Improving cooperation in peer-to-peer systems using social networks

Rational and selfish nodes in P2P systems usually lack effective incentives to cooperate, contributing to the increase of free-riders, and degrading the system performance. Various attacks such as whitewashing, collusion, and software cracking pose great challenges on distributed reputation management. To tackle these problems, we propose to build a social network on P2P system, and use the strength of social connections to facilitate transactions in P2P system. The´ small world´ character of social networks makes it feasible for nodes to locate resources and conduct transactions while maintain limited local memory history. Such distributed memory combined by relationship between peers constructs a powerful reputation management network, which could have better performance than shared history system and is more robust under various attacks. Our simulation and analysis show that the social network model can greatly incent cooperation in P2P networks and enormously reduce the memory cost.