International Association for Cryptologic Research

International Association
for Cryptologic Research


Environmentally Friendly Composable Multi-Party Computation in the Plain Model from Standard (Timed) Assumptions

Brandon Broadnax
Jeremias Mechler
Jörn Müller-Quade
DOI: 10.1007/978-3-030-90459-3_25
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Abstract: Starting with the work of Rivest et al. in 1996, timed assumptions have found many applications in cryptography, building e.g. the foundation of the blockchain technology. They also have been used in the context of classical MPC, e.g. to enable fairness. We follow this line of research to obtain composable general MPC in the plain model. This approach comes with a major advantage regarding environmental friendliness, a property coined by Canetti et al. (FOCS 2013). Informally, this means that our constructions do not “hurt” game-based security properties of protocols that hold against polynomial-time adversaries when executed alone. As an additional property, our constructions can be plugged into any UC-secure protocol without loss of security. Towards proving the security of our constructions, we introduce a variant of the UC security notion that captures timed cryptographic assumptions. Combining standard timed commitment schemes and standard polynomial-time hardness assumptions, we construct a composable commitment scheme in the plain model. As this construction is constant-round and black-box, we obtain the first fully environmentally friendly composable constant-round black-box general MPC protocol in the plain model from standard (timed) assumptions.
Video from TCC 2021
  title={Environmentally Friendly Composable Multi-Party Computation in the Plain Model from Standard (Timed) Assumptions},
  booktitle={Theory of Cryptography;19th International Conference},
  author={Brandon Broadnax and Jeremias Mechler and Jörn Müller-Quade},