Paper 2025/1482

Complex Elections via Threshold (Fully) Homomorphic Encryption

Georgio Nicolas, KU Leuven

Nigel P. Smart, Zama, KU Leuven

Abstract

We discuss how Fully Homomorphic Encryption (FHE), and in particular the TFHE scheme, can be used to define an e-voting scheme for the Alternative Vote (AV) election system. This system has a more complex tallying phase than traditional First-Past-The-Post (FPTP) election variants. Previous work on e-voting schemes that used homomorphic encryption has focused on FPTP systems only, and utilized mainly linearly homomorphic encryption. We show, by using FHE, that more complex electoral systems such as AV can also be supported by homomorphic encryption. We show security of our protocol by considering it as a simple MPC functionality, and we also show practicality by presenting some experimental runtimes using the tfhe-rs library.

Note: Improvements in implementation explanation and runtime

@misc{cryptoeprint:2025/1482,
      author = {Charlotte Bonte and Georgio Nicolas and Nigel P. Smart},
      title = {Complex Elections via Threshold (Fully) Homomorphic Encryption},
      howpublished = {Cryptology {ePrint} Archive, Paper 2025/1482},
      year = {2025},
      url = {https://eprint.iacr.org/2025/1482}
}