KentuckyFC writes "Steganography is the art of hiding a message in such a way that only the sender and receiver realize it is there. (By contrast, cryptography disguises the content of a message but makes no attempt to hide it.) The central problem for steganographers is how much data can be hidden without being detected. But the complexity of this problem has meant it has been largely ignored. Now two computer scientists (one working for Google) have made a major theoretical breakthrough by tackling the problem in the same way that the electrical engineer Claude Shannon calculated the capacity of an ordinary communications channel in the 1940s. In Shannon's theory, a transmission is considered successful if the decoder properly determines which message the encoder has sent. In the stego-channel, a transmission is successful if the decoder properly determines the sent message without anybody else detecting its presence (abstract). Studying a stego-channel in this way leads to some counter-intuitive results: for example, in certain circumstances, doubling the number of algorithms looking for hidden data can increase the capacity of the steganographic channel"