  Voting protocols seek to provide integrity and vote privacy in elections. To
achieve integrity, procedures have been proposed allowing voters to verify
their vote - however this impacts both the user experience and privacy.
Especially, vote verification can lead to vote-buying or coercion, if an
attacker can obtain documentation, i.e. a receipt, of the cast vote. Thus, some
voting protocols go further and provide mechanisms to prevent such receipts. To
be effective, this so-called receipt-freeness depends on voters being able to
understand and use these mechanisms. In this paper, we present a study with 300
participants which aims to evaluate the voters' experience of the
receipt-freeness procedures in the e-voting protocol Selene in the context of
vote-buying. This actually constitutes the first user study dealing with
vote-buying in e-voting. While the usability and trust factors were rated low
in the experiments, we found a positive correlation between trust and
understanding.
