A Switching Multiplicative Watermarking Scheme for Detection of Stealthy Cyber-Attacks

• Published in: IEEE transactions on automatic control Vol. 66; no. 6; pp. 2558 - 2573
• Main Authors: Ferrari, Riccardo M. G., Teixeira, Andre M. H.
• Format: Journal Article
• Language: English
• Published: New York IEEE 01.06.2021; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Atmospheric measurements; Authentication; Cryptography; Cybersecurity; Design parameters; Digital filters; equalizers; Hybrid systems; intrusion detection; Particle measurements; Robustness (mathematics); security; Switches; Switching; Watermarking
• ISSN: 0018-9286; 1558-2523; 1558-2523
• DOI: 10.1109/TAC.2020.3013850

This article addresses the detection of stealthy attacks on sensor measurements. Inspired in authentication schemes with weak cryptographic guarantees, we propose a watermarking approach to validate the data and its source. In particular, we propose a multiplicative scheme, where the sensor outputs are watermarked by a bank of filters, then transmitted through the possibly unsecured communication network. The original measurement data are finally reconstructed by a watermark remover. To allow the detection of replay attacks, the watermarking filters are devised as hybrid switching systems, whose parameters are assumed to be unknown to the adversary. Design rules are provided, guaranteeing that the nominal closed-loop performance is not deteriorated by the watermarking scheme and ensuring robust stability with mismatched filter parameters. Moreover, we design a switching protocol with no communication overhead to allow the watermarking filters to synchronously update their parameters. The detectability properties of cyber-attacks are analyzed, and the results are illustrated through numerical examples for replay and data injection attacks.