  Security of Distributed Parameter Cyber-Physical Systems (DPCPSs) is of
critical importance in the face of cyber-attack threats. Although security
aspects of Cyber-Physical Systems (CPSs) modelled by Ordinary differential
Equations (ODEs) have been extensively explored during the past decade,
security of DPCPSs has not received its due attention despite its
safety-critical nature. In this work, we explore the security aspects of DPCPSs
from a system theoretic viewpoint. Specifically, we focus on DPCPSs modelled by
linear parabolic Partial Differential Equations (PDEs) subject to cyber-attacks
in actuation channel. First, we explore the detectability of such attacks and
derive conditions for stealthy attacks. Next, we develop a design framework for
cyber-attack detection algorithms based on output injection observers. Such
attack detection algorithms explicitly consider stability, robustness and
attack sensitivity in their design. Finally, theoretical analysis and
simulation studies are performed to illustrate the effectiveness of the
proposed approach.
