  In remote estimation of cyber-physical systems (CPSs), sensor measurements
transmitted through network may be attacked by adversaries, leading to leakage
risk of privacy (e.g., the system state), and/or failure of the remote
estimator. To deal with this problem, a chaotic masking protocol is proposed in
this paper to secure the sensor measurements transmission. In detail, at the
plant side, a chaotic dynamic system is deployed to encode the sensor
measurement, and at the estimator side, an estimator estimates both states of
the physical plant and the chaotic system. With this protocol, no additional
secure communication links is needed for synchronization, and the masking
effect can be perfectly removed when the estimator is in steady state.
Furthermore, this masking protocol can deal with multiple types of attacks,
i.e., eavesdropping attack, replay attack, and stealthy false data injection
attack.
