Hybrid Design of Multiplicative Watermarking for Defense Against Malicious Parameter Identification

TL;DR

This paper introduces a hybrid multiplicative watermarking scheme that periodically updates watermark parameters to enhance security against malicious parameter identification, while maintaining system stability.

Contribution

The paper proposes a novel hybrid multiplicative watermarking method with dynamic parameter updates based on PWA hybrid systems, improving resistance to eavesdroppers.

Findings

The scheme preserves stability of the closed-loop system.

It increases the difficulty for eavesdroppers to reconstruct watermark parameters.

Theoretical analysis confirms robustness against malicious identification.

Abstract

Watermarking is a promising active diagnosis technique for detection of highly sophisticated attacks, but is vulnerable to malicious agents that use eavesdropped data to identify and then remove or replicate the watermark. In this work, we propose a hybrid multiplicative watermarking (HMWM) scheme, where the watermark parameters are periodically updated, following the dynamics of the unobservable states of specifically designed piecewise affine (PWA) hybrid systems. We provide a theoretical analysis of the effects of this scheme on the closed-loop performance, and prove that stability properties are preserved. Additionally, we show that the proposed approach makes it difficult for an eavesdropper to reconstruct the watermarking parameters, both in terms of the associated computational complexity and from a systems theoretic perspective.