Mobile Self-organizing Network Key Management System

Mobile Ad hoc Networks (MANETs) are composed of mobile nodes (MN), which can communicates with each other and moves freely in the network. A route may be constituted by several hops of wirless links between the nodes, without any surports of infrastructure. Each MN is not only a communication terminal, but also a router in the network. Without any aid of infrastructure, an effiecent and dynamic communication system can provide convenient communication services freely, especially in emergency, disaster and military environment.In this paper, we focused on the group key management in MANET. The MANET group key management technology is different from those in the traditional networks because of the decentralized, freely mobility, dynamic topologic and limited energy of the MANET. We presented a new topologic based group key management architecture combine the key management with the optimized topologic algorithm. We did theoretical and NS2 simulation work on optimization of both the group key management and topologic algorithm. The main contributions of this thesis are as follow:1. Brifly introduced the research work about the group key management. There are three types of group key management scheme in traditional networks:centralized contributory and distributed. The computation capability and the communication bandwith of the MANET nodes are vary. We develop a contributory key agreement scheme to setup the MANET group which achieves a smaller latency for group key generation than existing schemes. We then address the latency needed to rekey the group during member joins and departures. A protocol that determines the location to place a joining member is presented that considers the time needed for releying the joining member as well as the effect the joining member has upon the departure times of the other group members. Simulations are presented that compare our algorithms with existing schemes for different group size, as well as different user joins rates.2. Generally described the MANET virtual backbone technology, introduced several main MANET CDS algorithms, which are the basic for the hierarchical MANET group key management.3. Researched and developed a novel two layered group key management architecture for the popular two layered MANET, which contained gateway layer and non-gateway layer. The scheme combines distributed group key management scheme for gateway layer and the centralized key management scheme for non-gateway layer. It is shown that the communication cost of the key updating was optimized when the non-gateway nodes were averagely located under each gateway node. The re-keying messages will be reduced while the number of gateway nodes decrease.4. Studied three layered key management schemes for MANET with three layered virtual infrastructure. It is shown that reducing the quantity of the gateway nodes will optimize the communication cost of the re-keying procedure; the minimum communication cost can be achieved when the lower layer nodes locate evenly in each group in the centralized key management schemes; when the numbers of the gateway nodes is kept in a small scope, the DCC scheme should be more suitable for the three layered MANET than the DDC scheme. The MANET cluster protocol is improved by these conlusions. The key management communication cost will be reduced in the improved MANET virtual infrastructure.5. Optimiazed the group key tree in MANET key management scheme. We optimize the re-keying procedure in contributory group agreement scheme using the massage transifer hops instead of the broadcase meaasges. The simulation shows that this scheme is more suitable for the MANET than the existing other schemes.