Sunday, July 04, 2010

Steganography appears before our eyes

There’s an interesting report here in the Christian Science Monitor about those (alleged) Russian spies arrested in America using steganography:

The alleged Russian spies recently arrested by the FBI are accused of encoding messages into otherwise innocuous pictures, marking the first confirmed use of this high-tech form of data concealment in real life, experts say.

The accused spies posted the seemingly mundane photos on publicly accessible websites, but then extracted coded messages from the computer data of the pictures, according to the criminal complaint filed by the FBI. Although computer scientists have theorized about the existence of this communication technique for over a decade, this is the first publicly acknowledged use of the technique.

A good explanation of the technique follows:

To generate the picture on a computer screen, the computer assigns every pixel three numeric values that correspond to the amount of red, green or blue in the color the pixel displays. By changing those values ever so slightly, the spies could hide the 1’s and 0’s of computer language in the picture’s pixel numbers, but without altering the picture’s appearance to the human eye, Bellovin said.

When this was first widely discussed a decade or so ago, it did strike me as a particularly clever idea, and the growth in online photo sharing sites since then must make the number of places coded photos could be sitting there waiting to be read by the right person ridiculously large.

What’s more, it’s not as if the software to do it is particularly hard to find.  If you search Sourceforge, quite a few different open source programs for it are available.

It’s all so James Bond, I only wish I had a dire secret and someone to share it with.

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