Security -- The problem with an encrypted message is that it announces, "Hey! Smart guy! Try to crack me."
However, with steganography a message can be embedded in a digital image so that no one knows it's there. Except, of course, the person for whom the message is intended. That person can separate the message from the image with software recently developed by University of Maine engineering professor Rick Eason and Kyushu Institute of Technology professor Eiji Kawaguchi.
While Eason and Kawaguchi's software is new, with patent pending, steganography isn't. The word means "covered writing" and derives from the Greek. One ancient method of concealment was to shave the head of the messenger and tattoo the message on his head. After the messenger's hair grew in, the tattoo would be undetected until his head was shaved again. Modern examples are invisible inks and microdots.
Hiding information among the pixels is not new either. But whereas previous steganographic efforts focused on the least significant areas of an image, which were easy to manipulate without affecting the picture, Eason and Kawaguchi use the most complex, or noisiest, parts of the image where the pixels are densest, thereby making the message that much harder to decode. Just as Waldo, for example, is usually hidden in the busiest part of the picture.
While the military and industrial espionage value of steganography is obvious, Eason envisions other, more benign apps. "You could have a digital photo album," says Eason, a 43-year-old Tennessean who's been teaching at Maine's frigid Orono campus for 11 years. "You could embed notes in the picture: who's in it, what f-stop you used, the date, a personal memory.
"It's also good for ID and smart cards," he continues. "You put a chip on the card; you put a digital image in the chip; you put data in the image -- mom's maiden name, fingerprint information, iris photos. Makes it much harder to forge."
And as for finding Waldo? Forget it.
-- David Rosenbaum