You just gave me an interesting (but somewhat unrelated) idea. You can "sign" a timestamp by appending a hash of that timestamp with some sercre value. This wa

You just gave me an interesting (but somewhat unrelated) idea. You can "sign" a timestamp by appending a hash of that timestamp with some sercre value. This way, whenever the user submits your form, you can reliably determine when it was requested without storing anything on the server.