Paper 2016/093 Original: eprint.iacr.org/2016/093 ↗
Valiant's Universal Circuit is Practical
Abstract
Universal circuits (UCs) can be programmed to evaluate any circuit of a given size $k$. They provide elegant solutions in various application scenarios, e.g. for private function evaluation (PFE) and for improving the flexibility of attribute-based encryption (ABE) schemes. The optimal size of a universal circuit is proven to be $\Omega(k\log k)$. Valiant (STOC'76) proposed a size-optimized UC construction, which has not been put in practice ever since. The only implementation of universal circuits was provided by Kolesnikov and Schneider (FC'08), with size $\mathcal{O}(k\log^2 k)$. In this paper, we refine the size of Valiant's UC and further improve the construction by (at least) $2k$. We show that due to recent optimizations and our improvements, it is the best solution to apply in the case for circuits with a constant number of inputs and outputs. When the number of inputs or outputs is linear in the number of gates, we propose a more efficient hybrid solution based on the two existing constructions. We validate the practicality of Valiant's UC, by giving an example implementation for PFE using these size-optimized UCs.
Metadata
- Available format(s)
PDF- Category
- Cryptographic protocols
- Publication info
- Preprint.
- History
- 2016-02-19: last updated
- 2016-02-02: published
- Short URL
- https://ia.cr/2016/093
- License
- https://creativecommons.org/licenses/by/4.0/
BibTeX
@misc{cryptoeprint:2016/093,
author = {Ágnes Kiss and Thomas Schneider},
title = {Valiant's Universal Circuit is Practical},
howpublished = {Cryptology {ePrint} Archive, Paper 2016/093},
year = {2016},
url = {https://eprint.iacr.org/2016/093}
}