Paper 2019/017 Original: eprint.iacr.org/2019/017 ↗
CHURP: Dynamic-Committee Proactive Secret Sharing
Abstract
We introduce CHURP (CHUrn-Robust Proactive secret sharing). CHURP enables secure secret-sharing in dynamic settings, where the committee of nodes storing a secret changes over time. Designed for blockchains, CHURP has lower communication complexity than previous schemes: $O(n)$ on-chain and $O(n^2)$ off-chain in the optimistic case of no node failures. CHURP includes several technical innovations: An efficient new proactivization scheme of independent interest, a technique (using asymmetric bivariate polynomials) for efficiently changing secret-sharing thresholds, and a hedge against setup failures in an efficient polynomial commitment scheme. We also introduce a general new technique for inexpensive off-chain communication across the peer-to-peer networks of permissionless blockchains. We formally prove the security of CHURP, report on an implementation, and present performance measurements.
Metadata
- Available format(s)
PDF- Category
- Cryptographic protocols
- Publication info
- Preprint.
- History
- 2019-10-02: last updated
- 2019-01-09: published
- Short URL
- https://ia.cr/2019/017
- License
- https://creativecommons.org/licenses/by/4.0/
BibTeX
@misc{cryptoeprint:2019/017,
author = {Sai Krishna Deepak Maram and Fan Zhang and Lun Wang and Andrew Low and Yupeng Zhang and Ari Juels and Dawn Song},
title = {CHURP: Dynamic-Committee Proactive Secret Sharing},
howpublished = {Cryptology {ePrint} Archive, Paper 2019/017},
year = {2019},
url = {https://eprint.iacr.org/2019/017}
}