  Online voting for independent elections is generally supported by trusted
election providers. Typically these providers do not offer any way in which a
voter can verify their vote, so the providers are trusted with ballot privacy
and ensuring correctness. Despite the desire to offer online voting for
political elections, this lack of transparency and verifiability is often seen
as a significant barrier to the large-scale adoption of online elections.
Adding verifiability to an online election increases transparency and
integrity, allowing voters to verify that their vote has been recorded
correctly and included in the tally. However, replacing existing online systems
with those that provide verifiable voting requires new algorithms and code to
be deployed, and this presents a significant business risk to commercial
election providers. In this paper we present the first step in an incremental
approach which minimises the business risk but demonstrates the advantages of
verifiability, by developing an implementation of key elements of a
Selene-based verifiability layer and adding it to an operational online voting
system. Selene is a verifiable voting protocol that uses trackers to enable
voters to confirm that their votes have been captured correctly while
protecting voter anonymity. This results in a system where even the election
authority running the system cannot change the result in an undetectable way,
and gives stronger guarantees on the integrity of the election than were
previously present. We explore the challenges presented by adding a
verifiability layer to an operational system. We describe the results of two
initial trials, which obtained that survey respondents found this form of
verifiability easy to use and that they broadly appreciated it. We conclude by
outlining the further steps in the road-map towards the deployment of a fully
trustworthy online voting system.
