Paper 2023/1876

Thwarting Last-Minute Voter Coercion

Rosario Giustolisi, IT University of Copenhagen
Maryam Sheikhi Garjan, IT University of Copenhagen
Carsten Schuermann, IT University of Copenhagen

Counter-strategies are key components of coercion-resistant voting schemes, allowing voters to submit votes that represent their own intentions in an environment controlled by a coercer. By deploying a counter-strategy a voter can prevent the coercer from learning if the voter followed the coercer’s instructions or not. Two effective counter-strategies have been proposed in the literature, one based on fake credentials and another on revoting. While fake-credential schemes assume that voters hide cryptographic keys away from the coercer, revoting schemes assume that voters can revote after being coerced. In this work, we present a new counter-strategy technique that enables flexible vote updating, that is, a revoting approach that provides protection against coercion even if the adversary is able to coerce a voter at the very last minute of the voting phase. We demonstrate that our technique is effective by implementing it in Loki, an Internet-based coercion-resistant voting scheme that allows revoting. We prove that Loki satisfies a game-based definition of coercion-resistance that accounts for flexible vote updating. To the best of our knowledge, we provide the first technique that enables deniable coercion- resistant voting and that can evade last-minute voter coercion.

Note: Appearing in the proceedings of the 45th IEEE Symposium on Security and Privacy S&P 2024

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Published elsewhere. IEEE Symposium on Security and Privacy (S&P 2024)
votingcoercion-resistancevote privacyverifiability
Contact author(s)
rosg @ itu dk
mashe @ itu dk
carsten @ itu dk
2023-12-06: approved
2023-12-06: received
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      author = {Rosario Giustolisi and Maryam Sheikhi Garjan and Carsten Schuermann},
      title = {Thwarting Last-Minute Voter Coercion},
      howpublished = {Cryptology ePrint Archive, Paper 2023/1876},
      year = {2023},
      note = {\url{}},
      url = {}
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