Research And Design On Trust Model Of P2P Network

P2P applications are developing at a tremendous pace, thus security risks are introduced.There are lots of deceptions and unreliable services in the network. The traditional centralized trust management does not adapt to the P2P network. Current trust model could not promise the convergence of iteration for trust computation, and takes no consideration for security problems, such as disguise and slandering. This thesis presents a domain and recommendation based multi-granularity trust model, called DRM model.In DRM model, trust is composed of local trust and global trust, which are given different weights to show how much the users rely on the direct experience and the global opinion. Local trust is obtained according to the trade history between the local node and the objective node; global trust is gained by the recommendations and the global trusts of nodes which have businesses with the objective node before. Mathematic analyses prove that the proposed model is complete on iteration for computing peer trust.The P2P network is divided into several domains so that the storage and computation costs of the global trust is reduced. The distributed hash table mechanism is used to lay the global trusts, and a distributed protocol is designed to compute them. The complexity of the protocol is in constant level, which is much more extensible then current models. Public key system, data redundancy and some parameters are introduced to resist evil behaviors, such as false service, disguise, slandering, boasting, alteration,etc.. Therefore the network is more robust in dealing with security problems.Current model is ambiguous in the expression of trust. Multi-granularity trust expresses the ability and interest of nodes in every specific field, thus users can make their decisions more clearly.The simulations show that, compared to the current trust model, the DRM model is more robust in resisting evil behaviors and could calculate trust in specific field more exactly. Therefore the quality of service in P2P network is highly improved.