The Research And Improvement Of Route Protocol's Security In Ad Hoc Network

With the rapid development of Ad Hoc network, its security issues become increasingly prominent. Due to limitation on wireless channel,dynamic topology, self-organization and node resources, Ad Hoc network is more vulnerable than traditional one. At present, secret key management,intrusion detection, enhanced cooperation and security routing protocol are the four methods commonly adopted in security assurance.This thesis comprehensively summarizes the security problems Ad Hoc network is facing and methods to security assurance, and studies profoundly the SAODV routing protocol. Adopting public-key encryption algorithms which costs more and has higher calculation complexity in verification, SAODV routing protocol is more resource-and-time consuming. It's discovered in the study of SAODV routing protocol that a node in the network will verify again when it receives message from the same mode in a very short period of time. The assumption that a legal node is likely to remaining legal node after a short period of time makes a lot redundancy during the process of verification. According to this, this thesis presents credibility mechanism: nodes build trust with other nodes in the network according to historical verification, and decide whether to verify according to credibility and probability, thus reducing the times of verification when nodes receive routing message, which saves network resources and decreasing network delay.Besides, when nodes identify malicious nodes during the verification in SAODV routing protocol, they won't inform other nodes in the network,allowing malicious nodes to move to other area and continue damaging network. To solve this problem, this thesis put forward cooperation mechanism among nodes: when nodes identify malicious nodes, they will send message invasion warning (IWAR) message to other nodes to isolate malicious nodes to network.In the end, simulation experiment is conducted on SAODV routing protocol and TCSAODV (Trust-based and Cooperation SAODV) routing protocol in NS2. Through the analysis of the simulation result, it's concluded that TCSAODV is more resource-and-time-saving than SAODV routing protocol.