Voting systems aim to provide trustworthiness in elections; however, they have
always been a target of malicious behaviours due to difficulties in designing such
complex systems and the enormous value of controlling the election results, causing
unfair election outcome, loss of personal privacy and trust in democracy. This
thesis aims to shed light on how voting systems, in particular, paper-based ones
can be evaluated so as to provide a better level of confidence in their trustworthiness.
This thesis advances the evaluation of the paper-based voting systems using formal
methods with automated analysis. In analysis of security protocols, the formal
definitions of protocol requirements need to be constructed precisely. To this
end, a formal framework regarding the anonymity requirement has been given
and demonstrated to be appropriate for the analysis of voting systems. Similarly,
it has been demonstrated that the assumptions under which voting systems
are secure should be well-defined for a rigorous security analysis with the automated
analysis of the ThreeBallot voting system. Moreover, a novel approach has
been proposed to analyse cryptographic voting systems under a passive attacker
model using the Prˆet `a Voter voting system as case study. Finally, an active
powerful attacker has been adapted into the analysis of voting systems, and an
automated formal analysis of vVote voting system has been conducted, which is
under development for use in Victorian Electoral Commission (VEC) elections,
Australia in 2014. With the analyses of voting systems performed in this thesis,
the formal approach developed here has been demonstrated to be successful in the
automated analysis of such complex systems using the process algebra, Communicating
Sequential Processes (CSP), and the model checker, Failures-Divergence
Refinement (FDR). |