PunchScan: The First Truly-Practical Voter-Verifiable Election System

David Chaum
DigiCash Inc.



ABSTRACT:

So-called encrypted vote election systems have held promise for a far higher standard of elections that would allow voters to verify that their votes are correctly included in the final tally -- no matter if those running the election were to try to cheat even with unlimited computing power. Previous approaches to realizing such encrypted-vote systems, however, used touch-screen computers, costly special hardware, and sophisticated cryptography that was difficult to explain widely.

PunchScan adapts the encrypted vote concept to optical-scan ballots and achieves a quite practical, scalable, low-cost, easy to use and understand system. Moreover, it work over the whole range of public- sector voting environments: -provisional ballots allow voters to choose the polling place they wish to vote from; -absentee mail-in ballots have the same high integrity standard as attendance voting; polling places with automation, or where automation has broken down, use the same ballot form and provide similar properties; and considerably more voter disabilities are accommodated than currently while providing privacy and indistinguishability of such ballots. Resistance to improper influence such as vote buying and coercion is provided. Privacy is improved over other systems with automation at polling places and even over what has been achieved by the sophisticated cryptography of earlier systems. Hardware is off-the-shelf, software open source, and online audits allow everyone to verify the full proof of correctness of the outcome.

The system has been realized by a student team and is being used for University of Ottawa student government elections this week!