Coded Communications
In today’s digital world, steganography-from the Greek for “covered writing”-has become a popular form of encryption. Traditional ciphers give themselves away because they appear to be gibberish, and anyone who intercepts them will at least have reason to suspect the sender’s motives. But steganography hides the message inside an ordinary-looking objects such as a digitized photo or sound file. It is “visible” only to someone who knows it’s there. Thus, photo agencies use it to create digital “watermarks” for their pictures....