Mobile Ad Hoc Networks Under The Trust Model And Its Application

Due to its improvised nature, an ad hoc network holds the promise of the future with its appealing capability to establish networks at anytime, anywhere. However, its main features known as self-organizing and highly dynamic also lead to many security vulnerabilities. Traditional solutions can not deal with intelligent attacks that seem more covert and stochastic. Besides, they fail to solve the problem of collaboration under trust for distributed applications. As an alternative, trust model that simulates real-life human interactions can impose a good restriction on nodes'concucts in networks by the use of a reputation mechanism. It can implement security strategies from a higher layer and thus serves as an efficient way to secure ad hoc networks. Under such background, our thesis does some innovative research on trust model and its application.First, fundamental issues related to the modeling and evaluation of a trust model are discussed, which leads to a theoretic framework of trust in ad hoc networks.Second, a novel trust model termed as the dynamic subjective trust model based on inference with uncertainty is proposed. It uses an evidence-based inteference system to achieve intelligence in human thinking. Concepts such as time utility and similarity utility are introduced to incorporate attributes of trust such as dynamics, subjectivity and uncertainty into the model. Besides, a novel decision algorithm based on evaluation of gains and risks is presented. Furthermore, some practical techniques are developed to implement the model, which is followed its functional diagram and working flow chart.Third, a trust-based routing algorithm is proposed as a concrete application of our trust model in ad hoc networks. It uses trust as the binding force to restrict nodes'packet forwarding behaviours. It endeavors to encourage social collaborations and at the same time to isolate malicious nodes so that the overall routing performance can be enhanced. Besides, some security specifications are added to protect the routing algorithm itself.Finally, we analyze the features and performance of our proposed trust model both theoretically and experimentally.