Abstract: STR group key management protocol can simplify key updating for its unbalanced binary-tree structure and decrease communication cost by increasing computing cost in group key management. A hybrid group key management scheme based on STR unbalanced tree was presented. It significantly decreases computation cost, and increases key updating efficiency, while maintaining the low-communication cost feature of STR protocol at the same time.

Key words: group key management, key updating efficiency, computing cost, communication cost, security