Two-Way Coding in Control Systems Under Injection Attacks: From Attack Detection to Attack Correction

TL;DR

This paper introduces two-way coding into networked control systems to distort attacker perception, enabling improved attack detection and correction, especially against zero-dynamics attacks, under certain stabilizability conditions.

Contribution

It applies two-way coding from communication theory to control systems, providing a novel approach for attack detection and correction in networked feedback control.

Findings

Two-way coding distorts attacker perception.

Zero-dynamics attacks become detectable with two-way coding.

Attack effects can be corrected under stabilizability assumptions.

Abstract

In this paper, we introduce the method of two-way coding, a concept originating in communication theory characterizing coding schemes for two-way channels, into (networked) feedback control systems under injection attacks. We first show that the presence of two-way coding can distort the perspective of the attacker on the control system. In general, the distorted viewpoint on the attacker side as a consequence of two-way coding will facilitate detecting the attacks, or restricting what the attacker can do, or even correcting the attack effect. In the particular case of zero-dynamics attacks, if the attacks are to be designed according to the original plant, then they will be easily detected; while if the attacks are designed with respect to the equivalent plant as viewed by the attacker, then under the additional assumption that the plant is stabilizable by static output feedback, the attack effect may be corrected in steady state.