Paper is the only current option. However a secure voting system isn’t that hard either. There are numerous proposals that would work, transition would simply be difficult. But it’s not even necessary, simple is better for something like this and there’s nothing wrong with paper ballots. You just have to distribute the operation of verifying better. Simple proof is a great example of how good it could be 

 Hmm. Slight update. 

The voting machines that I installed were just electronic counting machines. We still use paper ballots. But the machines do the counting.

Honestly I swear that the machines installed are still used today to do the counting. They look exactly the same on the outside at least.

Do fully electronic ballots exist? I could Google this I guess 😂