Comparative Usability Evaluation of Cast-as-Intended Verification Approaches in Internet Voting

Abstract

Internet Voting promises benefits like the support for voters from abroad and an overall improved accessibility. But it is accompanied by security risks like the manipulation of votes by malware. Enabling the voters to verify that their voting device casts their intended votes is a possible solution to address such a manipulation - the so-called cast-as-intended verifiability. Several different approaches for providing cast-as-intended verifiability have been proposed or put into practice. Each approach makes various assumptions about the voters' capabilities that are required in order to provide cast-as-intended verifiability. In this paper we investigate these assumptions of four chosen cast-as-intended approaches and report the impact if those are violated. Our findings indicate that the assumptions of cast-as-intended approaches (e.g. voters being capable of comparing long strings) have an impact on the security the Internet Voting systems. We discuss this impact and provide recommendations how to address the identified assumptions and give important directions in future research on usable and verifiable Internet Voting systems.