P2P authenticity query and replica management algorithm based on trust

For the information sharing Peer-to-Peer (or P2P) systems, the document security is an important metric to evaluate the performance, so this paper concentrates on the optimization of document security in file sharing P2P system. For the highly autonomous P2P systems, because the document security in P2P systems mainly depends on two aspects: the security of the documents' carrier and the mechanisms related to the document, such as the replica management, the improvement of the document security can not depend on the improvement of the peers' security, but rely on the mechanisms related to the document. A query protocol sensitive to the document security is designed first in this paper. Based on this protocol, the mechanisms related to the document can be formally described as functions, and the improvement of the system document security can be transformed into the mathematical analyses on the function space. Derived from the results of mathematical analyses, a set of algorithms for replica managements are designed, aiming at improving the document security. In ideal situation, this set of algorithms can achieve the optimization for document security seen from the theoretical analyses, and in realistic systems, the algorithms can obtain good effects, approach to the optimal level. The algorithms are verified by lots of experimental results.