A Secure Verifiable Ranked Choice Online Voting System Based on Homomorphic Encryption

Advanced security methods are necessary to introduce effective online voting in the whole world. Elections conducted on paper consume a lot of resources and contribute to the destruction of forests, which leads to climate deterioration. Recent online voting experiences in countries, such as the United States, India, and Brazil, demonstrated that further research is needed to improve security guarantees for future elections, to ensure the confidentiality of votes and enable the verification of their integrity and validity. In this paper, we propose a ranked choice online voting system, which addresses these challenges. It eliminates all hardwired restrictions on the possible assignments of points to different candidates according to the voters' personal preferences. In order to protect the confidentiality of the votes, each cast ballot is encrypted using the exponential ElGamal cryptosystem before submission. Furthermore, during voting the system ensures that proofs are generated and stored for each element in the cast ballot. These proofs can then be used to verify the correctness and the eligibility of each ballot before counting without decrypting and accessing the content of the ballot. This validates the votes in the counting process and at the same time maintains confidentiality. The security and performance analyses included in this paper demonstrate that our method has achieved significant improvements in comparison with the previous systems. The outcomes of our experiments also show that our proposed protocols are feasible for practical implementations.