关键词: 可信, 可信评估, 可信评估模型, 半环, Ad-Hoc网络

Abstract: The notion of trust，in the realm of network security，will for our purposes correspond to a set of relations among entities that participate in a protocol.These relations are based on the evidence generated by the previous interactions of entities within a protocol.To enhance security in Ad-Hoc networks，it is important to evaluate the trustworthiness of other nodes without centralized authorities.In this work，authors focus on the evaluation of trust evidence in Ad Hoc networks.First，the authors introduce the metrics of the trust，the evaluation process is modeled as a path problem on a directed graph，where nodes represent entities，and edges represent trust relations.Using the theory of semirings，a trust evaluation model based on semiring（TD-SEMIRING） is developed，then two nodes can establish an indirect trust relation without previous direct interaction and introduce the application of this model in route election.At last，the feasibility of this model is analyzed.

Key words: trust, trust evaluation, trust model, semiring, Ad-Hoc networks