Steganography- Hiding Information Inside of Information

by Wayne Porter

Steganography is the art and science of writing hidden messages in such a way that no one apart from the intended recipient knows of the existence of the message. While commonly thought of as messages hidden in pictures it is not limited to just pictures, although this is one the common uses, but messages can be embedded in any number of digital media types. It can even be embedded into sound files.

This practice of  steganography is often called stego for short. Usually a steganographic message will appear to be something else: a picture, an article, a shopping list, or some other message - this is referred to as the covertext or in the case of digital file- the carrier.

I is important to understand that steganography is very different than cryptography and the two are often confused.  With cryptography, encryption is the process of obscuring information to make it unreadable without some type of special knowledge. In this case the message is not concealed just scrambled or obscured.

The obvious advantage of steganography over cryptography is that messages do not attract any attention. A coded message that is unhidden, no matter how strong the encryption, will arouse suspicion and may in itself be problematic.  For example, in some countries encryption is illegal. Stego may even be mixed with encryption so the carrier file actually carries a message that is encrypted. So even if intercepted, another barrier is presented in trying to break the encryption.

A common form of steganography is the use of JPEG files (a computer image) to hide the message. A JPEG (pronounced JAY-peg) is a commonly used standard method of lossy compression for photographic images. The file format which employs this compression is commonly also called JPEG; the most common file extensions for this format are .jpeg, .jfif, .jpg, .JPG, or .JPE although .jpg is the most common on all platforms. Research is already underway to create systems that can detect secret files or messages hiding within digital images.

Electronic images, such as jpeg files, provide the perfect “cover” because you can find them everywhere on the Internet. Even on your own machine it probably contains hundreds if not thousands of jpeg images. These images are shared and they can be posted on Web sites or e-mailed anywhere in the world. Steganographic  techniques allow users to embed a secret file, data, or  a "payload", by slightly shifting the color values to account for the “bits” of data being hidden. The payload files can be almost anything from illegal financial transactions, off-shore account information, terrorist communications, stolen corporate data, criminal messages and even worse- child pornography. The Ames Laboratory has been conducting research using advanced statistics to try to discern between harmless images and ones that hold hidden, and potentially dangerous data.

Curious users can also try stego software, but use at your own risk. You should be sure it is legal to use in your country. In some countries this type of software is illegal and carries stiff penalities for use. However stego itself isn't bad- like any technology it is how it is used.

Find below a sample list of Stego software you can use or try in your own privacy experiments:

• Steganos Security Suite: Trialware. $69 to Buy. Offers a complete encryption software package, which provides protection for users of PCs and laptops. The software features 256-bit AES encryption of an unlimited amount of data; e-mail encryption; the ability to use USB sticks as rewriteable mobile safes; the potential to track down a lost or stolen laptop; track shredding,  a password manager; password quality control; a file shredding; and steganographic capabilities.
  
• Dound's Steganography: Freeware. This software allows users to encode and decode messages of their choice with a keyword. The message is coded into a picture, which can be sent via e-mail, uploaded, and so on, and then decoded by the recipient with the keyword that it was encoded with. It's easy to use and you can't tell the difference between the original and the encoded pictures. It comes with a test picture, too.
  
• Steganography: Trialware. This application enables you to use digital data hiding techniques to hide as well as encrypt files within other files such as picture or sound files. This allows you to encrypt sensitive information, while at the same time hiding it in a file that will not look suspicious, so nobody even knows that there is encrypted information.

This article is copyright 2005 by XBlock.com.
It may not be reprinted or copied without the express written consent of the author.

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