Visual cryptography

Josh Benaloh mentioned Visual Cryptography in a talk last week. I had no idea what that was, so I did a quick investigation.
It turns out visual cryptography is a secret sharing scheme where no computer is needed for the decoding. Instead, a human can extract the secret by combining the parts visually. A common example for parts is black and white patterns printed on transparencies.
It supports threshold schemes, where the secret information isn't revealed or recovered unless a minimum number of parts are put together.

Links:
Original visual cryptography paper from Moni Naor and Adi Shamir (1995).
Wikipedia's page on the topic.
Here is a good pdf overview from Kristin Burke.
Doug Stinson's Visual Cryptography Page.
Some visual cryptography introduction, examples and software.

I just noticed that you linked to one of my college presentations in this entry. Neat! Thanks for the ego-boost on a slow Friday :)

Kristin