Re: Steganography

From: Mikael Johansson (
Date: Wed Sep 26 2001 - 13:29:16 MDT

> On Tue, 25 Sep 2001, Harvey Newstrom wrote:
> > How did I do? Was I able to detect a file that had an "undetectable"
> > message in it?
> Yes. As I said, the first one was easy. The first message had a 512 byte
> random payload straight out of /dev/random. The second message had a
> single cr for payload (outguess won't let you add zero length files).
> Next step would be to use same approach on pictures of different origins
> and quality. Large pictures with low compression rate.
> The step after that would be telling /dev/random from an encrypted
> message. Still game?

Try it: I have taken Anders' most magnificient raytracing 'seshat.jpg', and
produced 5 versions of it.

One plain copy of the image
One with a plaintext message steganographed with outguess
One with that message, encrypted with pgp and steganographed with outguess
One with that message, encrypted and steganographed with outguess
One with pure random data (dd if=/dev/random of=sample.bin bs=512 count=1),
steganographed with outguess.

You can find them at

The challenge is to pair the pictures with their respective 'descriptions'.

Good luck :-)

> -- Eugen* Leitl <a href="">leitl</a>
> ______________________________________________________________
> ICBMTO: N48 04'14.8'' E11 36'41.2''
> 57F9CFD3: ED90 0433 EB74 E4A9 537F CFF5 86E7 629B 57F9 CFD3

// Mikael Johansson

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