Efficient key distribution schemes for secure media delivery in Pay-TV systems

Abstract—To provide secure media delivery in pay-TV systems, a large number of messages are exchanged for key updates in the conventional key distribution schemes. This is inefficient and costly when the client side (set-top box) uses a smart card with limited computing power. In this paper, we present three key distribution schemes for channel protection and secure media de-livery in pay-TV systems. With the proposed schemes, encryption keys of the subscribed programs can be efficiently and securely distributed to the authorized subscribers. Only one message is needed to renew key in the key distribution schemes for subscrip-tion channel protection. In addition, we use simpler computation functions, including one-way hash function and exclusive-OR op-eration, for key updates to reduce the computation cost. With our key distribution schemes, only authorized subscribers can watch the subscribed programs correctly. Unauthorized subscribers have no information to retrieve the correct programs over the networks. Thus, service providers can charge their subscribers according to their subscriptions, and the illegal access of the media and video programs from networks can be prevented, based on the proposed schemes. Index Terms—Channel protection, conditional access system, key distribution scheme, secure media delivery. I