Doctoral defence: Kristjan Krips “Privacy and coercion resistance in voting”

Remote voting systems, like postal voting and remote online voting, highlight these issues as votes are cast in an uncontrolled environment. Therefore, we studied how different online voting systems attempt to bridge the gap between coercion resistance and verifiability. It turns out that most of the studied online voting schemes rely on non-trivial assumptions to protect voters against coercion.

Regardless of the used anti-coercion measures, it is difficult to protect voter’s privacy if the vote is cast in an uncontrolled environment. However, researchers have shown that vote privacy can also be violated in paper-based voting systems. We built and tested two new proof-of-concept attacks that target vote privacy in paper-based voting systems. These attacks rely on one or more microphones being placed at the voting booth, allowing the sound of filling in the ballot to leak information about voter’s choice.

Similarly to many other voting systems, the designers of the Estonian i-voting system also had to find a balance between coercion resistance and verifiability properties. As a consequence, compromises had to be made. We studied the Estonian i-voting system to identify the security issues related to the voting and vote verification protocol. As a result of the analysis, we proposed possible improvements to the Estonian i-voting system.

As the final contribution, we analysed whether a smartphone-based voting application would introduce new security risks.