I was thinking of something a little more cryptographically secure.

In that case, you would vote, and when you were done, you'd get a paper receipt with a bunch of seemingly random digits (or a barcode version of the same). Later on, you could type those numbers into your computer, press the "verify" button, and get a message saying that, yup, your votes are in there, but we still can't confirm who you voted for.

Maybe you can do better than that, but not by much. Compare that to the confusion among voters trying to make sense out of these receipts and I don't think it's worth the bother.