Paper 2024/031

Feldman's Verifiable Secret Sharing for a Dishonest Majority

Yi-Hsiu Chen, Coinbase
Yehuda Lindell, Coinbase
Abstract

Verifiable secret sharing (VSS) protocols enable parties to share secrets while guaranteeing security (in particular, that all parties hold valid and consistent shares) even if the dealer or some of the participants are malicious. Most work on VSS focuses on the honest majority case, primarily since it enables one to guarantee output delivery (e.g., a corrupted recipient cannot prevent an honest dealer from sharing their value). Feldman's VSS is a well known and popular protocol for this task and relies on the discrete log hardness assumption. In this paper, we present a variant of Feldman's VSS for the dishonest majority setting and formally prove its security. Beyond the basic VSS protocol, we present a publicly-verifiable version, as well as show how to securely add participants to the sharing and how to refresh an existing sharing (all secure in the presence of a dishonest majority). We prove that our protocols are UC secure, for appropriately defined ideal functionalities.

Metadata
Available format(s)
PDF
Category
Cryptographic protocols
Publication info
Preprint.
Keywords
Verifiable secret sharing (VSS)
Contact author(s)
yihsiuc @ pm me
yehuda lindell @ gmail com
History
2024-03-21: last of 2 revisions
2024-01-08: received
See all versions
Short URL
https://ia.cr/2024/031
License
Creative Commons Attribution
CC BY

BibTeX

@misc{cryptoeprint:2024/031,
      author = {Yi-Hsiu Chen and Yehuda Lindell},
      title = {Feldman's Verifiable Secret Sharing for a Dishonest Majority},
      howpublished = {Cryptology {ePrint} Archive, Paper 2024/031},
      year = {2024},
      url = {https://eprint.iacr.org/2024/031}
}
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