Optimizing the tree structure in secure multicast key management

We study the issue of distributing cryptographic keys to a secure multicast group. The key management is focused on virtual tree-based schemes represented by the logical key hierarchy (LKH). We present the optimal key tree structure problem. Specifically, we address minimizing the computational overhead of the key server with analytical formulation and propose two new variations of LKH. The first one is based on hash functions while the second being an observably different approach of generating new keys based on existing ones. Both structures are investigated and optimized for the key server.