Efficient distributed group key agreement scheme

An efficient distributed group key agreement scheme was developed to improve the poor scalability of most existing distributed group key agreement schemes which require each member to maintain the whole key tree structure. In this scheme, each group member maintains only a key tree branch including five element sets, which reduces the storage and communication costs of each member. A distributed tree balancing algorithm is used to keep the whole key tree as balanced as possible for rekeying efficiency, even though each member has only partial information for the whole key tree. Test results demonstrate that the scheme significantly reduces the storage and communication costs for each member for maintaining the key tree, thus, the scheme can be scaled to large groups.