In their own words:
Punchscan is a voting system invented by David Chaum that allows voters to take a piece of the ballot home with them as a receipt. This receipt does not allow voters to prove how they voted to others, but it does permit them to:
- Verify that they have properly indicated their votes to election officials (cast-as-intended).
- Verify with extremely high assurance that all votes were counted properly (counted-as-cast).
It uses simple cryptographic techniques to ensure election integrity. The demos on their ‘learn more’ page shows how a voter casts and verifies their vote as well as showing how election integrity can be audited.
After you go through the demos you should also review the excellent FAQ.
The system that is demonstrated can only handle ballots for which there are two candidates for each race. I believe that they have extensions to the system to handle multiple candidates and well as handling
- alternate voting systems
- improved support for disabled voters
- write-in candidates
So it ready for prime-time use?
I don’t know. It has only been used for a few elections and is a very new system so I suspect that it is not ready for wide deployment.
If you are interested in following the development and deployment of punchscan you can join their mailing list.