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Finding a polytope: A practical fault attack against Dilithium

Authors:
Paco Azevedo Oliveira , Laboratoire de Mathématiques de Versailles
Andersson Calle Viera , Sorbonne Université, LIP6
Benoît Cogliati , Thales DIS
Louis Goubin , Laboratoire de Mathématiques de Versailles
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Conference: PKC 2025
Abstract: In Dilithium, the rejection sampling step is crucial for the proof of security and correctness of the scheme. However, to our knowledge, there is no attack in the literature that takes advantage of an attacker knowing rejected signatures. The aim of this paper is to create a practical black-box attack against Dilithium with a weakened rejection sampling. We succeed in showing that an adversary with enough rejected signatures can recover Dilithium's secret key in less than half an hour on a desktop computer. There is one possible application for this result: by physically preventing one of the rejection sampling tests from happening, we obtain two fault attacks against Dilithium.
BibTeX
@inproceedings{pkc-2025-35163,
  title={Finding a polytope: A practical fault attack against Dilithium},
  publisher={Springer-Verlag},
  author={Paco Azevedo Oliveira and Andersson Calle Viera and Benoît Cogliati and Louis Goubin},
  year=2025
}