Comparing “Challenge-Based” and “Code-Based” Internet Voting Verification Implementations

Abstract

Internet-enabled voting introduces an element of invisibility and unfamiliarity into the voting process, which makes it very different from traditional voting. Voters might be concerned about their vote being recorded correctly and included in the final tally. To mitigate mistrust, many Internet-enabled voting systems build verifiability into their systems. This allows voters to verify that their votes have been cast as intended, stored as cast and tallied as stored at the conclusion of the voting period. Verification implementations have not been universally successful, mostly due to voter difficulties using them. Here, we evaluate two cast as intended verification approaches in a lab study: (1) "Challenge-Based" and (2) "Code-Based". We assessed cast-as-intended vote verification efficacy, and identified usability issues related to verifying and/or vote casting. We also explored acceptance issues post-verification, to see whether our participants were willing to engage with Internet voting in a real election. Our study revealed the superiority of the code-based approach, in terms of ability to verify effectively. In terms of real-life Internet voting acceptance, convenience encourages acceptance, while security concerns and complexity might lead to rejection.

Towards Improving the Efficacy of Code-Based Verification in Internet Voting

“…Some users were unable to detect the manipulation to the verification code in the original system. This observation is different from the results of the study in [15], where all the participants were able to detect the manipulation using a code-based verification similar to the Swiss system. One possible explanation might be that the participants in the previous study were explicitly instructed to verify their vote, whereas in our study the focus was on casting a vote.…”

“…Although both the original and improved systems received high SUS scores, the complexity of the procedure and the codes was an issue, again confirming the findings from [15]. Voters might well be willing to accept complex systems if they are told that the complexity is necessary for security (see [16]).…”

“…In the attacks simulated in the study, no such code was sent, but only 6 of 30 participants detected this. Similar to [15], the voting interface was unaffected by the manipulations. No specific evaluation has been carried out to detect whether voters detect user interface manipulations while verifying their cast votes.…”

“…Some studies evaluated the effectiveness of code-based verification by deliberately introducing manipulations during the process. Kulyk et al [15] evaluated the effectiveness of a code-based approach and manipulated the verification code, replacing it with an incorrect code. While all participants detected the manipulation, the removal of the verification code was not tested.…”

Æternum: A Decentralized Voting System with Unconditional Privacy

“…Hence, IV can only be provided if we assume a trusted platform on the voter's side, but this is impractical. A more practical solution that gives some relief to the problem is to have the voter Challenge-or-Cast the ballot with a second independent device [34]. Also note that the querying of the DPBB for a specific ballot should only happen over a non-anonymous channel (same as casting the ballot).…”