(2026-06) Actively Secure MPC with O(-C-) Computation and Communication via CRT
2026-06-17
Secure multiparty computation (MPC) allows parties to compute a function of their private inputs, so that nothing beyond the output of the function is revealed. In the sub-optimal honest majority setting in which the number of corrupted parties , the works of Goyal et al. (CRYPTO'21 and CRYPTO'22), achieved communication even against active adversaries, but with computation, where is the arithmetic circuit computed by the MPC. Recent work by Garg et al. (CRYPTO'24) showed that both communication and computation can be achieved in this regime, however, only against passive adversaries. In this work, we achieve the best-of-both-worlds by obtaining MPC with communication and computation against active corruption of parties. To do this, we introduce novel techniques for actively-secure MPC constructed from Chinese Remainder Theorem based secret sharing.