carpe decorum

Secret Ballots and Verification

How to Build a Better Ballot (PDF) by David Chaum addresses the problem of how to verify votes without compromising the secrecy of the ballot.

From the press release:

The new type of receipt is printed in two layers by a modified version of familiar receipt printers. You can read it clearly in the booth, but before leaving, you must separate the layers and choose which one to keep. Either one you take has the vote information you saw coded in it, but it cannot be read (except with numeric keys divided among computers run by election officials)