Wikipedia:Reference desk/Archives/Mathematics/2017 July 29

= July 29 =

Zero-knowledge proof of valid voting?
Have any election schemes been devised whereby voters would be able to prove they'd cast a valid vote, without having to reveal what that vote was (e.g. to enforce Australia's mandatory-voting law against people who spoil the ballot)? Neon Merlin  01:00, 29 July 2017 (UTC)


 * Under the British voting system, spoilt votes could be traced back to the voter, though as far as I know they never are (unless there is evidence of fraud), because voting is not compulsory here. Do systems in other countries not include some link between voting paper and voter for use in cases of fraudulent voting?    D b f i r s   06:47, 29 July 2017 (UTC)
 * There are some systems created by David Chaum that I think fit your description. See David Chaum. Staecker (talk) 11:10, 29 July 2017 (UTC)


 * In developing nations, it frequently isn't possible to maintain and check a register, so they often employ simpler methods, such as people dipping their finger in ink to show they voted. While you could technically trick people into thinking you voted by dipping in your own ink, of the proper color, they could keep the color secret to discourage this, or make it fluoresce under a certain frequency of UV light, if it was ever a problem. StuRat (talk) 23:44, 29 July 2017 (UTC)


 * But what would be the point of that? What countries absolutely require you to vote?  The only ones that require it and make any attempt at enforcement are places developed enough to maintain a really comprehensive register that would make thumb-inking (and similar manual techniques) completely pointless.  Nyttend (talk) 00:19, 30 July 2017 (UTC)


 * Are you certain there's NO place in the undeveloped world that requires voting ? Could even be a very local level, like a village. Incidentally, even nations with registration systems could use thumb-inking as a backup method, in case their computer database is hacked, for example.  StuRat (talk) 02:57, 30 July 2017 (UTC)
 * , could you say how it works in the UK that spoilt votes may be traced back to voters? If I believe the procedure is to tick a box in a printed paper and put the paper in the urn, so what is preventing you from not ticking any box? (Or are you talking about people who fail to go to the voting booth, not those who spoil their vote?)  Tigraan Click here to contact me 15:48, 1 August 2017 (UTC)
 * The procedure is that a printed voting paper is issued to each individual, and a number is recorded from the counterfoil. The paper containing the vote (or blank or spoilt) is placed in a sealed box which is opened under the supervision of the returning officer, and the votes counted.  The record linking the voting paper to the numbered counterfoil is kept separately, and never linked to voters except in the case of fraud.  My point was that it would be possible to trace those who had spoilt their voting paper or left it blank, and even to trace who had voted for which candidate, but if this was ever done without extremely good reason, then there would be a public outcry and loss of jobs.  By the way, the paper should be marked with a cross opposite the chosen candidate, not a tick.    D b f i r s   20:22, 1 August 2017 (UTC)


 * Side note: a good secret voting system should prevent people from proving they voted for a particular candidate. One of the examples in The Strategy of Conflict involves a voter who, if they could prove how they voted, would be coerced by the mafia into voting for a particular candidate, so the loss of an ability (proving one's vote if one so desires) results in a better result (not being coerced into voting for a candidate one dislikes). (I also had read a paper in French about a voting system in Italy where ballots required the voter to order a large number of candidates in a list, and as a result the ordering of candidates at the end of the ballot - which was of little consequence for the election result - could be used as a signature for the vote as each ballot was read in full publicly, and how mafiosi consequently used the system for coercion; unfortunately, I cannot find the source)
 * While coercion may not be an issue in the OP's original request, it could be, in which case the system should allow one to prove that one voted for a candidate but not to prove which candidate it was. Tigraan Click here to contact me 16:05, 1 August 2017 (UTC)