Efficient multicast key management for stateless receivers

In a multicast communication system, group members possess a common group key and communicate using the key. For the communication between group members the group key must be managed securely and efficiently. Especially in a dynamic and large group the efficiency of the group key management is critical since the size of deleted or added members may be quite large. Most schemes proposed in the literature implicitly assume that members is constantly on-line, which is not realizable in many receiving devices. In the paper, we propose a hierarchical binary tree-based key management scheme for a dynamic large group with one group controller(GC), especially well suitable to stateless receivers, who do not update their state from session to session. In our scheme, all re-keying messages except for unicast of a individual key are transmitted without any encryption, all computation needed for re-keying is O(log₂ n) applications of one-way hash function and XOR operation, and all information needed for re-keying is in the current blinded factors and the initial information. The proposed scheme provides both backward and forward secrecy. If a bulletin board is used, each member can compute all needed keys without any re-keying messages.