Keeping Peers Honest In EigenTrust

A fundamental consideration in designing successful trust scores in a peer-to-peer system is the self-interest of individual peers. We propose a strategyproof partition mechanism that provides incentives for peers to share files, is non-manipulable by selfish interests, and approximates trust scores based on EigenTrust[5]. The basic idea behind the partition mechanism is that the peers are partitioned into peer groups and incentives are structured so that a peer only downloads from peers in one particular peer group. When peers are myopic, we show that the total error in the trust values decreases exponentially with the number of peer groups, but when peers plan for the future, the total error decreases linearly with the number of peer groups. There is a direct tradeoff here between approximating EigenTrust well and keeping the trust values we are approximating useful.