Solving a Centralized Dynamic Group Key Management Problem by an Optimization Approach

Thi Tuyet Trinh Nguyen, Hoang Phuc Hau Luu, Hoai An Le Thi

Abstract: In centralized key management schemes, a single trusted entity called a Key Server is employed to manage the group key and other supporting keys of the entire group. This management mechanism usually employs a binary tree based structure. In dynamic multicast communication, members may join/leave the group at any time, which requires a certain cost to update the binary key tree. This paper addresses an important problem in centralized dynamic group key management. It consists in finding a set of leaf nodes in a binary key tree to insert new members while minimizing the insertion cost. Since the inserting cost is proportional to the distance from the root to the selected leaf node, the balance of the tree plays an important role in dynamic group key management. Therefore, our proposed approach also considers the balance of the tree after insertion. The two mentioned important objectives are combined into a unified optimization framework.