Secure Multiparty Computation vs. Fair Exchange - Bridging the Gap

In this paper, we propose a comparison of two seemingly similar problems, i.e., secure multiparty computation and fair exchange. However, if these two problems appear to bear a lot in common, they come from fields that differ greatly in the way the problems are described and approached, i.e., the fields of modern cryptography and distributed systems respectively. In that regard, straightforward comparison of the various results and solutions can be hazardous. Our first contribution is to propose a common specification framework. We then propose to reduce the gap between the two problems by translating them into the new specification framework. This first step allows us to shed light on the differences regarding the generality of these problems, which then leads us to specify a new problem, named the fair multiparty computation. This third problem helps understanding the relations between secure multiparty computation and fair exchange, by bridging the gap between them. We then propose a solution to the newly introduced problem of fair multiparty computation. Finally, we conclude with a discussion of the differences found in the literature regarding various results and approaches.