Steganography (also known as Stego) is derived from the Greek word steganos, (hidden or covert), and graphy (writing or drawing). Steganography is basically hiding information in plain sight. Imagine for example, writing with invisible ink. Steganography is another way to protect your information from malicious cybercriminals.

In the past, Steganography was used in the form of documents written in milk or juice (the writing would be revealed only when they are heated), or through microdots (when a large amount of information is shrinked to the size of a dot, used as a punctuation mark).

Modern day Steganography

Today steganography, is used to hide information in computer files. Information can be generally hidden in various file formats, such as images, audio files, text files and Word documents.

However, unlike text documents, where you one may find letters missing, audio and image files can be modified to “hide” data without affecting their original quality too much. In an image, there are always redundant bits of color. Similarly, in an audio, there are low frequency sounds that are not audible to the human ear. These little bits of the image and audio files can be altered to hide information, and still end up with a new file, that is not very different from the original. Unless a person has the original picture or audio file to compare with, it is almost impossible for a casual observer to tell whether there is hidden information in a particular file.

Even with the original file to compare with, it is not easy to spot the difference. Look at the two pictures below. One of them contains hidden information. Which one is it? Click here for the answer.

Although steganography has traditionally been used by the military and governments organizations, there is now big interest shown by companies to safeguard their information from theft. Today, steganography is also used for transmitting information safely and for embedding trademarks in images and music files, for copyright protection (also known as digital watermarking).Back to Jump

Malicious use of Steganography

Just like many other security tools available today, Steganography can also be used for both legitimate and illegal uses.

There is suspicion that terrorists involved in the September 11 attacks might have used steganography for covert communications. Although no such connection has yet been proven, such a concern only highlights the possible implications of steganography for illegal uses.

As a result, there is a need to monitor the use of steganography to curb illegal uses. Steganalysis is the process of detecting steganography. Basically, there are two methods to detect modified files. One way is called the visual attack, which involves comparing a suspected file with the original copy. Although this method is very simple, it is not very effective as, most of the time, you cannot tell or see that the picture has been tampered with.

The second way is by using a statistical attack. Statistical attacks come in many forms. The general idea, however, is to detect changes in patterns of the pixels and the frequency distribution of the colors in a potential stego file.

There are many software available that detect whether any information is hidden in a file.

Back to Jump

Cryptography versus Steganography

Cryptography is very different from steganography. In Cryptography, the emphasis is to jumble up the information in a way such that it is very hard for an intruder to unscramble the information, unless he has the right key. However, in Steganography, the idea is to completely hide the information from a potential intruder; hence, steganography is the art of hiding information in plain sight.

Often, steganography is used together with cryptography for a higher level of security.

Back to Jump

Some software that implement Steganography

You can use the following software to hide your information.

http://www.snapfiles.com/get/stools.html
http://www.spychecker.com/program/stools.html

http://www.dancemammal.com/imagehide.htm

If any of the above links do not work, please proceed to a search engine and search for the above mentioned software.

Back to Jump

Reference

What is steganography? - A Word Definition From the Webopedia
http://www.webopedia.com/TERM/S/steganography.html

Steganography - Wikipedia, the free encyclopedia
http://en.wikipedia.org/wiki/Steganography

Steganography Revealed by Kristy Westphal
http://www.securityfocus.com/infocus/1684

Investigator's Guide to Steganography by Gregory Kipper