Dynamic traitor tracing

Traitor tracing schemes were introduced so as to combat the typical piracy scenario whereby pirate decoders (or access control smart-cards) are manufactured and sold by pirates to illegal subscribers. Those traitor tracing schemes, however, are ineffective for the currently less common scenario where a pirate publishes the periodical access control keys on the Internet or, alternatively, simply rebroadcasts the content via an independent pirate network. This new piracy scenario may become especially attractive (to pirates) in the context of broadband multicast over the Internet. In this paper we consider the consequences of this type of piracy and offer countermeasures. We introduce the concept of dynamic traitor tracing which is a practical and efficient tool to combat this type of piracy. We also consider the static watermarking problem, presented by Boneh and Shaw, and derive bounds on the performance parameters of the “natural majority algorithm"”.