An efficient scalable key management scheme for secure group communication

Several multicast key management schemes such as those proposed by Wallner et al and Wong et al are based on a multilevel, logical hierarchy (or tree) of key-encrypting keys. When used in conjunction with a reliable multicast infrastructure, this approach results in a highly efficient key update mechanism in which the number of multicast messages transmitted upon a membership update is proportional to the depth of the tree, which is logarithmic to the size of the secure multicast group. But this is based on the hypothesis that the tree is maintained in a balanced manner. This paper proposes a scalable rekeying scheme---link-tree structure for implementing secure group communication. Theoretical calculation and experimentation show that this scheme has better performance than the tree structure and the star structure, and at the same time still keep the link-tree structure balanced.