Paper 2025/1669 Original: eprint.iacr.org/2025/1669 ↗

Experience from UNITA Elections: Reconciling Revote, E2E Verifiability and Low Coercion

Abstract

This paper presents an experience of designing, building and deploying an online voting system for the Student Assembly elections in the UNITA Alliance with the following requirements. First, the system should allow voters to vote as many times as they wish before the election’s closing time with only the last vote being counted (known as revote). Second, the system should allow end-to-end (E2E) verifiability. Third, the system should allow voters to cast votes under the minimum influence from external forces or coercion. Developing an online voting system to meet these requirements poses a unique challenge. In this pa- per, we present an online voting system for UNITA elections, based on a variant of the DRE-ip protocol to provide E2E verifiability with support for revote. The system adopts a two-server architecture and implements a separation of control between the two servers to protect the voter’s anonymity. The first UNITA elections were successfully concluded in March 2025, providing a case study for reconciling revote, E2E verifiability and low coercion in a real-world setting. The use of verifiable online voting to empower students from different European universities to elect the Student Assembly also serves as a model for more inclusive democratic governance of a university alliance.