Draw a picture on a piece of paper. Sign it, write your name, arbitrary words, whatever. Hold it up to a camera. Could something like this be made to work?

Draw a picture on a piece of paper. Sign it, write your name, arbitrary words, whatever. Hold it up to a camera. Could something like this be made to work? Work in the sense that a variety of cameras could read the same "password"? I guess QR codes have a fair bit of redundancy built-in...