Secure group communications using key graphs
IEEE/ACM Transactions on Networking (TON)
Batch rekeying for secure group communications
Proceedings of the 10th international conference on World Wide Web
Algorithms for dynamic multicast key distribution trees
Proceedings of the twenty-second annual symposium on Principles of distributed computing
A survey of key management for secure group communication
ACM Computing Surveys (CSUR)
Optimal Tree Structures for Group Key Management with Batch Updates
SIAM Journal on Discrete Mathematics
Approximately optimal trees for group key management with batch updates
TAMC'07 Proceedings of the 4th international conference on Theory and applications of models of computation
Optimal tree structure for key management of simultaneous join/leave in secure multicast
MILCOM'03 Proceedings of the 2003 IEEE conference on Military communications - Volume II
Optimal Tree Structures for Group Key Tree Management Considering Insertion and Deletion Cost
COCOON '08 Proceedings of the 14th annual international conference on Computing and Combinatorics
Optimal tree structures for group key tree management considering insertion and deletion cost
Theoretical Computer Science
Optimal tree structure with loyal users and batch updates
Journal of Combinatorial Optimization
Optimal key tree structure for two-user replacement and deletion problems
Journal of Combinatorial Optimization
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Multicast and broadcast are efficient ways to deliver messages to a group of recipients in a network. Due to the growing security concerns in various applications, messages are often encrypted with a secret group key. The key tree model which has been widely adopted maintains a set of keys in a tree structure so that in case of group member change, the group key can be updated in a secure and efficient way. In this paper, we focus on the updating cost incurred by member deletions. To implement a sequence of member deletions in any key tree, a certain number of encrypted messages need to be broadcast to accomplish the updates. Our goal is to identify the best key tree which can minimize the worst-case deletion cost (i.e., the amortized cost over n member deletions). We prove that there is an optimal tree in which each internal node has at most five children and each internal node with at least one non-leaf child has exactly three children. Based on these characterizations, we present a dynamic programming algorithm that computes an optimal key tree in O(n^2) time.