Cryptanalysis of an Efficient Signature Based on Isotropic Quadratic Forms

Henry Bambury; Phong Q. Nguyen

Paper 2025/133 Original: eprint.iacr.org/2025/133 ↗

Cryptanalysis of an Efficient Signature Based on Isotropic Quadratic Forms

Henry Bambury

Phong Q. Nguyen

Abstract

We present a key-recovery attack on DEFI, an efficient signature scheme proposed recently by Feussner and Semaev, and based on isotropic quadratic forms, borrowing from both multivariate and lattice cryptography. Our lattice-based attack is partially heuristic, but works on all proposed parameters: experimentally, it recovers the secret key in a few minutes, using less than ten (message,signature) pairs.

Metadata

Available format(s): PDF
Category: Attacks and cryptanalysis
Publication info: Preprint.
History: 2025-01-28: last updated; 2025-01-28: published
Short URL: https://ia.cr/2025/133
License: https://creativecommons.org/licenses/by/4.0/

BibTeX

@misc{cryptoeprint:2025/133,
      author = {Henry Bambury and Phong Q. Nguyen},
      title = {Cryptanalysis of an Efficient Signature Based on Isotropic Quadratic Forms},
      howpublished = {Cryptology {ePrint} Archive, Paper 2025/133},
      year = {2025},
      url = {https://eprint.iacr.org/2025/133}
}