Abstract
This paper presents an efficiency study of fair exchange protocols for Multi-Party Contract Signing (MPCS) from their architecture point of view, an approach that has not been previously explored. A set of common topologies is presented and defined: ring, star sequential and mesh. Some common terms and notions, such as round and message, are defined according to the topology where they are applied. The suitability of such common terms to measure the efficiency of the protocols is discussed. Finally, we present the design of optimal asynchronous optimistic MPCS protocols for different topologies and evaluate them under the unified definition/criterion of the efficiency parameters. These results are important to support secure and efficient online business which is part of our efforts for building secure and smart cyber society.