Trade-offs between reliability and overheads in peer-to-peer reputation tracking

The success of incentive techniques to motivate freeriders to contribute resources in file-sharing Gnutella-like peer-to-peer networks depends on the availability of peer behavior tracking in terms of resource consumption and contribution. Though many reputation systems have been proposed toward the goal of behavior tracking, the overheads incurred in such tracking have received little attention. Consideration of overheads is an important factor in judging the merits of a practical reputation tracking scheme in order to maintain the scalability of the underlying peer-to-peer network. This paper proposes two methods of reputation tracking: strong and weak reputations. These methods differ in the trade-offs between reliability of reputation tracking and the overheads incurred. We formally specify and verify strong reputations and note that while the scheme yields highly reliable reputation tracking, the reliability and overhead trade-offs in weak reputations present a more viable alternative for large peer-to-peer networks.