The way a cash register rolls off a numbered receipt for the buyer, the voting machine should duplicate it for the voter.
Keep the original with the voting officials and give the duplicate to the voter.
If there is any questions publish the original on the web and in a newspaper. The voter could locate their number and compare them.
If there is any differences, notarize the voters copy and surrender it to the officials for investigation.
no, No, NO!
The voter must NEVER be allowed to leave the polling location with any physical proof of how they just voted. That takes us back to the days when political party 'block captains' would ensure that you voted the 'correct' way to gain the favors of those who were (and wished to remain) in political power.
"Hey there, Bob. Let's just get a quick copy of your ballot receipt, just in case there are any election problems, this will help our party prove its case in court... Glad to see you support our party candidates across the board, this is democracy in action. By the way I've heard from the Representatives staff that that your zoning variance will be granted next week..."
It also makes it easy to make election a 'joke' as in any close election just tell everyone to bring their 'notarized' copy in to confirm the winner of the very close election. So I guess that if someone misplaces their copy of their vote(s) then they are just out of luck?
Optical scan, or electronic voting with self-contained paper backup is just fine. Pure DRE with no paper backup is an invitation to future fraud...
dvwjr