Paper 2025/628 Original: eprint.iacr.org/2025/628 ↗
Improving the Masked Division for the FALCON Signature
Abstract
FALCON is a post-quantum signature selected by the National Institute of Standards and Technology (NIST). Although its side-channel resilience has been studied and a masking countermeasure proposed, the division is a major performance bottleneck. This work proposes a different approach to the masked FALCON division. We use the Newton-Raphson method and a convergent sequence to approximate this operation. The first term of the sequence is evaluated using pre-calculated second-order minimax polynomials. As a consequence, computing the inverse only requires 5 masked additions and 8 masked multiplications, compared to the roughly 55 masked additions required by the previous state-of-the-art. Formal security proofs using the MIMO-SNI criteria are also provided.
Metadata
- Available format(s)
PDF- Category
- Implementation
- Publication info
- Preprint.
- History
- 2026-07-16: last updated
- 2025-04-07: published
- Short URL
- https://ia.cr/2025/628
- License
- https://creativecommons.org/licenses/by/4.0/
BibTeX
@misc{cryptoeprint:2025/628,
author = {Pierre-Augustin Berthet and Cédric Tavernier and Justine Paillet and Yousuf Alsalami and Majid Khonji and Chan Yeun and Hani Saleh and Muna A. Alshehhi and Ahmed S. Al Ali},
title = {Improving the Masked Division for the FALCON Signature},
howpublished = {Cryptology {ePrint} Archive, Paper 2025/628},
year = {2025},
url = {https://eprint.iacr.org/2025/628}
}