Congratuations are in order to Luis von Ahn, winner of the 2006 John D. and Katherine T. MacArthur foundation fellowship. Luis won this honor in his work concerning steganography.
The definition of steganography (from wikipedia):
Steganography is the art and science of writing hidden messages in such a way that no one apart from the intended recipient knows of the existence of the message; this is in contrast to cryptography, where the existence of the message itself is not disguised, but the content is obscured.
While this gentlemen might not be a household name to many of us, anyone who has participated on the modern internet has most definately seen the outcome of his work.
He and his colleagues created “CAPTCHA“, a method of validating that a human is interfacing with a webpage (among other things). (Completely Automated Public Turing test to tell Computers and Humans Apart) CAPTCHA presents an image with random text created in an image format. The code within CAPTCHA image is known to the server where the data is being sent to. If the message is the same as the one submitted, then the server trusts that the data was submitted by an entity that passes the turing test.
Again, congratutations to Luis von Ahn for his work.
Read the article here.