Friday, October 24, 2008

A Really Secret Ballot

ACM TechNews highlights a voting and encryption article in The Economist about the search for a way of voting that is both reliable and trustworthy. Encrypting people's votes might achieve some trustworthiness.

Dr. Peter Ryan, computer scientist at the University of Newcastle upon Tyne in England may have found one way of doing this. Ryan calls his development "Pret a Voter". The gist of his approach is that paper ballots are used that are in two halves. The candidates' names are on one side and the the tick boxes are on the other. The voter ticks the boxes he wants and divides the paper, putting only the half with the tick boxes on it in the ballot box. The ballots are then scanned by optical reader. The 'trick' part is that the candidates are listed in random order on each ballot paper.

While anyone looking at the deposited half of the ballot paper cannot determine in whose interest the votes were cast, the machine can because each deposited half also carries a cryptographic cipher containing the candidate order on that particular ballot.

A second approach elaborates on Ryan's system. Ben Adida and Ron Rivest, of the Massachusetts Institute of Technology, have created what they call "Scratch & Vote". The ballot paper looks the same as that used in Ryan's 'Pret a Voter', but with an additional scratch-off area that acts as an extra level of security.

David Chaum, a computer scientist and cryptographer who, among other things, invented the idea of digital cash, has created a third idea called Scantegrity II. In this approach, a voter fills in an oval-shaped space instead marking an 'x' next to a candidate's name. With Scantegrity however, the voter uses a special pen whose "ink" reacts with a pattern of two chemicals that has been printed inside the oval-shaped space.

While none of these solutions has been widely tested yet meaning American voters will not see them in process for this election, there is a good chance they will be offered in the next election, especially if scandals emerge in the coming election.

For details on the 3 approaches, see full write-up in The Economist.