Trust Model In P2p-based Distributed Environment

The application of the P2P develops vigorously, while some hidden problems which exist in the P2P technology can not be covered up,the biggest hidden problem is the security issue that lies in mutual-trust between nodes. Because the P2P system is a high degree of openness and freedom, any node can be unimpeded as the same role of the peer in the system. The difference between the nodes is great, this difference is reflected not only in the objective capacity of the node, but also reflected in the subjective desires of nodes. The content of this paper is the P2P Trust Model, the model's main purpose is to study how to regulate the different will of the node, how to restrict excessive freedom and arbitrariness. P2P mode and the traditional C/S mode is very different, making centralism trust mechanism for building trust model on P2P environment is no reference, we must re-build the P2P Trust Model in the distributed environment.The most of the existing P2P trust models have a complex structure, and they are too hard to implement to the project, as well as they consume of the system too much. This paper presents a new trust model, the model has a simple and pertinence calculate arithmetic of the reputation, the model topology structure is optimized; the model has small price, easy maintenance and high reliability. The basic idea of the trust model is: on the design algorithm of the reputation, we aimed at the various problems of the existing P2P systems, extracted various factors reasonably, classed accurately, and made the algorithm of the reputation authentic and intuitionistic; on the design of the reputation, we proposed the concept of the resources reputation and the node reputation, the former examine the authenticity of resources and the other check the credibility of the node; on the topology structure of the model, based on the degree of the node, we choose some nodes as CenterNode, and then by the CenterNode designated domain, then by the CenterNode and the leaf node formed the two-tier management topology structure; on the process of the establishment of trust relations, the model judge the node reputation firstly, and then judged resources reputation, in this way it ensure the reliability of the trust relationship. The results of the model simulation show that, based on the domain topology structure has obvious advantages in the inquire time and consume information. The trust model based on such structure can be able to isolate malicious node effectively, so can ensure higher quality of service. This model has important application value for establishing a steady and reliable circumstance of the P2P.