Optimally-Fair Exchange of Secrets via Delay Encryption and Commutative Blinding
Ivo Maffei, Andrew William Roscoe · Lecture notes in computer science · 2023
Abstract We propose a new fair exchange protocol that takes advantage of delay encryption and commutative encryption to achieve optimal partial fairness among all protocols involving one-way messages. Our protocol consists of 3 setup messages and $$2N+1$$ 2 N + 1 exchange messages and it is fair against covert adversaries with probability $$1- \frac{1}{2N}$$ 1 - 1 2 N . We prove that this is optimal up to shortening the setup phase which is notably more efficient than existing protocols.