We design and analyze a simple optimistic fair non-repudiation protocol. Our protocol is considerably simpler and more efficient than current proposals, due mainly to the avoidance of using session labels. We model-check both safety and liveness properties. We verify the safety properties using a standard intruder, and the liveness properties using an intruder that respects the resilient communication channels assumption. Finally, to provide further confidence in the protocol we expose several vulnerabilities on weaker versions of our protocol.
J. G. Cederquist, Ricardo Corin, Muhammad Torabi D