Steganography is the art of concealing private or sensitive information within a carrier that for all intents and purposes, appears innocuous. It comes from the Greek words steganós (covered) and graptos (writing). Simply put, if you were to view the presented information, it would appear to be something that does not warrant further analysis due to the fact that it does not LOOK or SOUND like anything that contains sensitive information. Steganography has been used for hundreds of years as a means of concealing information from prying eyes before ultimately reaching its intended destination. Examples of its use in history are detailed in the following section The History of Steganography. It relies on the sender and receiver agreeing upon the method by which the information will be hidden and therefore some means of prior communication is essential for steganography to be of any use. Steganography is sometimes confused with cryptography. Although the two can co-exist as discussed later in this document, they are not the same. Both are used to protect information but steganography is concerned with concealing information thereby making it unseen while cryptography is concerned with encrypting information thereby making it unreadable.
Steganography relies on the fact that the human senses are inadequate when compared to analysis performed by machines or even in fact the senses of other animals of the earth. The human eye or the human ear cannot detect very subtle or minute changes in visual or aural presentations making steganography an effective means of concealing private information. One major factor in steganography is that it relies on the fact that a person does not know that a picture or a sound file or a block of text actually contains hidden information. It is a much more effective means of protecting information if the attacker (unintended or unauthorized recipient of information) does not know that the material presented before them
References: 1. Kipper, Greg “Investigator’s Guide to Steganography” Auerbach Publications, 2004 2. Fridrich, Goljan, Du. “Reliable Detection of LSB Steganography in Color and Grayscale Images” http://www.ws.binghamton.edu/fridrich/Research/acmwrkshp_version.pdf 3. Zollner, Federrath, Klimant, Pfitzmann, Piotraschke, Westfeld, Wicke, Wolf. “Modelling the security of steganographic systems” Paper presented at the 2nd Workshop on Information Hiding – April 1998, Portland. 4. Cole, Eric. “Book Excerpt: Hiding in Plain Sight” Published on Computerworld August 4th 2003. http://www.computerworld.com/printthis/2003/0,4814,83714,00.html 5. SpyHunter “Steganography & Steganalysis” Presentation made at Infosec 2004 Conference 6. Petitcolas, Fabian Anderson, Ross J Kuhn, Markus. Attacks on copyright marking systems, in David Aucsmith (Ed), “Information Hiding – A Survey”, Second International Workshop, IH’98, Portland, Oregon, U.S.A., April 15-17, 1998, Proceedings, LNCS 1525, Springer-Verlag, ISBN 3-540-65386-4, pp. 219- 239. And Fabien A. P. Petitcolas. Watermarking schemes evaluation. I.E.E.E. Signal Processing, vol. 17, no. 5, pp. 58–64, September 2000.