Security and robustness constraints for spread-spectrum Tardos fingerprinting

Abstract

This paper presents a practical analysis of the impact of robustness and security on Tardos' collusion-secure fingerprinting codes using spread-spectrum watermarking modulations. In this framework, we assume that the coalition has to face an embedding scheme of given security level and consequently has to suffer a probability of wrongly estimating their embedded symbols. We recall the Worst Case Attack associated to this probability, e.g. the optimal attack which minimises the mutual information between the sequence of a colluder and the pirated one. For a given achievable rate of the Tardos' fingerprinting model, we compare the Improved SpreadSpectrum embedding versus a new secure embedding (called ρ-Circular Watermarking) considering the AWGN channel. We show that secure embeddings are more immune to decoding errors than non-secure ones while keeping the same fingerprinting capacity.

Impacts of Watermarking Security on Tardos-Based Fingerprinting

“…The last important contribution of the article is that watermark security attacks can outperform AWGN attacks even when the estimation error rate is big. This work is an extension of the work presented in [21], where the ǫ-WCA was introduced, and takes into account the interplay between fingerprinting constraints (accusation performance) and watermarking constraints (security and robustness).…”