It seems pretty simple to me. Have the machine print a receipt that shows your info and who you voted for, have the voter check it over and sign it, and then have the voter hand it in before leaving the voting station. The receipt is really no different than a paper ballot at that point.
That's not to say that other security precautions can be ignored. Ideally I'd think there should be mature open-source software running on secure intranets for each voting station, and transparency at every level of the process, including better transparency in how those physical receipts are transported, handled, and stored.
That's not to say that other security precautions can be ignored. Ideally I'd think there should be mature open-source software running on secure intranets for each voting station, and transparency at every level of the process, including better transparency in how those physical receipts are transported, handled, and stored.