CCS'19

CHURP: Dynamic-Committee Proactive Secret Sharing

SKD Maram*, F. Zhang*, L. Wang, A. Low, Y. Zhang, A. Juels, and D. Song

*indicates equal contribution

ACM CCS 2019
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TL;DR by AI

CHURP enables proactive secret sharing for dynamic committees in blockchains with low communication complexity.

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.
Highlights
Publicity
  • Invited talk at ACM CCS'19, London, UK.
  • Invited talk at IC3 Bootcamp, Ithaca, NY.

Cite this paper

BibLaTeX
@inproceedings{DBLP:conf/ccs/MaramZWLZJS19,
  author       = {Sai Krishna Deepak Maram and
                  Fan Zhang and
                  Lun Wang and
                  Andrew Low and
                  Yupeng Zhang and
                  Ari Juels and
                  Dawn Song},
  editor       = {Lorenzo Cavallaro and
                  Johannes Kinder and
                  XiaoFeng Wang and
                  Jonathan Katz},
  title        = {{CHURP:} Dynamic-Committee Proactive Secret Sharing},
  booktitle    = {Proceedings of the 2019 {ACM} {SIGSAC} Conference on Computer and
                  Communications Security, {CCS} 2019, London, UK, November 11-15, 2019},
  pages        = {2369--2386},
  publisher    = {{ACM}},
  year         = {2019},
  url          = {https://doi.org/10.1145/3319535.3363203},
  doi          = {10.1145/3319535.3363203}
}