Rational Secure Two-party Computation in Social Cloud

Abstract

Rational parties in secure two-party computation (STPC) are willing to maximize their utilities. However, they have no incentives to cooperate in STPC under correctness and exclusivity assumptions since cooperation will bring them inferior utilities. Consequently, both parties will not participate in STPC. Therefore, new methods must be introduced to make parties cooperate such that they can complete this computation task. In this paper, we redefine utility considering the notion of reputation derived from social cloud to promote cooperation. In social cloud, parties form their reputation when they interact with others. Parties will get a higher utility if they have a higher cooperative reputation. Therefore they have incentives to cooperate. The computation of reputation is completed in the social cloud, which reduce the computation work for parties. Furthermore, we prove that given proper parameters in rational STPC, it is possible to construct an efficient computation protocol, where only one exchanging round in the second stage of the hybrid protocol.