An efficient structure for LKH key tree on secure multicast communications

In order to communicate in cipher over IP multi-cast, each of joining and leaving participants causes renewing keys. Moreover, the number of renewed keys depends on the key management system. LKH, one of the key management systems, uses a tree structure to manage keys to share with participants. Every node of the tree is given a key, and each leaf of the tree is corresponding to a participant. If all members are handled equally, by using a balanced binary tree, the average number of renewed keys per join and leave is estimated at ⌈log₂ n ⌉, where n denotes the number of participants. In this study, we introduce a scenario that the key management system can distinguish between inconstant members and stable members, instead of handling members equally. Under this scenario, our system improves the number of renewing keys efficiently by considering another tree structure against the balanced binary tree structure.