An Efficient Open Vote Network for Multiple Candidates

In 2010, Hao et al. proposed an efficient decentralized voting protocol known as Open Vote Network (OV-Net), which does not require a trusted third party to count the votes or a private channel to protect ballot secrecy. In the last decade, various studies have been conducted to solve some limitations of the OV-Net, such as fairness and robustness. However, an unresolved problem exists in the OV-Net (and its variants), which is its limited scalability for multiple candidates. The computational cost for tallying, which increases exponentially with the number of candidates, causes the scalability problem. Therefore, in this study, we solve this problem by proposing a variant of the OV-Net for multiple candidates and showing that the computational cost of tallying increases linearly with the number of candidates. Regarding security, we prove that our variant satisfies the ballot secrecy and dispute-freeness in formal security models, based on the decision Diffie-Hellman assumption and non-interactive zero-knowledge properties, respectively. Moreover, regarding the efficiency, we compare the performance of the traditional and proposed OV-Net from the theoretical standpoint and present experimental results to show that the proposed OV-Net variant is considerably more efficient than the traditional OV-Net as the numbers of voters and candidates increase.