[EM] untraceable receipts

[Richard Moore]

--- David GLAUDE <dglaude at g...> wrote:
 >
 > Forest Simmons wrote:
 >
 > >>It is not acceptable for the voter to run out of the voting location
 > >>with a receipt. This mean I have something that proof my vote. I 
could
 > >>be forced to show my receipt and if I did not vote as I was asked...
 > >>face the consequence.
 > >>
 > >>The secrecy of the vote make it impossible to have a hardcopy you 
take
 > >>at home!!! Not even a magic number secretly encoded or else.
 > >
 > > What if you were given several receipts, and only you know which 
is the
 > > real one.  One of the fake receipts could be used to satisfy the 
mafia.
 >
 > What was the goal of that receipts???
 > 1) To remember who you voted for?
 > or
 > 2) To verify your vote was counted?
 >
 > 1) is silly.
 > If 2) is possible for you, it is possible for the mafia too. ;-)

As Ernest pointed out, public key cryptography could make (2) possible 
without the need for a plaintext receipt. However, it would still be
possible for shady characters to coerce your vote, and ask you for 
your private key to decrypt the receipt in order for you to avoid 
punishment. Which is where Forest's idea comes in.

In fact each receipt could be a fairly large file that has multiple 
ballots encrypted in it, and you could choose the one you would want 
to display to the criminals. For the intended verification purposes, 
the *real* ballot would have a digital signature that could only be 
verified by the election authorities. And you can verify which of the 
many is really yours by means of a second digital signature, or a code 
word that you designate or remember (e.g., each displayable ballot 
could also display a random dictionary word, and you would remember 
the word associated with your designated ballot).

All this seems too complicated to be practical. Just think of having 
to go in and specify your real vote *plus* the fake one for the crime 
lords. And to keep straight which is which when providing the 
information to the voting machine.

Finally, the "fake receipt with digital signature" scheme falls apart 
when you realize that a clever programmer could have his software sign 
the ballot on your receipt that he/she likes best.

  -- Richard