Paper 2022/1653

Reversing, Breaking, and Fixing the French Legislative Election E-Voting Protocol

Alexandre Debant, Université de Lorraine, CNRS, Inria, LORIA, F-54000 Nancy, France
Lucca Hirschi, Université de Lorraine, CNRS, Inria, LORIA, F-54000 Nancy, France
Abstract

We conduct a security analysis of the e-voting protocol used for the largest political election using e-voting in the world, the 2022 French legislative election for the citizens overseas. Due to a lack of system and threat model specifications, we built and contributed such specifications by studying the French legal framework and by reverse-engineering the code base accessible to the voters. Our analysis reveals that this protocol is affected by two design-level and implementation-level vulnerabilities. We show how those allow a standard voting server attacker and even more so a channel attacker to defeat the election integrity and ballot privacy due to 6 attack variants. We propose and discuss 5 fixes to prevent those attacks. Our specifications, the attacks, and the fixes were acknowledged by the relevant stakeholders during our responsible disclosure. Our attacks are in the process of being prevented with our fixes for future elections. Beyond this specific protocol, we draw general conclusions and lessons from this instructive experience where an e-voting protocol meets the real-world constraints of a large-scale and political election.

Metadata
Available format(s)
PDF
Category
Attacks and cryptanalysis
Publication info
Preprint.
Keywords
e-voting security protocols software analysis security and privacy
Contact author(s)
alexandre debant @ inria fr
lucca hirschi @ inria fr
History
2022-11-28: revised
2022-11-28: received
See all versions
Short URL
https://ia.cr/2022/1653
License
Creative Commons Attribution-NonCommercial
CC BY-NC

BibTeX

@misc{cryptoeprint:2022/1653,
      author = {Alexandre Debant and Lucca Hirschi},
      title = {Reversing, Breaking, and Fixing the French Legislative Election E-Voting Protocol},
      howpublished = {Cryptology ePrint Archive, Paper 2022/1653},
      year = {2022},
      note = {\url{https://eprint.iacr.org/2022/1653}},
      url = {https://eprint.iacr.org/2022/1653}
}
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