An optimistic fair exchange protocol with active intermediaries

The study of business transactions is a topic of interest in the field of electronic commerce. Fair Exchange protocols deal with the problem of how the different parties involved in a transaction can exchange their parts securely, i.e., with assurance that the other parties will carry on with the transaction. Fair Exchange is a field of research that has been extensively studied, but we have found that previous proposals have failed to address one problem that concerns electronic commerce, i.e., transactions with active intermediaries. Previous Fair Exchange protocols deal with scenarios where only 2 parties are involved or scenarios where N known parties have to reach a common agreement, omitting scenarios where active intermediaries are involved. In this paper, we present an Optimistic Fair Exchange protocol for transactions with active intermediaries, which, to the best of our knowledge, is the first of its kind.