[Paper Review] An Incoercible E-Voting Scheme Based on Revised Simplified Verifiable Re-encryption Mix-nets

Shinsuke Tamura, Hazim Anas Haddad+2 more|arXiv (Cornell University)|Dec 17, 2015

Internet Traffic Analysis and Secure E-voting15 references3 citations

TL;DR

This paper proposes an incoercible e-voting scheme based on a revised simplified verifiable re-encryption mix-net (SVRM), enabling strong privacy, end-to-end verifiability, fairness, and robustness. By integrating erasable-state voting booths, the scheme prevents coercers from determining voters' choices even under coercion, except when voters are forced to abstain, while ensuring correct tabulation without recounts despite illegitimate vote handling.

ABSTRACT

Simplified verifiable re-encryption mix-net (SVRM) is revised and a scheme for e-voting systems is developed based on it. The developed scheme enables e-voting systems to satisfy all essential requirements of elections. Namely, they satisfy requirements about privacy, verifiability, fairness and robustness. It also successfully protects voters from coercers except cases where the coercers force voters to abstain from elections. In detail, voters can conceal correspondences between them and their votes, anyone can verify the accuracy of election results, and interim election results are concealed from any entity. About incoercibility, provided that erasable-state voting booths which disable voters to memorize complete information exchanged between them and election authorities for constructing votes are available, coercer C cannot know candidates that voters coerced by C had chosen even if the candidates are unique to the voters. In addition, elections can be completed without reelections even when votes were handled illegitimately.

Motivation & Objective

• To address the lack of incoercibility in existing e-voting systems, where coercers may extract vote information through vote-buying or coercion.
• To enhance privacy and verifiability in electronic voting by refining the simplified verifiable re-encryption mix-net (SVRM) construction.
• To ensure that even under coercion, coercers cannot determine which candidate a voter selected, except in cases of forced abstention.
• To maintain system robustness by allowing elections to complete correctly even if votes are handled illegitimately.
• To provide a practical, efficient, and secure e-voting framework that satisfies all core election requirements.

Proposed method

• The authors revise the original simplified verifiable re-encryption mix-net (SVRM) to improve security and efficiency in e-voting applications.
• The scheme employs verifiable re-encryption to shuffle and re-encrypt votes, ensuring that vote content remains hidden during tabulation.
• It introduces erasable-state voting booths that prevent voters from memorizing or recording complete communication transcripts with election authorities.
• The system enables public verification of vote integrity and correct tallying by any third party using cryptographic proofs.
• The mix-net structure ensures that no single authority can link votes to voters, preserving privacy and fairness.
• The protocol supports robustness by allowing election completion without recounts even if some votes are processed incorrectly.

Experimental results

Research questions

• RQ1 Can a verifiable re-encryption mix-net be revised to support incoercibility in e-voting systems?
• RQ2 How can erasable-state voting booths be effectively integrated to prevent coercion attacks?
• RQ3 To what extent does the revised SVRM scheme preserve privacy and verifiability under adversarial conditions?
• RQ4 Can the system ensure correct tabulation without requiring recounts, even when votes are handled illegitimately?
• RQ5 Does the scheme maintain fairness and robustness while preventing coercers from learning voters' choices?

Key findings

• The proposed scheme successfully achieves incoercibility under the assumption that erasable-state voting booths are available, preventing coercers from learning voters' choices except in cases of forced abstention.
• The system ensures end-to-end verifiability, allowing anyone to cryptographically verify the correctness of the final election result.
• Vote privacy is preserved because no entity, including election authorities, can link votes to voters due to the mix-net's shuffling and re-encryption mechanism.
• Interim results are concealed from all entities, including election officials and voters, ensuring secrecy during tabulation.
• The system remains robust and completes elections correctly even if some votes are handled illegitimately, eliminating the need for recounts.
• The revised SVRM construction reduces complexity while maintaining strong security guarantees, making it suitable for practical deployment.