Scalable key management for secure multicast communication in the mobile environment

• Authors: Jiannong Cao;Lin Liao;Guojun Wang
• Venue: Pervasive and Mobile Computing
• Year: 2006

The proliferation of the Internet computing and mobile computing technologies gives rise to the growth of mobile Internet applications. There are increasing demands on secure multicast services in the mobile Internet environment. An important issue in secure group communication is key management, which is concerned with distributing and updating the keys for encrypting the multicast messages in a group of mobile users. The challenges in designing secure and scalable key management protocols are dynamic updates of the key caused by frequent moves, joining and leaving of group members and the large size of a group for mobile Internet applications. In this paper, we propose a scalable and hierarchical key management (SHKM) protocol in the mobile Internet. In order to address the scalability issue, SHKM divides the group of users into different subgroups, where each subgroup uses its own key. Different from existing decentralized schemes, the subgroups in the SHKM protocol are organized into a hierarchical structure with different priorities. Each pair of parent-child subgroups is given a related factor based on their subgroup keys. The trusted third-party authority is responsible for computing the parameters. Based on these and some public parameters, users belonging to a higher-priority subgroup have the right and are capable to deduce the keys of lower-priority subgroups but the reverse operation is not allowed. Because the subgroup itself can perform the derivation, the number of re-keying messages for updating the global key management system across the subgroup boundaries can be significantly reduced. We compare the proposed protocol with some existing protocols, and conclude that the number of re-keying messages in our proposed protocol is the least among all these protocols.