Abstract
Multicast streaming service is one of the prospective killer applications in Internet. Secure group communication, which provides confidentiality, authenticity, and integrity of messages delivered between group members, will become an interesting and critical issue in multimedia delivery services in the near future. Several techniques have been proposed to solve this problem, among them, the key management problem is the most important one, which can maintain the group state dynamically and protect the improper access and unauthorized playback as well. There is a famous solution of the key management problem that uses key tree graph (WGL scheme). Although the WGL scheme solved the backward and forward secrecy problem, but the number of keys that WGL scheme needs is too large. This results a large storage requirement and high computation and communication costs causing by membership changes. In this thesis, a novel method based upon the quorum secret sharing scheme to solve the key management problem is presented. In addition, a corresponding quorum-secret-sharing based protocol that can fulfill the backward and forward secrecies is also proposed. The theoretical analysis shows our method is better than WGL scheme in the storage requirement and the computation cost as well as the communication cost for JOIN. For the LEAVE operation, our method is worse than WGL, however, we address that we may use parallel computation or cluster technique to improve it because the level of distribution and parallel of our method are higher than WGL scheme.