Efficient distributed reputation scheme for peer-to-peer systems

Reputation systems for Peer-to-Peer (P2P) networks are relatively new. Most of the existing systems are centrally controlled hence raising scalability issues and single points of failure. In this paper we present a completely decentralized reputation scheme for P2P networks. The system is based on a certificate, RCert, which is a document that resides on a participating P2P node, which consists of information ratings collected from previous transactions with other peers. Central to the scheme is the concept of Public Key Infrastructure (PKI), upon on which much of the mechanism is based. In order to facilitate updates of RCert certificates, we present two protocols, RCertP and RCertPX. RCertP does not prevent the node from using older copies of RCert. An extended version, RCertPX, solves this problem by keeping track of the latest timestamp.