Cryptanalysis of an Efficient Signature Based on Isotropic Quadratic Forms

Henry Bambury; Phong Q. Nguyen

Paper 2025/133

Cryptanalysis of an Efficient Signature Based on Isotropic Quadratic Forms

Henry Bambury, DIENS, Ecole normale supérieure, PSL University, CNRS, Inria, Paris, France, DGA, Paris, France

Phong Q. Nguyen, DIENS, Ecole normale supérieure, PSL University, CNRS, Inria, Paris, France

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: Published elsewhere. Minor revision. PQCrypto 2025
Keywords: Cryptanalysis Digital Signatures Lattices Multivariate Cryptography Quadratic Forms
Contact author(s): henry bambury @ m4x org
phong nguyen @ inria fr
History: 2025-01-28: approved; 2025-01-28: received; See all versions
Short URL: https://ia.cr/2025/133
License: CC BY

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}
}