Communications in Cryptology IACR CiC

Feldman's Verifiable Secret Sharing for a Dishonest Majority

Authors

Yi-Hsiu Chen, Yehuda Lindell
Yi-Hsiu Chen ORCID
Coinbase, USA
yihsiuc at pm dot me
Yehuda Lindell ORCID
Coinbase, USA
yehuda dot lindell at gmail dot com

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.

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DOI: https://doi.org/10.62056/ak2isgvtw
History
Submitted: 2024-01-08
Accepted: 2024-03-05
Published: 2024-04-09
How to cite

Yi-Hsiu Chen and Yehuda Lindell, "Feldman's Verifiable Secret Sharing for a Dishonest Majority," IACR Communications in Cryptology, vol. 1, no. 1, Apr 09, 2024, doi: 10.62056/ak2isgvtw.

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