Individual Verifiability with Return Codes: Manipulation Detection Efficacy

Abstract. Researchers advocate for end-to-end verifiable voting
schemes to maximise election integrity. At E-Vote-ID 2021, Kulyk et al.
proposed to extend the verifiable scheme used in Switzerland (called original scheme) by voting codes to improve it with respect to vote secrecy.
While the authors evaluated the general usability of their proposal, they
did not evaluate its efficacy with respect to manipulation detection by
voters. To close this gap, we conducted a corresponding user study. Furthermore, we study the effect of a video intervention (describing the vote
casting process including individual verifiabilty steps) on the manipulation detection rate. We found that 65% of those receiving the video
detected the manipulation and informed the support. If we only consider
those who stated they (partially) watched the video the rate is 75%. The
detection rate for those not having provided the video is 63%. While
these rates are significantly higher than the 10% detection rate reported
in related work for the original system, we discuss how to further increase
the detection rate