The Research And Application Of Trust Management In Wireless Sensor Networks

Along with the rapid development of science and technology, the matureness of computing, wireless communication and micro-electronics technology have enabled the application fields of wireless sensor networks (WSNs) more and more widely. However, there exists many types of attacks threatening WSNs, such as malicious dropping packets attack, Sybil attack, Sinkhole attack and so on, which limit the development of WSNs. The security problems of WSNs have received the concern of more and more researches. How to safely communicate with each other is one of the key issues in WSNs. Encryption-based security mechanisms can resist external attacks, but they can't resolve internal attacks that caused by nodes been captured sometimes. Therfore, we need to establish an effective trust mechanism for distinguishing captured nodes timely. Encryption-based security solutions are not enough for WSNs when there are attacks from interior, which are caused by compromised nodes, selfish nodes or low competition nodes. Trust management which has strong research value can deal with these problems efficiently, and can enhance the security, reliability and impartiality of the system.By systematically analyzing existing trust models which are from domestic and foreign, and in view of the characteristics of WSNs, we present Effective and Energy savingβTrust Model which is applied to geographical and energy aware routing protocol in which the trust values of nodes are calculated for establishing trust routing. Trust routing protocol R-GEAR which is based on effective and energy savingβtrust model is built up and simulated in NS2.The main work of this thesis includes:(1) By systematically analyzing existing trust models which are from domestic and foreign, and in view of the characteristics of WSNs, we present Effective and Energy savingβTrust Model. Trust values of nodes are evaluated by collaboration of multiple nodes which monitor the evaluated nodes'behavior in packets forwarding to build trust relationship. And considering energy factor of sensor nodes in trust decision stage, choose the nodes whose energy are higer than the threshold as routing nodes, and this can keep load balancing. The trust model which adopts simple computing and avoid large communications is lightweight and adapts to energy limited WSNs.(2) According to the shortcomings of geographical and energy aware routing protocol (GEAR), a trust routing protocol R-GEAR is designed by introducing the effective and energy savingβtrust model into GEAR. Evaluate trust values of nodes with the trust model to establish trust routing with nodes which are highly trusted. Then considering energy factor of sensor nodes, use data fusion to reduce the packets which needed to be forwarded, by which greatly reduces the consumption of sensor nodes'energy and extends the use time of the node in WSNs. The trust routing protocol can extend the survival time of WSNs and enhance its security.(3) Trust routing protocol R-GEAR and energy aware routing protocol GEAR are simulated in NS2. We test the reliability and energy consumption of the algorithm with such aspects: packets delivery ratio, packets drop ratio, and the number of packets which need to be transmitted in WSNs. And then compare the performance of R-GEAR with that of GEAR. The simulation result shows that the performance of R-GEAR is better than that of GEAR. The simulation result validates the ability of effective and energy savingβtrust model that it can judge the trustworthiness of a node more accurately, keep minimum resource utilization and enhance the security of the network.