Spy trick hides messages in plain sight
In a move likely to thrill conspiracy theorists and government spooks, scientists from Rensselaer Polytechnic Institute are testing the limits of illicit messages hidden inside everyday communications, such as photographs, videos and newspapers.

“If you open up the communication and it looks just fine, that’s a successful communication,” said Jeremiah Harmson, who did most of the calculations while working on his doctorate at RPI and now works at Google. “But if you can’t read it or it just looks suspicious, then you have failed.”

This practice, called steganography, is the flip side of cryptography. In cryptography, everyone involved knows a message has been sent. What’s not known — except to the decoder — is the content of the message. From WWII-era Enigma machines to modern-day computer bit encryption, a lot of effort has gone into devising new ways of cracking these codes.

Steganography hides the fact that a message was even sent, usually by hiding it in plain sight. In the movie “A Beautiful Mind,” the main character, played by Russell Crowe, becomes convinced that the Communists are hiding messages inside news stories and loses his mind trying to decipher them.
[link to waronyou.com]