An efficient protocol for fair secure two-party computation

the 1980s, Yao presented a very efficient constant-round secure two-party computation protocol withstanding semi-honest adversaries, which is based on so-called garbled circuits. Later, several protocols based on garbled circuits covering malicious adversaries have been proposed. Only a few papers, however, discuss the fundamental property of fairness for two-party computation. So far the protocol by Pinkas (Eurocrypt 2003) is the only one which deals with fairness for Yao’s garbled circuit approach. In this paper, we improve upon Pinkas’ protocol by presenting a more efficient variant, which includes several modifications including one that fixes a subtle security problem with the computation of the so-called majority circuit. We prove the security of our protocol according to the real/ideal simulation paradigm, as Lindell and Pinkas recently did for the malicious case (Eurocrypt 2007)