Secure Multicast Group Key Management Algorithm

More and more group-oriented applications are emerging with the evolution of the Internet. To efficiently utilize the network resources, multicast is adopted for these applications rather than unicast. Inevitably, multicast suffers from the similar security threats like unicast transmissions. However, the security mechanisms in unicast can not be directly applied to multicast. In this situation, secure multicast, which supplies multicast with security mechanisms, is becoming a hot research spot on network. Secure multicast uses a traffic encryption key shared by all group users to assure the communication confidentiality. As the core of efficient encryption, the group key management which deals with the management and distribution of the key materials is one of the key techniques in secure multicast.The research works presented in this dissertation mainly focus on improving the performance of the group key management in secure multicast.First of all, this dissertation extensively studied the group key management algorithms based on key tree in secure multicast. The key tree based group key management algorithms are widely used in secure multicast. The group key updating performance depends mainly on the key tree structure, so this dissertation focused on the key tree structure based on member updating probabilities. Several useful conclusions about key tree structure were obtained. Moreover, the degree of internal non-root nodes can be 2 or 3.Secondly, the conclusions of optimal key tree structure and the theory of dynamic programming were adopted in this dissertation to design an optimal key tree structure algorithm. The experiments have proved that the key tree structure achieved in this way had a better performance compared with other algorithms of the same kind.Moreover, the unbalanced key tree problem was considered. When the key tree is unbalanced, the performance of the group key management algorithm decreases significantly. Because the unbalanced degree is hard to define, in this dissertation the external path length was used to measure the average updating cost of a key tree. Therefore, the unbalanced a key tree was well depicted.To keep the key tree balanced, a new path shuffling algorithm was proposed in this dissertation to update the group key. This algorithm can decompose the balancing...