There are many design goals for an e-voting system. My question concerns a conflict between 2 particular goals:

* A voter should be able to verify that their vote was correctly tallied
* A voter should not be able to prove *how* they voted (to prevent vote selling)

I've looked into various e-voting systems and none of them appear to be able to satisfy these 2 goals simultaneously.

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> Some researchers argue that end-to-end auditability and receipt-freeness should be considered to be orthogonal properties. ([Wikipedia](https://en.wikipedia.org/wiki/End-to-end_auditable_voting_systems))
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Is this an unsolved problem?