Many of today’s e-voting systems in controlled environments produce physical evidence of the vote cast in the form of paper receipts for the voters (often referred to as VVPAT). Voters can verify their vote on the receipt and then deposit the receipt in a ballot box. By manually re-counting the receipts, the results presented by the voting system can be independently verified. The results of an entire election can be verified by a well-designed manual recount of receipts from a random sample of polling stations.
E-voting systems in uncontrolled environments commonly do not produce physical evidence as these could be used for vote-selling. Additionally, as the voter would keep the receipt, a manual recount is not possible, which renders such receipts useless. However, some Internet voting systems utilize a return code system that allows voters to verify that their vote was received unaltered by the counting server.
If e-voting systems provide no physical evidence of the votes cast, direct verification of results is not possible.2 The results produced by such a system can only be indirectly verified. Indirect verification relies exclusively on a strict certification process against agreed standards in combination with tight security measures that prevent any violation of the voting system’s integrity. In these circumstances it can be difficult to communicate the reliability and trustworthiness of the e-voting system in a transparent way to a critical or non-expert audience. This might become an insurmountable challenge in a context where the EMB does not enjoy the full trust of the electoral stakeholders.
Adding a paper trail makes e-voting systems more complex and expensive. Bearing in mind the fact that many voters do not check their receipts, as well as possible mistakes in the manual recount and the need to resolve discrepancies between the electronic count and the paper count, paper trails are not a perfect solution for guaranteeing accurate and transparent elections. Still, if implemented in conjunction with proper audit procedures and mandatory random sample recounts, they become an important tool that makes it easier to build stakeholders’ trust. Paper trails allow the verification of electronic election results and make it possible to identify any faults or manipulation in an observable and easily understandable process. The lack of a paper trail is often one of the first issues raised by opponents of electronic voting.