The word “Steganography” is from the Greek meaning “covered, or hidden writing”. Generally, a steganographic message will appear to be something else: a picture, a report, or some other document. The advantage of steganography over cryptography alone is that messages do not attract attention to themselves. A visible coded message, no matter how unbreakable, will arouse suspicion.
A steganographic message in plaintext is first encrypted, and then a covertext is modified to contain the encrypted message. The recipient can recover and decrypt it if he knows the techniques used to conceal and encrypt the hidden message.
Stories of terrorists using steganographic messages began with USA Today articles written by Jack Kelley, who was fired in 2004 for fabricated stories and inventing sources. Private Investigators have far more mundane uses for steganography.
Steganography is used for “Watermarking” which has taken on a new importance in the digital era. Digital images, video, and text, are all easily copied and illegally distributed. By embedding identifying information in a file, steganography software enables Investigators to control the distribution of, and to verify ownership of their digital information. It essentially conceals copyright and distribution information within digital information. One easy-to-use program for this purpose is wbStego.
However, beware that the more important the steganographic message, the more likely someone will try to remove it. StirMark and other software may remove copyright information from files.