Paper 2010/229

Concurrent composition in the bounded quantum storage model

Dominique Unruh

Abstract

We define the BQS-UC model, a variant of the UC model, that deals with protocols in the bounded quantum storage model. We present a statistically secure commitment protocol in the BQS-UC model that composes concurrently with other protocols and an (a-priori) polynomially-bounded number of instances of itself. Our protocol has an efficient simulator which is important if one wishes to compose our protocol with protocols that are only computationally secure. Combining our result with prior results, we get a statistically BQS-UC secure protocol for general two-party computation without the need for any setup assumption. The round complexity of that protocol is linear in the circuit depth.

Note: - Earlier version mistakenly claimed a *constant-round* two-party computation protocol. - Various smaller changes