approach
was proposed for detecting malicious sensor attacks for SISO LTI systems with
partial state observations and MIMO LTI systems with a full rank input matrix
and full state observations; however, these previous approaches cannot be
applied to general LTI systems that are MIMO and have partial state
observations. This paper designs a dynamic watermarking approach for detecting
malicious sensor attacks for general LTI systems, and we provide a new set of
asymptotic and statistical tests. We prove these tests can detect attacks that
follow a specified attack model (more general than replay attacks), and we also
show that these tests simplify to existing tests when the system is SISO or has
full rank input matrix and full state observations. The benefit of our approach
is demonstrated with a simulation analysis of detecting sensor attacks in
autonomous vehicles. Our approach can distinguish between sensor attacks and
wind disturbance (through an internal model principle framework), whereas
improperly designed tests cannot distinguish between sensor attacks and wind
disturbance.