It's a difficult problem because easy proof of who you truly voted for is not desirable (it makes it easier to use money or intimidation on individual voters.)

It's a difficult problem because easy proof of who you truly voted for is not desirable (it makes it easier to use money or intimidation on individual voters.) The old Schneier crypto bible had an interesting introduction to trying to create the right properties to prove things in aggregate without revealing individual votes. It is certainly very interesting but hard to setup in a way where anyone who develops the expertise can independently inspect the properties of an election.