More efficient match-making and satisfiability. The five card trick

Abstract

A two-party cryptographic protocol for evaluating any binary gate is presented. It is more efficient than previous two-party computations, and can even perform single-party (i.e. satisfiability) proofs more efficiendy than known techniques. As in all earlier multiparty computations and satisfiability protocols, commitments are a fundamental building block. Each party in our approach encodes a single input bit as 2 bit commitments. These are then combined to form 5 bit commitments, which are permuted, and can then be opened to reveal the output of the gate.