Cross and clean: Amortized garbled circuits with constant overhead

Abstract

Garbled circuits (GC) are one of the main tools for secure two-party computation. One of the most promising techniques for efficiently achieving active-security in the context of GCs is the so called cut-and-choose approach, and the main measure of efficiency in cut-andchoose based protocols is the number of garbled circuits which need to be constructed, exchanged and evaluated. In this paper we investigate the following, natural question: how many garbled circuits are needed to achieve active security? and we show that in the amortized setting (for large enough circuits and number of executions), it is possible to achieve active security while using only a constant number of garbled circuits.