Paper 2023/1595
CDLS: Proving Knowledge of Committed Discrete Logarithms with Soundness
, Brave Software, University of AucklandAbstract
$\Sigma$-protocols, a class of interactive two-party protocols, which are used as a framework to instantiate many other authentication schemes, are automatically a proof of knowledge (PoK) given that they satisfy the "special-soundness" property. This fact provides a convenient method to compose $\Sigma$-protocols and PoKs for complex relations. However, composing in this manner can be error-prone. While they must satisfy special-soundness, this is unfortunately not the case for many recently proposed composed practical schemes. Here we explore two schemes: ZKAttest from Faz-Hernández et al. and the ones from Agrawal et al., and show that their $\Sigma$-protocol's suffer from several security misdesigns which invalidate their security proofs, and state a practical cheap attack on ZKAttest's implementation. By exploring and resolving their misdesigns, we propose CDLS, a sound and secure variant of their protocols.
Note: We resolve an error discovered in the reviews process with respect to the soundness of the proof of sum.
Metadata
- Available format(s)
-
PDF
- Category
- Attacks and cryptanalysis
- Publication info
- Preprint.
- Keywords
- Sigma-protocolsZero-KnowledgePoKElliptic-Curves
- Contact author(s)
-
cherenkov @ riseup net
shai levin @ auckland ac nz
Joe Rowell 2015 @ live rhul ac uk - History
- 2024-01-05: revised
- 2023-10-14: received
- See all versions
- Short URL
- https://ia.cr/2023/1595
- License
-
CC BY
BibTeX
@misc{cryptoeprint:2023/1595,
author = {Sofia Celi and Shai Levin and Joe Rowell},
title = {{CDLS}: Proving Knowledge of Committed Discrete Logarithms with Soundness},
howpublished = {Cryptology {ePrint} Archive, Paper 2023/1595},
year = {2023},
url = {https://eprint.iacr.org/2023/1595}
}
