Software will look for lurking messages

March 17, 2005
A University of Delaware research team is developing techniques to detect messages hidden in apparently ordinary digital images and videos.

Researchers have high hopes that this process, called steganography, will help combat terrorism.

The fear is that terrorist organizations are using electronic steganography to pass vital information surreptitiously through images posted on the Internet or sent via e-mail.

"The work we are doing is in multimedia, with a focus on digital images," said Charles Boncelet, UD professor of electrical and computer engineering. "You can take an image on your Web site and use steganographic techniques to hide a message in the image. The image looks completely ordinary but if you know the key, you can extract the secret message." The object of the research is to try to figure out how to find steganography in the images.

Steganalysis is difficult because the messages are hidden by design. When you hide a message in a digital image, you change the image slightly. Changing the image too much gives away the ruse. The steganalyst is at a disadvantage because he does not have the benefit of the original for purposes of comparison.

Boncelet's approach is to use fast computer algorithms that look for unusual features in the image. In addition to the research, the project will provide training in steganalysis and intelligence techniques.

After the terrorist attacks of Sept. 11, 2001, there was widespread speculation in the public press that terrorists had used steganography on the Internet to communicate plans. Although those reports were never confirmed, the possibility remains a grave concern.

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