Traitor Tracing for Subscription-Based Systems

In this paper we study the traitor tracing problem, which originates in attempting to combat piracy of copyrighted materials. When a pirated copy of the material is observed, a traitor tracing scheme should allow to identify at least one of the real subscribers (traitors) who participate in the construction of a pirated copy. In this paper, we focus on the pay-per-view type of subscription-based scenarios, in which materials are divided into multiple segments and each segment has multiple variations. We present a systematic way to assign the variations for each segment and for each subscriber using an error-correcting code. We give sufficient conditions for a code to be able to trace at least a traitor when faced with a coalition of m traitors. We also prove that these sufficient conditions are also necessary when the code is an MDS code.