Group-oriented channel protection for mobile devices in digital multimedia broadcasting

In 2004, Huang et al. proposed a new key distribution scheme for media delivery in Pay-TV Systems based on a four-level key hierarchy. A three-key distribution scheme is proposed in Huang et al.'s paper. They use an exclusive-OR operation and a one-way hash function for key distribution in order to reduce the computational cost. One of the key distribution schemes for subscription channel protection, the group oriented key distribution scheme, however, is inefficient for the digital multimedia broadcasting (DMB) service in resource-limited mobile phones. In this paper, we show that Huang et al.'s scheme is inefficient regarding subscription channel protection. As a result, we propose an improved scheme to reduce this inefficiency by applying a two-level key hierarchy method for a resource limited device, such as the DMB service in mobile phones.