A survey on optimistic fair exchange protocol and its variants

The notion of optimistic fair exchange (OFE) protocol was proposed by Asokan et al. in order to solve the problem of exchanging items or services in a fair manner between a signer and a verifier. There are various OFE protocols and variants in the literature, and they possess different security properties. In this paper, we provide an overview on the development of OFE protocol and its variants, namely, ambiguous OFE, perfect ambiguous OFE, privacy preserving OFE, accountable OFE, and group-oriented OFE. In precise, we investigate the security properties, evolutions and relationships among them. We also provide an evolution tree diagram to present their developments as well as three comparison analysis tables to compare and contrast their security properties.