Cryptology ePrint Archive: Report 2011/310

Universally Composable Synchronous Computation

Jonathan Katz and Ueli Maurer and Bjoern Tackmann and Vassilis Zikas

Abstract: In synchronous networks, protocols can achieve security guarantees that are not possible in an asynchronous world: i.e., they can simultaneously achieve input completeness (all honest parties’ inputs are included in the computation) and guaranteed termination (honest parties do not “hang” indefinitely). In practice truly syn- chronous networks rarely exist, but synchrony can be emulated if channels have (known) latency and parties have loosely synchronized clocks.

The framework of universal composability (UC) is inherently asynchronous, but several approaches for adding synchrony to the framework have been proposed. However, we show that the existing proposals do not provide the expected guarantees. Given this, we propose a “clean slate” approach to defining synchrony in the UC framework by introducing functionalities exactly meant to model, respectively, bounded-delay networks and loosely synchronized clocks. We show that the expected guarantees of synchronous computation can be realized given these functionalities, and that previous models can all be expressed within our new framework.

Category / Keywords: cryptographic protocols /

Original Publication (with minor differences): IACR-TCC-2013

Date: received 10 Jun 2011, last revised 26 Oct 2013

Contact author: vzikas at cs ucla edu

Available format(s): PDF | BibTeX Citation

Version: 20131026:194047 (All versions of this report)

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