A new efficient optimistic fair exchange protocol without random oracles

A traceable optimistic fair exchange protocol in the standard model

An Optimistic Fair Exchange (OFE) protocol is a good way for two parties to exchange their digital items in a fair way such that at the end of the protocol execution, both of them receive their items or none of them receive anything. In an OFE protocol there is a semi-trusted third party, named arbitrator, which involves in the protocol if it is necessary. But there is a security problem when a...

The Construction of Ambiguous Optimistic Fair Exchange from Designated Confirmer Signature without Random Oracles

Ambiguous Optimistic Fair Exchange (AOFE), introduced by Huang et al. in ASIACRYPT 2008, is an extension of OFE that enhances the fairness of the two communicating parties in the exchange of signatures. The first scheme was proven secure without random oracles while its partial signature contains dozens of group elements. Recently, interactive AOFE was introduced and the construction is more pr...

Efficient Optimistic Fair Exchange Secure in the Multi-user Setting and Chosen-Key Model without Random Oracles

Optimistic fair exchange is a kind of protocols to solve the problem of fair exchange between two parties. Almost all the previous work on this topic are provably secure only in the random oracle model. In PKC 2007, Dodis et al. considered optimistic fair exchange in a multiuser setting, and showed that the security of an optimistic fair exchange in a single-user setting may no longer be secure...

A Diffie-Hellman Key Exchange Protocol Without Random Oracles

Optimistic Fair Exchange Protocol for E-Commerce

For e-commerce payments, fair exchange is one of the essential problems. The optimistic fair exchange protocol allows two parties to efficiently exchange items so that either each party gets the other’s item or neither does. We propose a new optimistic fair exchange protocol that is efficient and applicable to any digital signature scheme such as RSA or DSA. In our protocol, we introduce pre-si...