The Research On Trust Model In P2P Environments

Nowadays Peer-to-Peer(P2P) computing has become a hot research issue. The goal of P2P computing is to pool end-systems in Internet-scale as more as possible to construct large-scale cooperating and resource-sharing environments.Because the following problem directly decide the usability and practicability of P2P system, it has been in dire need of a solution. In decentralized P2P environments, due to the anonymous and autonomous nature of peers, they have to manage the risk involved with the interaction without prior experience and knowledge about each other's reputation. Trust models can be used to quantify and to evaluate the trustworthiness of peers so as to reduce the risk.The dissertation focuses on this problem, and makes these contributions:1. A comprehensive survey of trust models in P2P environments is made. The newly-proposed models are analyzed, classified and compared.2. Distance-weighted Trust Model (DTM), a global trust model, is presented, which includes a mathematical description and a distributed implementation. Trust models in P2P environments have two main challenges: various malicious behavior of peers such as providing fake or misleading recommendation about other peers; decentralized and secure trust data management. Previous global trust models are based on the assumption that the peers with high trust value will give the honest recommendation. But this assumption may not hold in all cases. In DTM, each peer is assigned a unique global trust value, computed by aggregating distant-weighted recommendations of the peers who have interacted with it. Theoretical analyses and experiments show that the scheme is still robust under more general conditions where malicious peers cooperate in an attempt to deliberately subvert the system, converges more quickly and decreases the numbers of inauthentic files downloaded more effectively than previous schemes. Furthermore, a decentralized trust data management scheme is given and the anonymity requirements of peers for securing trust data are also considered.