In P2P networks, there are no incentives to cooperate. There is
neither a reward for cooperation nor a punishment for
non-cooperation. A distributed reputation system could solve
this problem, by giving means of managing trust towards other
entities and discovering vicious entities. The existing
distributed reputation systems are based on plausibility
considerations and, thus, have several limitations. Therefore,
in this report, we aim at overcoming these limitations by
proposing the Buddy System as a distributed reputation system
that is based on social structure.
For this purpose, we discuss the design space of social
structures and choose an appropriate social structure for the
We consider implementation issues for its social structure by
taking into account the volatility of the P2P network.
Finally, we show by the means of simulation that the Buddy
System significantly improves the effectiveness and efficiency
of conventional distributed reputation systems. More
specifically, the Buddy System is more effective in the
detection of vicious entities and does not introduce any
additional communication overhead.