On black-box complexity of universally composable security in the CRS model

Abstract

In this work, we study the intrinsic complexity of blackbox Universally Composable (UC) secure computation based on general assumptions. We present a thorough study in various corruption modelings while focusing on achieving security in the common reference string (CRS) model. Our results involve the following: – Static UC Secure Computation. Designing the first static UC secure oblivious transfer protocol based on public-key encryption and stand-alone semi-honest oblivious transfer. As a corollary we obtain the first black-box constructions of UC secure computation assuming only two-round semi-honest oblivious transfer. – One-sided UC Secure Computation. Designing adaptive UC secure two-party computation with single corruptions assuming public-key encryption with oblivious ciphertext generation. – Adaptive UC Secure Computation. Designing adaptively secure UC commitment scheme assuming only public-key encryption with oblivious ciphertext generation. As a corollary we obtain the first black-box constructions of adaptive UC secure computation assuming only (trapdoor) simulatable public-key encryption (as well as a variety of concrete assumptions). We remark that such a result was not known even under non-black-box constructions.