Traitor Tracing And Revocation Mechanisms With Privacy Preserving

Content distribution systems are vulnerable to the attack ofrebroadcasting: pirate publishes the content or the decoding key inviolation of the licensing agreement. Sometimes several traitors colludetogether producing a separate decoding key and rebroadcast to the pirate.Broadcast encryption deals with methods to efficiently broadcastinformation to a dynamically changing group of users who are allowed toreceive the data. Tracing Mechanism enables the efficient tracing ofleakage, specifically, the source of keys used by illegal devices, such aspirate decoders or clones.We argue that privacy is another important feature in digital rightsmanagement technologies, and the proper balance between DRM and userprivacy is an important question in its own right. Our scheme adds thisimportant privacy-preserving feature into the existing content distributionsystem and with the help of a trusted third party it can efficiently trace andrevoke the pirate users while still preserves the privacy of honest users.This paper proposed two constructions. The first one is based on e-cash,which is constructed by blind signatures. It requires a trusted third party(TTP). The second construction is based on anonymous credential system,which does not rely on the TTP. Both of the constructions are based onDDH problem.