Paper 2026/188
A Visit to KAZ Attack: Finding a Minor Flaw and a Simplified Lattice Construction
Abstract
Inspired by a recent paper from Shanghai Jiao Tong University and China Telecom Quantum Information Technology Group [1]—which demonstrated a full break of the KAZ algorithm family submitted to Malaysia’s MySEAL 2.0 standardization—we focus specifically on its signature component. Within the same core theoretical framework, we have observed a subtle inaccuracy in the formula given in the original work. While this does not prevent the final private-key recovery via lattice reduction, it leads to incorrect derivation of the intermediate sensitive signature data e₁ and e₂. Building on this observation, we propose a refined lattice construction that successfully reproduces the original attack while eliminating the need for an additional step: computing the greatest common divisor (GCD) between the signature component S₂ and the modulus ϕ(N). This new construction is equally capable of recovering the private key using two signatures.
Metadata
- Available format(s)
-
PDF
- Category
- Attacks and cryptanalysis
- Publication info
- Preprint.
- Keywords
- KAZPQCLattice reduction
- Contact author(s)
-
yongbohu @ spric org cn
chenzhang @ spric org cn
gmzhou @ spric org cn - History
- 2026-02-06: approved
- 2026-02-05: received
- See all versions
- Short URL
- https://ia.cr/2026/188
- License
-
CC BY
BibTeX
@misc{cryptoeprint:2026/188,
author = {Yongbo Hu and Chen Zhang and Guomiao Zhou},
title = {A Visit to {KAZ} Attack: Finding a Minor Flaw and a Simplified Lattice Construction},
howpublished = {Cryptology {ePrint} Archive, Paper 2026/188},
year = {2026},
url = {https://eprint.iacr.org/2026/188}
}
