Paper 2019/017
CHURP: Dynamic-Committee Proactive Secret Sharing
Sai Krishna Deepak Maram and Fan Zhang and Lun Wang and Andrew Low and Yupeng Zhang and Ari Juels and Dawn Song
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.
Note: Minor error fix.
Metadata
- Available format(s)
- Category
- Cryptographic protocols
- Publication info
- Preprint. MINOR revision.
- Keywords
- secret sharingthreshold cryptographyblockchains
- Contact author(s)
- sm2686 @ cornell edu
- History
- 2019-10-02: last of 5 revisions
- 2019-01-09: received
- See all versions
- Short URL
- https://ia.cr/2019/017
- License
-
CC BY