CISSP: Certified Information Systems Security Professional Study Guide by Gibson Darril & Chapple Mike & Stewart James M

Author:Gibson, Darril & Chapple, Mike & Stewart, James M. [Gibson, Darril]
Language: eng
Format: mobi
Publisher: John Wiley and Sons
Published: 2012-06-13T23:00:00+00:00

Even though TLS has been in existence for more than a decade, many people still mistakenly call it SSL. For this reason, TLS has gained the nickname SSL 3.1.

Steganography and Watermarking

Steganography is the art of using cryptographic techniques to embed secret messages within another message. Steganographic algorithms work by making alterations to the least significant bits of the many bits that make up image files. The changes are so minor that there is no appreciable effect on the viewed image. This technique allows communicating parties to hide messages in plain sight—for example, they might embed a secret message within an illustration on an otherwise innocent web page.

Steganographers often embed their secret messages within images or WAV files because these files are often so large that the secret message would easily be missed by even the most observant inspector. Steganography techniques are often used for illegal or questionable activities, such as espionage and child pornography. However, they can also be used for legitimate purposes. Adding digital watermarks to documents to protect intellectual property is accomplished by means of steganography. The hidden information is known only to the file’s creator. If someone later creates an unauthorized copy of the content, the watermark can be used to detect the copy and (if uniquely watermarked files are provided to each original recipient) trace the offending copy back to the source.

Steganography is an extremely simple technology to use, with free tools openly available on the Internet. Figure 10.2 shows the entire interface of one such tool, iSteg. It simply requires that you specify a text file containing your secret message and an image file that you wish to use to hide the message. Figure 10.3 shows an example of a picture with an embedded secret message; the message is impossible to detect with the human eye.

FIGURE 10.2 Steganography tool

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