Implementing and Evaluating the Usability of Reliable Voter Complaints in E2E Verifiable Remote Electronic Voting

End-to-end (E2E) verifiable remote electronic voting is often discussed as an alternative to postal voting for voters living abroad. Such systems require voters to verify that their vote is recorded as intended and to complain if this is not the case. The challenge with voters living abroad is to provide them with a usable, reliable online channel to file their complaints. The contributions of our paper are: (1) Proposal of such a reliable mechanism for a well-established voting scheme including the adoption of voting material to support it. (2) Evaluation of the proposal’s effect on the usability (i.e. effectiveness, efficiency, and satisfaction of the voting process) and the manipulation detection rate on the voting scheme. (3) Evaluation of the effectiveness of the complaint filing mechanism. The study comprised two phases in which 150 participants cast their votes over the internet after receiving the voting material by postal mail. The first phase focused on the usability and the second one (being deceptive) simulated a manipulation, examining the manipulation detection rate and the effectiveness of the complaint filing mechanism. Our results show a significant improvement in efficiency, without any negative impact on other usability dimensions or participants’ ability to detect manipulations. Among those who detected the manipulation in the second phase, 73% used the complaint filing mechanism correctly, while the rest would have filed a complaint to the attacker who had manipulated their vote in the first place. We conclude that the proposed reliable complaint channel can and should be integrated into E2E verifiable remote voting systems and outline ways to help more voters use it effectively.