Paper 2025/379 Original: eprint.iacr.org/2025/379 ↗
A Complete Security Proof of SQIsign
Abstract
SQIsign is the leading digital signature from isogenies. Despite the many improvements that have appeared in the literature, all its recents variants lack a complete security proof. In this work, we provide the first full security proof of SQIsign, as submitted to the second round of NIST's on-ramp track for digital signatures. To do so, we introduce a new framework, which we call Fiat-Shamir with hints, that captures all those protocols where the simulator needs additional information to simulate a transcript. Using this framework, we show that SQIsign is EUF-CMA secure in the ROM, assuming the hardness of the One Endomorphism problem with hints, or the hardness of the Full Endomorphism Ring problem with hints together with a hint indistinguishability assumption; all assumptions, unlike previous ones in the literature, are non-interactive. Along the way, we prove several intermediate results that may be of independent interest.
Metadata
- Available format(s)
PDF- Category
- Public-key cryptography
- Publication info
- Preprint.
- History
- 2025-08-01: last updated
- 2025-02-27: published
- Short URL
- https://ia.cr/2025/379
- License
- https://creativecommons.org/licenses/by/4.0/
BibTeX
@misc{cryptoeprint:2025/379,
author = {Marius A. Aardal and Andrea Basso and Luca De Feo and Sikhar Patranabis and Benjamin Wesolowski},
title = {A Complete Security Proof of SQIsign},
howpublished = {Cryptology {ePrint} Archive, Paper 2025/379},
year = {2025},
url = {https://eprint.iacr.org/2025/379}
}