The Message Must Get Through
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The year is 300A.D., and you're part of a war machine unlike anything the world has ever seen. You are a field General for the Roman Empire and charged with assimilating yet another non-Roman culture. Your current mission; get tactical information you've collected in the field to an outpost one hundred miles away. The land between you and the outpost is treacherous and filled with enemy. The information you've collected is critical to the success of the current campaign and must reach the remote outpost intact. This will call for ingenious deception.

You send for a messenger, who is in reality a Roman slave. The messenger's head is shaved clean, and the message for the outpost is tattooed on his head. Several weeks later, the messengers hair has grown in and completely concealed the secret information. The messenger departs and one week later reaches the outpost. A quick head shave and the outpost has the information needed to ensure yet another victory for Rome.

This is one of the earliest forms of Steganography on record. The art of hiding messages within another medium and avoiding detection.

The Ancient Technology Of Deception
A Modern Day Threat
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Take a look at the following two images at http://www.defendingthenet.com/stgpic.htm. The first picture is quite normal. The second picture looks exactly like the first. However, the second picture is not a normal picture at all. It contains a portion of the article you are currently reading in the form of a Microsoft Word document. It has been embedded in the image using a Steganography program and is nearly undetectable. Not only can you not see a visual difference in the picture, the file size of the original and the Stego Medium (image with the hidden text) is exactly the same.

There are several programs on the Internet that may be able to detect a small anomaly in the picture, like "stegdetect", but the method used to embed the secret document is protected by a key, or password, as well.

The technology behind effective Steganography is quite complex and involves serious mathematical computations. Computers and technology make this a trivial task and make this art of deception a serious threat to the security of information. Company's that regard their information proprietary, and rely on the security and integrity of their intellectual property, could be at significant risk.

A Real World Example Of Steganography
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Many organizations protect their internal network resources and information by using sophisticated security measures, such as firewalls. Many firewalls can block e-mail attachments such as executables, spreadsheets, and documents, and do so by looking for file extensions. Some security measures, or content filters, can actually determine if the particular file or attachment is actually the type to be blocked, a spreadsheet for instance, by analyzing the contents of the file. This helps prevent the transmission of file attachments that have had their extensions altered or removed.

But how many organizations block the sending of image files like.jpg or .bmp images.

Imagine having someone on the inside of a company who secures a proprietary document. This person then embeds the document into a picture and sends it to an e-mail address on the Internet. The company's defense systems block many types of file attachments, but image files are not considered a risk, so they are allowed through. The sender and receiver previously agreed on the method and type of deception. Using a Steganography package freely available on the Internet the task was easily and securely executed. The company was completely unaware of the fact that important information was leaked.

Conclusion
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There are so many components to this form of deception, I could write ten pages on the subject alone. The purpose for this article is to make people aware of this form of deception and the threat it poses to digital security.

Steganography also has an impact on non-digital information as well. And, pictures are not the only medium that can be used. Sound files are another favorite host for embedding secret information. If you would like to see Steganography in action you can download "The Third Eye" from the following link http://www.defendingthenet.com/downloads/steg.zip. It is a freely distributable Steganography program and was used to create the two image examples referenced above. This download contains the two images above and you will be able to open the image with the hidden text and extract it. The zip file contains a README.TXT file that will give you full instructions on how to extract the hidden text in the image.

But first, you will need the password! Can you guess it? I'll give you a clue: What form of deception did the Roman General use to send his message?**

*The story "The message must get through" although based on documented information about a Roman General performing such an act of deception, is fictional and was written as illustration of such an event strictly for use in this article.

**You should be able to easily guess the password however I must point out that the password should be entered all "lower-case".