Optimal symmetric Tardos traitor tracing schemes

TL;DR

This paper presents an optimized symmetric Tardos traitor tracing scheme that significantly reduces code length, approaching theoretical limits and outperforming previous methods in efficiency for large coalitions.

Contribution

It combines existing symmetric accusation functions with improved analysis to produce shorter codes, achieving near-optimal asymptotic codelengths for traitor tracing.

Findings

Codes up to 4 times shorter than previous schemes

Achieves asymptotic optimal codelengths for Tardos distribution

Reduces code length to about 4.93% of original Tardos lengths for large coalitions

Abstract

For the Tardos traitor tracing scheme, we show that by combining the symbol-symmetric accusation function of Skoric et al. with the improved analysis of Blayer and Tassa we get further improvements. Our construction gives codes that are up to 4 times shorter than Blayer and Tassa's, and up to 2 times shorter than the codes from Skoric et al. Asymptotically, we achieve the theoretical optimal codelength for Tardos' distribution function and the symmetric score function. For large coalitions, our codelengths are asymptotically about 4.93% of Tardos' original codelengths, which also improves upon results from Nuida et al.