Verifiable Mix-Nets and Distributed Decryption for Voting from Lattice-Based Assumptions

Diego F. Aranha, Kristian Gjøsteen, Carsten Baum, Tjerand Silde

Research output: Chapter in Book/Report/Conference proceedingConference contributionpeer-review

2 Scopus citations

Abstract

Cryptographic voting protocols have recently seen much interest from practitioners due to their (planned) use in countries such as Estonia, Switzerland, France, and Australia. Practical protocols usually rely on tested designs such as the mixing-and-decryption paradigm. There, multiple servers verifiably shuffle encrypted ballots, which are then decrypted in a distributed manner. While several efficient protocols implementing this paradigm exist from discrete log-type assumptions, the situation is less clear for post-quantum alternatives such as lattices. This is because the design ideas of the discrete log-based voting protocols do not carry over easily to the lattice setting, due to specific problems such as noise growth and approximate relations. This work proposes a new verifiable secret shuffle for BGV ciphertexts and a compatible verifiable distributed decryption protocol. The shuffle is based on an extension of a shuffle of commitments to known values which is combined with an amortized proof of correct re-randomization. The verifiable distributed decryption protocol uses noise drowning, proving the correctness of decryption steps in zero-knowledge. Both primitives are then used to instantiate the mixing-and-decryption electronic voting paradigm from lattice-based assumptions. We give concrete parameters for our system, estimate the size of each component and provide implementations of all important sub-protocols. Our experiments show that the shuffle and decryption protocol is suitable for use in real-world e-voting schemes.

Original languageEnglish
Title of host publicationCCS 2023 - Proceedings of the 2023 ACM SIGSAC Conference on Computer and Communications Security
PublisherAssociation for Computing Machinery, Inc
Pages1467-1481
Number of pages15
ISBN (Electronic)9798400700507
DOIs
StatePublished - 15 Nov 2023
Externally publishedYes
Event30th ACM SIGSAC Conference on Computer and Communications Security, CCS 2023 - Copenhagen, Denmark
Duration: 26 Nov 202330 Nov 2023

Publication series

NameCCS 2023 - Proceedings of the 2023 ACM SIGSAC Conference on Computer and Communications Security

Conference

Conference30th ACM SIGSAC Conference on Computer and Communications Security, CCS 2023
Country/TerritoryDenmark
CityCopenhagen
Period26/11/2330/11/23

Bibliographical note

Publisher Copyright:
© 2023 Copyright held by the owner/author(s).

Keywords

  • Electronic Voting
  • Implementation
  • Lattice-Based Cryptography

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