Paper 2011/310

Universally Composable Synchronous Computation

Jonathan Katz, Ueli Maurer, Bjoern Tackmann, and Vassilis Zikas


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.

Available format(s)
Cryptographic protocols
Publication info
A minor revision of an IACR publication in TCC 2013
Contact author(s)
vzikas @ cs ucla edu
2013-10-26: revised
2011-06-13: received
See all versions
Short URL
Creative Commons Attribution


      author = {Jonathan Katz and Ueli Maurer and Bjoern Tackmann and Vassilis Zikas},
      title = {Universally Composable Synchronous Computation},
      howpublished = {Cryptology ePrint Archive, Paper 2011/310},
      year = {2011},
      note = {\url{}},
      url = {}
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