International Association for Cryptologic Research

International Association
for Cryptologic Research


Exploiting Intermediate Value Leakage in Dilithium: A Template-Based Approach

Alexandre Berzati , Thales DIS, Meudon, France
Andersson Calle Viera , Thales DIS, Meudon, France; Sorbonne Université, CNRS, Inria, LIP6, F-75005 Paris, France
Maya Chartouny , Thales DIS, Meudon, France; Université Paris-Saclay, UVSQ, CNRS, Laboratoire de mathématiques de Versailles, 78000, Versailles, France
Steven Madec , Thales DIS, Meudon, France
Damien Vergnaud , Sorbonne Université, CNRS, Inria, LIP6, F-75005 Paris, France
David Vigilant , Thales DIS, Meudon, France
DOI: 10.46586/tches.v2023.i4.188-210
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Abstract: This paper presents a new profiling side-channel attack on CRYSTALSDilithium, the new NIST primary standard for quantum-safe digital signatures. An open source implementation of CRYSTALS-Dilithium is already available, with constant-time property as a consideration for side-channel resilience. However, this implementation does not protect against attacks that exploit intermediate data leakage. We show how to exploit a new leakage on a vector generated during the signing process, for which the costly protection by masking is still a matter of debate. With a corpus of 700 000 messages, we design a template attack that enables us to efficiently predict whether a given coefficient in one coordinate of this vector is zero or not. By gathering signatures and being able to make the correct predictions for each index, and then using linear algebra methods, this paper demonstrates that one can recover part of the secret key that is sufficient to produce universal forgeries. While our paper deeply discusses the theoretical attack path, it also demonstrates the validity of the assumption regarding the required leakage model from practical experiments with the reference implementation on an ARM Cortex-M4. We need approximately a day to collect enough representatives and one more day to perform the traces acquisition on our target.
  title={Exploiting Intermediate Value Leakage in Dilithium: A Template-Based Approach},
  journal={IACR Transactions on Cryptographic Hardware and Embedded Systems},
  publisher={Ruhr-Universität Bochum},
  volume={2023, Issue 4},
  author={Alexandre Berzati and Andersson Calle Viera and Maya Chartouny and Steven Madec and Damien Vergnaud and David Vigilant},