Addition of ElGamal plaintexts

Abstract

We introduce an efficient method for performing computation on encrypted data, allowing addition of ElGamal encrypted plaintexts. We demonstrate a solution that is robust and leaks no information to a minority of colluding cheaters. Our focus is on a three-player solution, but we also consider generalization to a larger number of players. The amount of work is exponential in the number of players, but reasonable for small sets.