Research On Anti-Pollution Strategy In Peer-to-Peer Sharing System

Peer-to-Peer (P2P) file-sharing system is becoming more and more popular in the Internet, showing its unique charm. However, its openness, autonomy and anonymity have brought a lot of security problems, such as file pollution problem in P2P file-sharing system. File pollution is a phenomenon that attacker release files which have been changed intentionally in the system, or publish files which have the same name with others but their content is empty or contains malicious code. If there are a lot of pollution files in the system, it will not only damage the security and mutually beneficial sharing environment of resource and increase a lot of unnecessary communication overhead, but also make the spread of viruses, worms and other malicious programs convenient. It will cause a serious damage to the file sharing system and may lead users to abandon the system eventually by affecting the experience of users.In this paper, the concept of field theory was introduced first. Based on the in-depth study in the phenomenon of file pollution in the sharing system, the idea of field theory was introduced, based on the management of pollution degree, a pollution field is constructed, which is composed by a number of pollution slicks. Measuring the pollution level of the peers by pollution degree, which was managed by the neighbor peers.An anti-pollution strategy is proposed based on the field theory in this paper. In the process of querying message, when a query message enters the pollution field, it will generate a repulsion to the message, at the same time, the message will generate a forward momentum to the pollution field for entering it to find more hit results of the file. With the interaction between the message and pollution field, our strategy could control the behavior of pollution peers effectively by determining whether the message could enter the pollution field. According to the phenomenon that pollution peers more likely to choose the popular file as a carrier, popularity factor is introduced in the anti-pollution strategy as the basis for classification punishment to pollution peers. In order to reduce the spread of pollution file effectively. We make the peers who have higher pollution degree can only get files have lower popularity. Moreover, we also maintain a blacklist of polluting file in the local of peer based on the pollution degree of file, to achieve the purpose of curbing the spread of pollution files in a maximum extent in the process of response message.