Dynamic Traitor Tracing Schemes, Revisited

We revisit recent results from the area of collusion-resistant traitor tracing, and show how they can be combined and im-proved to obtain more efficient dynamic traitor tracing schemes. In particular, we show how the dynamic Tardos scheme of Laarhoven et al. can be combined with the optimized score functions of Oosterwijk et al. to trace coalitions much faster. If the attack strategy is known, in many cases the order of the code length goes down from quadratic to linear in the number of colluders, while if the attack is not known, we show how the interleaving defense may be used to catch all colluders about twice as fast as in the dynamic Tardos scheme. Some of these results also apply to the static traitor tracing setting where the attack strategy is known in advance, and to group testing.