From Error to Error: Why Voters Could not Cast a Ballot and Verify Their Vote With Helios, Prêt à Voter, and Scantegrity II

The aim of this paper is to identify user errors, and the related potential design deficiencies, that contributed to participants failing to vote cast and vote verify across three end-to-end voting systems: Helios, Prêt à Voter, and Scantegrity II. To understand why voters could not cast a vote 42% of the time and verify that their ballots were cast and counted with the tested e2e systems 53% of the time, we reviewed data collected during a system usability study. An analysis of the findings revealed subjects were most often not able to vote with Helios because they did not log in after encrypting their ballot but before casting it. For both Prêt à Voter and Scantegrity II, failing to vote was most frequently attributed to not scanning the completed ballot. Across all three systems, the most common reason participants did not verify their vote was due to not casting a ballot in the first place. While there were numerous usability failures identified in the study, these errors can likely be designed out of the systems. This formative information can be used to avoid making the same types of mistakes in the next generation of voting systems—ultimately resulting in more usable e2e methods.