Preserving privacy of feedback providers in decentralized reputation systems

Reputation systems make the users of a distributed application accountable for their behavior. The reputation of a user is computed as an aggregate of the feedback provided by other users in the system. Truthful feedback is clearly a prerequisite for computing a reputation score that accurately represents the behavior of a user. However, it has been observed that users often hesitate in providing truthful feedback, mainly due to the fear of retaliation. We present a decentralized privacy preserving reputation protocol that enables users to provide feedback in a private and thus uninhibited manner. The protocol has linear message complexity, which is an improvement over comparable decentralized reputation protocols. Moreover, the protocol allows users to quantify and maximize the probability that their privacy will be preserved.