Sequential traitor tracing

We consider a new type of traitor tracing scheme, called sequential traitor tracing, that protects against rebroadcasting of decrypted content. Sequential traceability (TA) schemes trace all up to c traitors and remove the shortcomings of dynamic tracing schemes. We give two general constructions and show the relationship between c-TA codes and sequential tracing schemes.

I. Introduction

Traitor tracing is studied in different contexts. In broadcast encryption [1], the information is broadcasted to a set of authorized receivers. Each receiver has a decoder with a unique key that allows him to decrypt the encrypted broadcast. Traitor tracing schemes protect against a pirate decoder that is constructed by a group of colluders that use their key information to illegally decrypt the broadcast. Traitor tracing is also used in the context of data fingerprinting, where colluders use their copies of a digital object to construct a pirate copy of the object; again the aim is to trace one of the colluders.