Balanced key tree management for multi‐privileged groups using (N, T) policy

Abstract

ABSTRACTMany internet applications are based on group communication model. For secure group communication scenario, key management is an important issue. In a hierarchical architecture, key trees are used. When users join or leave a key tree, all the ancestor nodes in the leave path till root gets affected. It encroaches threat to forward secrecy as well as backward secrecy. This poses a need for rekeying whenever users join or leave. Periodic batch rekeying is a process where the key server waits until the rekey interval is elapsed and does the rekeying process. Nevertheless, there are many key management schemes; there is still research fostering in key management in group communication for multi‐privileged users, where the users of the group have access to multiple resources, unlike the traditional case with single resource. This paper addresses batch user join or leave case in multi‐privileged environment. A variation of batch rekeying is introduced by using min(N, T) policy so that the users need not wait until the rekey interval is reached and the probabilistic analysis based on it are provided. It also discusses about the improvement in terms of number of rekeying done and provides a balanced tree when multiple users join/leave. Copyright © 2011 John Wiley & Sons, Ltd.