Introduction and Goals

Social/Ethical Issues


Project Details

Evaluation and Conclusion


Project Details

Modern steganographic methods include embedding electronic communications, such as a text message or an image, within another text message or image. Additionally, the message can also be encrypted to further conceal its content. For a successful encoding, a good cover medium must be utilized. For electronic steganography over the Internet, images are good candidates for cover medium. This is because a cover medium must contain enough information to hide the underlying message while subsequently not appearing to have been modified. It is also desirable for the cover medium to be common enough so as to not attract attention. Images on the Internet are both ubiquitous and can be created to contain enough cover information to hide the underlying message.

A simple example of using images to steganographically hide a message is to modify the least significant bits of an image to encode the message. By modifying the least significant bit, the original image and the modified image appear identical to the human visual systems. The altered image can be sent via email to the intended recipient or posted on web sites for recipients to download. Only persons who have knowledge of the hidden message will be able to decode and recover it. Although this method appears to work well, a simple statistical analysis of the image will usually reveal that additional information is hidden within it.

This simple form of steganography is what we employed when we went about creating our program. We allow the user to specify an input image and a text file containing the secret message and then the program combines the two and outputs another image that is virtually indistinguishable from the original.

In recent years, more sophisticated techniques of steganography have evolved, specifically for the purpose of defeatin most standard methods of detecting steganography. These involve analyzing the image prior to embedding the message to determine its statistical properties. By locating redundant bits of an image and probabilistically replacing the redundant bits with new information, one can defeat most basic statistical analyses. In addition, by subsequently modifying other portions of the image, one can recreate the "statistical" footprint of the original unmodified image that can thwart most attempts at statistical analysis.

If we had the time we would investigate ways of adapting our program to circumvent these detection schemes but due to time constraints and the success of our first iteration we decided to stop here. If wanted, there are many freeware steganographic tools are readily available on the Internet. Most of these have easy to use point and click interfaces that enable a user to quickly encode information. Steganographic tools available on the Internet range from "StegFS" a free steganographic file system to Windows based tools such as "S-Tools", OutGuess, JSteg and JPHide to embed information within images.

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