Efficient Multicast Key Management for Stateless Receivers

Abstract

In a multicast communication system, group members possess a common group key and communicate us ng the key. For the commun cat on 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 is 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 un cast of a nd vidual key are transm tted without any encryption, all computat on needed for re-keying is O( log₂ n) applications of one-way hash funct on and XOR operation, and all information needed for re-keying is in the current blinded factors and the initial informaton. The proposed scheme provides both backward and forward secrecy. If a bullet n board is used, each member can compute all needed keys without any re-keying messages.

This work was supported by grant No.R01-2001-000-00537-0(2002)from the Korea Science & Engineering Foundation.