Peer-to-Peer (P2P) systems are distributed self-organized systems without a controlling entity where peers need to make trust decisions regarding who they will transact with. P2P reputation systems exploit past transactional information to provide members of P2P networks with measures which will help them make such trust decisions. However, these systems are vulnerable themselves to various types of attacks which can distort their functionality and credibility. A number of defense mechanisms have been proposed to counteract specific attacks, but research lacks an exploration of how these mechanisms can be used together so as to provide the highest degree of credibility. In this paper, after presenting the basic attacks and defense mechanisms concerning P2P reputation systems, we analyze the tradeoffs between different credibility enhancing mechanisms and ways to achieve the right balances. Our aim is to help reputation systems designers to incorporate in their systems the right mechanisms or the right combinations of mechanisms against the threats of the specific reputation systems.
['Eleni Koutrouli', 'Aphrodite Tsalgatidou']
P2P Reputation Systems Credibility Analysis: Tradeoffs and Design Decisions