An optimistic fair exchange protocol for P2P e-procurement

This paper presents an optimistic fair exchange protocol based on public verifiable secret sharing for e-procurement applications in Peer-2-Peer networks. According to the decentralized feature of such a network, a distributed third party is designed to guarantee the fairness of exchange. Comparing to traditional trusted third party, this distributed third party is not fixed but dynamically selected by the players of exchange. This scheme can effectively remove the risk of single point of failure and defend Distributed Denial of Service. The concrete protocol is elaborated in this paper. The protocol analysis shows that the protocol guarantees strong fairness with up to one-half malicious peers in distributed third party.