  This paper addresses the problem of decentralized state-tracking in the
presence of sensor attacks. We consider a network of nodes where each node has
the objective of tracking the state of a linear dynamical system based on its
measurements and messages exchanged with neighboring nodes notwithstanding some
measurements being spoofed by an adversary. We propose a novel decentralized
attack-resilient state-tracking algorithm based on the simple observation that
a compressed version of all the network measurements suffices to reconstruct
the state. This motivates a 2-step solution to the decentralized secure
state-tracking problem: (1) each node tracks the compressed version of all the
network measurements, and (2) each node asymptotically reconstructs the state
from the output of step (1). We prove that, under mild technical assumptions,
our algorithm enables each node to track the state of the linear system and
thus solves the decentralized secure state-tracking problem.
