An Efficient Rational Secret Sharing Protocol Resisting against Malicious Adversaries over Synchronous Channels

Abstract

Current works solve the problem of rational secret sharing from one or some, but not all, of the following aspects: achieving a more appealing equilibrium concept, avoiding strong communication models and resisting against adversaries. To address one issue above, they need to lower the satisfaction in other issues. In this paper we construct a t-out-of-n rational secret sharing protocol, which achieves an enhanced notion of computational strict Nash equilibrium with respect to adversary structure $\mathcal{A}$, runs over synchronous (non-simultaneous) broadcast channels and tolerates a malicious adversary who controls a minority of players. To the best of our knowledge, compared with current works tolerating adversaries, we are the first to yield positive results in all the three research aspects above. The feasibility of our protocol is based on the use of publicly verifiable secret sharing. Under the assumptions related to discrete logarithm and ElGamal cryptosystem, computational bounded players have an incentive not to deviate no matter how adversaries behave.