So open it to the public. After the election, publicly associate each password to a vote; also make people register for passwords and keep track of the number o

So open it to the public. After the election, publicly associate each password to a vote; also make people register for passwords and keep track of the number of people who register. Then after the election ask people to check that their password is associated with the vote that they made. Even if only a fraction of voters do so, it would be hard for any potential vote rigger to tamper significantly with the process. And on further thought, it would be better to use public-key cryptography than plain passwords -- get people to encrypt their vote with their private key -- because then the public keys could be released before the election and it could be verified that there are the same number of keys and registered voters. This would be dramatically more secure than the current system.