关键词: 密码学, 密钥管理, 通信约束, 优化, 不动点方程

Abstract: This paper studies the problem of designing a storage efficient secure multicast key management scheme based on
Hybrid One-way Function Tree（HOFT） for a prespecified rekey communication overhead.A hybrid tree scheme divides a group of N members into clusters of M members and assigns each cluster to one leaf node of a key tree.Using this scheme,this paper formulates a constrained optimization problem to minimize the centralized group controller storage in terms of the cluster size M,then converts the constrained optimization into a fixed point equation and derive the optimal cluster siz M that leads to the minimal storage overhead as O（N/logN）,when the key update communication constraint is given as O（logN）.The paper designs a algorithm that achieves minimal centralized group controller storage.

Key words: cryptography, key management, communication constraint, optimization, fixed-point equation