Affiliations: Department of Computer Science, College of Computers and Information Technology, Taif University, Taif, Kingdom of Saudi Arabia. E-mail: elzoghdy@yahoo.com | Department of Computer Engineering, College of Computers and Information Technology, Taif University, Taif, Kingdom of Saudi Arabia. E-mail: yaser.asem@gmail.com
Note: [] Corresponding author. Said Fathy El-Zoghdy, E-mail: elzoghdy@yahoo.com.
Abstract: The Internet multicast capabilities have been used in enormous number of groups through the Internet. However, IP multicast does not deploy any mechanisms to secure the multicast messages in these groups. A lot of research efforts have been done to secure multicast messages. The idea behind the multicast security is to share a symmetric key between group members to encrypt/decrypt the multicast messages and to change this key after any membership change. The main re-keying problem is how to exchange the new group key between the group members in a scalable and secure way. In this paper we present a new multicast re-keying approach that is based on dividing the whole group into smaller subgroups. Each subgroup in turn is organized in a logical key hierarchy tree, and each subgroup member has the inverse key values of the other members in his subgroup in order to make the subgroup re-keying in a scalable and secure way. This decomposition, the proposed approach, which is named as Key Inverse Re-keying (KIR), reduces the multicast complexity from O(n) to O(log 2m) where n is the total number of the whole group members and m is the number of members in each subgroup. The performance of KIR is compared with that of other group re-keying approaches to prove its effectiveness. The comparison is undertaken according to the computational overhead, communication overhead, storage overhead, and message size. The results show that KIR enhances the group performance in terms of computational overhead and communication overhead especially at the leave operation which represents a big problem for most of the previous group re-keying protocols.
Keywords: Multicast group re-keying, multicast security, key inverse, key tree, logical key hierarchy, KIR
