Round-efficient black-box construction of composable multi-party computation

Abstract

We present a round-efficient black-box construction of a general MPC protocol that satisfies composability in the plain model. The security of our protocol is proven in angel-based UC framework under the minimal assumption of the existence of semi-honest oblivious transfer protocols. When the round complexity of the underlying oblivious transfer protocol is rOT(n), the round complexity of our protocol is max(Õ(log2n), O(r OT(n))). Since constant-round semi-honest oblivious transfer protocols can be constructed under standard assumptions (such as the existence of enhanced trapdoor permutations), our result gives Õ(log 2n)-round protocol under these assumptions. Previously, only an O(max(nε, rOT (n)))-round protocol was shown, where ε > 0 is an arbitrary constant. We obtain our MPC protocol by constructing a Õ(log2n)-round CCA-secure commitment scheme in a black-box way under the assumption of the existence of one-way functions. © 2014 International Association for Cryptologic Research.