Formally Verified Verifiable Electronic Voting Scheme

Abstract

Since the introduction of secret ballots in Victoria, Australia in 1855, paper (ballots) are widely used around the world to record the preferences of eligible voters. Paper ballots provide three important ingredients: correctness, privacy, and verifiability. However, the paper ballot election brings various other challenges, e.g. it is slow for large democracies like India, error prone for complex voting method like single transferable vote, and poses operational challenges for large countries like Australia. In order to solve these problems and various others, many countries are adopting electronic voting. However, electronic voting has a whole new set of problems. In most cases, the software programs used to conduct the election have numerous problems, including, but not limited to, counting bugs, ballot identification, etc. Moreover, these software programs are treated as commercial in confidence and are not allowed to be inspected by members of the public. As a consequence, the result produced by these software programs can not be substantiated.

In this thesis, we address the three main concerns posed by electronic voting, i.e. correctness, privacy, and verifiability. We address the correctness concern by using theorem prover to implement the vote counting algorithm, privacy concern by using cryptography, and verifiability concern by generating a independently checkable scrutiny sheet (certificate). Our work has been carried out in the Coq theorem prover.