A simple XOR-based technique for distributing group key in secure multicasting

One approach to multicast group security is to have a group key shared by every group member. In this paper, we are interested in group key distribution and management. A new simple technique is introduced for key distribution to a large group based on the hierarchical key tree. The new technique uses bit XOR operation between keys to reduce the computation effort, and uses random byte patterns (BPs) to distribute the key material in the multicast message. The new technique has symmetric procedures for message construction by a key distribution center (KDC) when a member joins or leaves the group, which allows the generation of one rekey message that incorporates multiple delays of both joins and leaves. In addition to the substantial decrease in the computation effort, our technique decreases the required group member storage. Finally, a novel model for the key tree in a distributed KDC is introduced. The new model allows sending the rekey message by one KDC to the whole group and other peer KDCs without any increase in the delay or the number of sent messages. This is achieved by building and replicating an additional KDC key tree.