Efficient Methods for Integrating Traceability and Broadcast Encryption

In many applications for content distribution, broadcast channels are used to transmit information from a distribution center to a large set of users. Broadcast encryption schemes enable the center to prevent certain users from recovering the information that is broadcast in encrypted form, while traceability schemes enable the center to trace users who collude to produce pirate decoders. In this paper, we study general methods for integrating traceability and broadcasting capability. In particular, we present a method for adding any desired level of broadcasting capability to any traceability scheme and a method for adding any desired level of traceability to any broadcast encryption scheme. To support our general methods, we also present new constructions of broadcast encryption schemes which are close to optimal in terms of the total number keys required. Our new schemes are the first to be both maximally resilient and fully scalable.