A Flexible Category-Based Collusion-Resistant Key Management Scheme for Multicast
Claudiu Duma, Nahid Shahmehri, Patrick Lambrix · 2003
Current key management schemes for multicast provide either no resistance to collusion or perfect resistance to collusion. However, resistance to collusion is achieved at the expense of efficiency in terms of the number of transmissions and the number of keys that are used. We argue that applications may have certain assumptions regarding the users and their access to the multicast channel that may be used to provide a larger choice for balancing efficiency against resistance to collusion. Starting from a user categorization, based on the accessibility to the multicast channel, we formalize the collusion requirement. Different user categorizations give different degrees of collusion resistance and we show that the existing work has focused on special cases of user categorizations. Further, we propose and evaluate a flexible key management strategy for the general case where the accessibility relation defines the order of exclusion of the categories. The theoretical and experimental results show that our scheme has good performance regarding transmissions and keys per controller.