Dynamic Traitor Tracing for Arbitrary Alphabets: Divide and Conquer
This work addresses the need for efficient traitor tracing in digital content protection, offering incremental improvements by extending existing methods to arbitrary alphabets.
The paper tackles the problem of constructing collusion-resistant dynamic traitor tracing schemes with larger alphabets by proposing a generic divide-and-conquer approach that reduces codelength by a factor equal to half the alphabet size, bridging the gap between low-bandwidth and high-bandwidth schemes.
We give a generic divide-and-conquer approach for constructing collusion-resistant probabilistic dynamic traitor tracing schemes with larger alphabets from schemes with smaller alphabets. This construction offers a linear tradeoff between the alphabet size and the codelength. In particular, we show that applying our results to the binary dynamic Tardos scheme of Laarhoven et al. leads to schemes that are shorter by a factor equal to half the alphabet size. Asymptotically, these codelengths correspond, up to a constant factor, to the fingerprinting capacity for static probabilistic schemes. This gives a hierarchy of probabilistic dynamic traitor tracing schemes, and bridges the gap between the low bandwidth, high codelength scheme of Laarhoven et al. and the high bandwidth, low codelength scheme of Fiat and Tassa.