I've seen at least three independent implementations of this idea. One is called Snap2Pass: http://prpl.stanford.edu/papers/soups10j.pdf http://prpl.stanford.e

I've seen at least three independent implementations of this idea. One is called Snap2Pass: http://prpl.stanford.edu/papers/soups10j.pdf http://prpl.stanford.edu/papers/soups10j.pdf http://www.youtube.com/watch?v=-9QOcDV4VZI http://www.youtube.com/watch?v=-9QOcDV4VZI Here's one called Animate Login with source code: http://animate-innovations.com/content/animate-login http://animate-innovations.com/content/animate-login