Research On P2P Network Security Model Based On L-Fuzzy Set And Its Application

The issues of P2P trust is mainly sdudied in the dissertation. Fristly, on the basis of L-fuzzy set and fuzzy inference theory, a fuzzy inferrence model with three I fuzzy reasoning algorithm is put forward, and a comprehensive evaluation and fuzzy reasoning program is given. Secondly, based on this trust model, a secure P2P access control mechanism with fuzzy multi-level security policy is made. Thirdly, studied the issues in P2P content distribution system, a key link generation algorithm and content distribution mechanism based on fuzzy trust are put forward.Finally, The main topics of this dissertation are listed as follows:(1) On the basis of analysis of existing P2P network trust model, L-fuzzy set and fuzzy inference theory, a fuzzy inferrence model with three I fuzzy reasoning algorithm is put forward. In the model, using linguistic variable to describe the relationship of trust between entities, fuzzy variables to characterize the meaning of trust, and fuzzy logic to describe the recommendation relationship between trust among entities. Finally, trust in a multiple recommended rule is fuzzy reasoned. The simulation results show that the model can improve the success rate of transactions largely, can make a better trust relationship with nodes, and has better ability of anti-malicious nodes.(2) A secure P2P access control mechanism with fuzzy multi-level security policy is made based on this trust model with analysis of the P2P network access control problem. With the global trust as secret level of a node, in rule of the least privilege to subject, it can securely access to shared resources in P2P network. The simulation results show that the mechanism can improve success access rate for resource largely, and can effectively identify the malicious nodes.(3) A key link generation algorithm and content distribution mechanism based on fuzzy trust are put forward with analysis the additional overhead issues of P2P content distribution system based on network coding. In this mechanism,fuzzy trust as the primary constraint to labeling algorithm, then network coding is made on the key node,which can solve the problem of encoding failure. The simulation results show that netwoke encoding on the key nodes on key link in P2P content distribution system can further reduce the encoding overhead and system failure rate.(4) With this trust model, a fuzzy task scheduling algorithm is given for the task scheduling issues in P2P computing environment. In which,fuzzy trust as a primary constraint, based on Min-min, Max-min and Sufferage heuristic task scheduling algorithm, construct a new scheduling algorithm. The simulation results show that the scheduling algorithm can further reduce the makespan and the average execution time of a task.