Research Of Group Key Management For Ad Hoc Networks

Ad Hoc network, as a new type of wireless and multi-hop network, has been widely used because of its properties such as dispensing without network establishment, speedy buildup and so on. Simultaneously, the reliable trust relationship of nodes in the network does not existed, due to the unfixed nodes. Therefore, the network can be extremely vulnerable to attack. The constitution of group key management for Ad Hoc network is facing a great of challenges because of acentric characteristic, dynamic topology structure and so on.This thesis first discusses the development of Ad Hoc network and the status of network security, then analyzes and summarizes the security requirements and related theories for Ad Hoc network. The thesis focuses on the research of group key management for Ad Hoc network. The main contributions of the thesis include:This thesis analyzes the principles and structural features of three basal tree-based group key managements, and compares the communication and computation generated by each protocol when their members are adding in, leaving, merging or breaking up. The analysis and comparison results can show the adaptability of each tree-based group key management for Ad Hoc network. It provides the theory and technical reference for the further study in Ad Hoc networks.This thesis proposes a group key management scheme based on symmetric polynomial, which adapts existing work on STR (The Skinny Tree) that combines key trees with Diffie-Hellman group key exchange, by replacing expensive public key operations with relatively cheaper symmetric key operations. In this scheme, the modular exponentiations in key exchange are replaced by polynomial evaluations in Galois fields, thereby reducing the space and computation substantially. This thesis also discusses relationship establishment for nodes when structure changes. Compared with other group key managements based on polynomial, this scheme reduces the computation of producing group keys in the same security for Ad Hoc network, so that it has high expansibility.This thesis proposes an effective and secure multilayer group key management scheme, which achieves the production of the group keys and the building of communication channels by building multiple key chains. This scheme has several features, such as quantitative distribution according to original requests, safe and efficient generations of group keys and communication keys and so on. It is applicable to topological Ad Hoc network, in which the nodes have limited computational and memory resources.