Trust Models And Incentive Mechanisms For P2P Networks

Peer-to-Peer(P2P) has become the overwhelming technology for the internet as its benefits over traditional client-server approaches to cooperative working, data sharing and large scale parallel computing. The basic assumption of P2P networks is that peers are willing to share resoures with others. However, the realitiy is that the private provision of public goods causes free-riding and the tragedy of the commons in P2P networks. In fact, the rational users of P2P networks are self-interest and self-determination. The object of them is to maximize the personal utility without considering the whole network productivity. In addition, there still exist a large amount of P2P services with unreliable qualities and malicious actions. Therefore, to improve the performance of P2P networks, the peers' voluntary operations must be taken into account as well as the incentive mechanism which incent peers cooperate and consume resources rationally. This dissertation studies the problems of unrealiable services and uncooperation in P2P networks, and results in the following achievements:(1) A Reciprocal Capacity based Adaptive Topology Protocol (RC-ATP) for P2P networks is proposed in this thesis. It is based on the rational belief that a peer is only willing to maintain connections with those which will benefit it in future. Reciprocal capacity is defined based on peers' capacity of providing services and of recommending service providers. As a result, reciprocal peers connect each other adequately. In addition, a response selction mechanism is proposed to reduce the probability of trying to download files from malicious peers. Therefore, the resulting topologies are more efficient and resilient than Adaptive Peer-to-Peer Topologies (APT). Furthermore, RC-ATP has the intrinsic incentive to active peers as they are more advantaged and important in the network than free-riders and malicious peers. Although the overhead of the topology adaptation is a bit higher, RC-ATP works more efficiently with less cost compared with the Adaptive Peer-to-Peer Topologies Protocol (APTP).(2) A group based reputation system GroupRep for P2P networks is proposed. In...