I think we need some kind of Zero-knowledge proof[1]: "a method by which one party (the prover) can prove to another party (the verifier) that a given statement

I think we need some kind of Zero-knowledge proof[1]: "a method by which one party (the prover) can prove to another party (the verifier) that a given statement is true, without conveying any information apart from the fact that the statement is indeed true." In the case of voting, we want to be able to prove that a person voted, with no knowledge of the actual vote. If you can count the number of votes cast that should be enough to be confident in the result. [1]: https://en.wikipedia.org/wiki/Zero-knowledge_proof https://en.wikipedia.org/wiki/Zero-knowledge_proof