A∗-based key tree structure generation for group key management in wireless sensor networks

The application of wireless sensor networks to areas such as combat field surveillance, terrorist tracking and highway traffic monitoring requires secure communication among the sensor nodes within the networks. Logical key hierarchy (LKH) is a tree-based key management model which provides secure group communication. When a sensor node is added or evicted from the communication group, LKH updates the group key in order to ensure the security of the communications. In order to efficiently update the group key, we propose an A∗-based key tree structure, an extension to LKH, that reduces the number of re-key messages by considering the addition and eviction ratios of the history data. For the generation of the proposed key tree structure the A∗ algorithm is applied, in which the branching factor at each level can take on different value. The experimental results demonstrate the efficiency of the proposed key tree structure against the existing key tree structures of fixed branching factors.