Abstract: Group keys have been applied to mobile Ad Hoc networks (MANET) to assure secure communication. This paper presents key management architectures for MANET with two-layered and three-layered virtual infrastructure. The analysis showed that (1) the distributed-centralized architecture is more suitable for two-layered MANET, when the leaf nodes averagely located under each gateway node, the rekey messages would be optimized; (2) when the number of the first layer gateway nodes keep in a small scale, the two-distributed-one-centralized key management architecture is more suitable for three-layered MANET. (3) Based on the same condition, the three layered key management architecture will achieve less communication cost comparing with the two layered ones. We optimized the MANET virtual infrastructure protocol with these conditions. The simulation results showed that it can improve the communication efficiency.

Key words: MANET virtual infrastructure, Key Management architecture, Three-layered key management scheme, Two layered key management scheme