The mechanism to control file-pollution based on hybrid trust-model in P2P network

File-pollution, which results in all kinds of malicious and unavailable files, such as Trojan, Sirius, into the network, is a common phenomenon. However, it decreases availability of files in network, threatens security of peers, badly hinders the development of P2P file-sharing network. Nowadays, research on file-pollution still focus on mathematical mode and observation of file-pollution on main popular P2P file-sharing network, and don't refer to effective anti-pollution mechanism. By considering impact of peers' behaviors to file-pollution, PFtrust mode was proposed. It not only restricts behavior of peers, but also identifies quality of contaminated files. Compared to other credit-based scheme, PFtrust performs much better in three aspects: convergence rate, speed to clean up contaminated file and speed to isolate malicious peer, which represents that it's an effective mechanism to control file-pollution.