Russian Spies' Use of Steganography is Just the Beginning

In this case, the spies were embedding messages in images that were then uploaded to public websites. The messages weren't encrypted - just invisible to the naked eye; lost in the endless stream of communications transmitted daily through the web.

Indeed, it's so easy to write a steganography program that Jon McLoone, head of international business and strategic development at Wolfram, wrote one in Mathematica with just a handful of lines of code. He helpfully points out that his version, unlike the one the spies were using, isn't likely to crash.

The beginning

But this is just the beginning: the principles of steganography can be applied even to continuous communications, such as conventional wireless networks. Using this approach, Krzysztof Szczypiorski and Wojciech Mazurczyk figured out how to pour up to a megabyte per second into an open wireless network.

Steganography can also be implemented in sound files and VoIP protocols. Here's a scenario from Stegano.net, the leading site on steganography: "An employee of an electronic equipment factory uploads a music file to an online file-sharing site. Hidden in the MP3 file (Michael Jackson's album Thriller) are schematics of a new mobile phone that will carry the brand of a large American company. Once the employee's Taiwanese collaborators download the file, they start manufacturing counterfeit mobile phones essentially identical to the original--even before the American company can get its version into stores."

The wasted or less-essential bits in any communication

Steganography works because it's possible to hide secret data in all the wasted or less-essential bits in any communication. All files have what are known as least significant bits - they're the part of any binary number that, when lost, does the least to change the value of the value it represents. (By analogy, the least significant digit of decimal integer 43.218 is 8, and if you lose it you've hardly changed the value of that number for most purposes.)