Support STAR voting

[wolftune]

Related to #116 for score voting, STAR voting is a simple but novel combination of score voting and an automatic runoff round. It addresses some of the concerns people have about score and has been evaluated to be the all-around best ballot system by several measures.

ADDENDUM: orgs I'm involved with are specifically interested in using this, so it's more than just theoretically nice…

[benadida]

interesting, could be useful at some point, requires a lot of work.

[str4d]

If additions / changes to the crypto were reasonable, STAR-Vote (which is based on the same approach as Helios) could probably be adapted.

If we restrict this to using the existing cryptography and ballot mechanism, then here's a (probably-insecure) sketch of what it could look like (I'm basing this solely on the existence of a multiple-choice voting option, I haven't looked at the underlying crypto yet):

Election creation:

• Elector defines N candidates, to which each voter will assign a number between 0 and 5.
• Helios creates five identical multiple-choice questions containing all N candidates.
• Helios creates N! single-choice questions, one for every pair of candidates, to handle the possible runoff combinations.
  • This is probably insecure in that there is nothing to bind the multiple-choice answers to the single-choice answers. Maybe there's a way to combine or link them, but I haven't looked at the crypto yet, and hadn't thought through the runoff process when I started writing this comment 😅 Other sketches welcome!

Voting:

• Helios UX shows the STAR UX (N candidates, each with a radio choice from 0 to 5, defaulting to 0 for each candidate).
• Voter updates the radio choices with their desires.
• Helios converts the radio choice into that many checks for the given candidate across the five questions.
• Helios shows the STAR UX in the "review vote" page, maybe with a sub-section showing the underlying Helios question responses it results in (for auditability).
• Voters submit their votes.

Election results:

• The normal Helios question tally figures out the totals per question.
• The Helios UX adds up the totals per candidate across the five questions, and displays the overall totals, from which the two candidates with the highest score can be determined.
• The Helios UX displays the result of the single-choice question corresponding to the runoff between those two candidates.

[jacksonloper]

Yep, @str4d remarks make sense to me. I don't see why, from a security standpoint, this would require much work. There would certainly be some UX to do. It seems like it would be a lot easier than implementing a whole new online voting system, which is what for example the Equal Vote Coalition has ended up doing, not least due to a lack of flexibility in the excellent helios voting systems.

Edit: I do kind of see now, from a security standpoint, it would require some work. I think the browser would have to generate n choose 2 proofs (showing that the derivative "ranking" pseudovotes were consistent with the n 0-5 votes). It could take a bit of nontrivial coding, and then from user's perspective it probably would require a few extra seconds of browser compute.