Interesting voting protocol from Ron Rivest:

Abstract:

We present a new paper-based voting method with attractive security properties. Not only can each voter verify that her vote is recorded as she intended, but she gets a “receipt” that she can take home that can be used later to verify that her vote is actually included in the final tally. Her receipt, however, does not allow her to prove to anyone else how she voted.

The new voting system is in some ways similar to recent cryptographic voting system proposals, but it achieves very nearly the same objectives without using any cryptography at all. Its principles are simple and easy to understand.

In this “ThreeBallot” voting system, each voter casts three paper ballots (with certain restrictions on how they may be filled out, so the tallying works). These paper ballots are of course “voter-verifiable.” All ballots cast are scanned and published on a web site, so anyone may correctly compute the election result.

A voter receives a copy of one of her ballots as her “receipt,” which she may take home. Only the voter knows which ballot she copied for her receipt. The voter is unable to use her receipt to prove how she voted or to sell her vote, as the receipt doesn’t reveal how she voted.

A voter can check that the web site contains a ballot matching her receipt. Deletion or modification of ballots is thus detectable; so the integrity of the election is verifiable.

The method can be implemented in a quite practical manner, although further refinements to improve usability would be nice.