Research On Trust Model In P2P Based On Improved Chord Protocol

With the fast development of information technology, Peer-to-Peer network has become the focus in recent years. In the Peer-to-Peer system, the difference between the client and the server or the middle-layer disappears because that each node is seen as the same node which plays a role of client and server. Peer-to-Peer technology makes full use of users' resource on the edge of network to exchange and share useful information. In this way, more important information can be downloaded and uploaded more efficiently,a large amount of information can be stored. So Peer-to-Peer technology is widely applied in more practical cases such as coordinated computatuion, distributed storage.Peer-to-Peer technology brings us more chances,but it also brings us some chanllenge. Although Peer-to-Peer technology is anonymous, dynamic and exoteric, which enables it to offer more conveniece, it tends to be attacked. This case is resulted by the fact that in the early stage of designing Peer-to-Peer technology,factor of safety is not taken into account. Then how to design a better system in Peer-to-Peer to identify and defend,and in turn to restrict various attact is critical. Among so many ways, the way to award and compute each node's reputation has attracted more insterst because that this way is accords with social network.This article based on the improved Peer-to-Peer system model of Chord protocol to solve the problem of vicious beguiling behavior. This medel's basis is domain,in each domain all things are administrated by super nodes and between different domains information is changed with the main network through super nodes using Chord protocol.Thus influnce resulted by network's different structure become less,system's vibration because of some nodes' change are reduced and also various resource can be made full use of. Nodes in this kind of network using technology to share the different part of a file to download a file. when a node begins to download a file,this node informs his friend nodes(some other nodes in the same net),then these friend nodes according to their own resource and capability to download proper part of this file.Thus because of the cooperation between these nodes,working efficiency has been improved to a great extent.This article forwards maths model and concrete methods to estimate reputation of each nodes in distributed network in reference to social relation in practical life. This method does not compute reputation iteratively, but to compute it according to the theory of voting, thus the system can consume less resource. While during this process, factor of attenuation is considered, then each node is stimulated to offer better service. At last because that in this method computation of reputation take account into time and events, more harmful behaviors in this model are restrained toa great extent.