Design of efficient ID-based group key agreement protocol suited for Pay-TV application

Pay-TV application is one of the challenging home appliances where a TV program is delivered to a group of customers. The broadcaster of the Pay-TV system needs to assure that only legitimate subscribers/customers can watch the subscribed TV program. To deliver a TV program confidentially to its subscribers, the broadcaster may encrypt the program by a group key shared by all subscribers. Thus the Pay-TV system often requires a group key establishment protocol to establish a symmetric key among all the subscribers subscribing for a particular program. The group key agreement protocol for Pay-TV system presented so far are requires bilinear pairing computations which creates a big overhead for subscribers specially in wireless environment. A protocol is suitable for Pay-TV system only when most of the computational load are shifted to the broadcaster than the subscribers because the subscribers may have less computational resources as compared to the broadcaster. The present paper proposes an ID-based group key agreement protocol suitable for the Pay-TV system without using bilinear pairing. The proposed protocol also have efficient join and leave procedures to allow dynamic subscriptions with forward and backward secrecy. Moreover, the security of the proposed protocol is justified with respect to the necessary security attributes. Finally the performance of proposed protocol has been compared with some other existing protocols which shows that the proposed protocol has comparable communication and computation cost with zero pairing computation.