From: "Mark M." <markm@voicenet.com>
Date: Fri, 6 Sep 1996 19:37:09 +0800
To: makofi <cypherpunks@toad.com
Subject: Re: Steganography -- Tell Tale Signs?
In-Reply-To: <199609050421.VAA21428@sirius.infonex.com>
Message-ID: <Pine.LNX.3.95.960905184816.709A-100000@gak>
MIME-Version: 1.0
Content-Type: text/plain


-----BEGIN PGP SIGNED MESSAGE-----

On Wed, 4 Sep 1996, makofi wrote:

> 1) If I hide some PGP encrypted data in a
> gif, jpg or wav file will there be any tell tale 
> signs to the naked eye of an expert? If yes,
> what are they?

I don't think so.  Especially for jpg which uses a lossy compression scheme.
Any random noise could be attributed to the compression.  There is already
enough noise in wav files that inverting one bit won't make much of a
difference.

> 3) Are there any tools at the moment 
> to expose (not crack) the hidden encrypted 
> data? If none. are there tools in development?

The whole point of steganography is plausible denial.  The data that someone
could de-stego from a file should just be random garbage, in which case there
would be no way of telling whether there was an encrypted file stegoed in the
data file.  If PGP files are used, a utility like Stealth is a must.

- -- Mark

PGP encrypted mail prefered.
Key fingerprint = d61734f2800486ae6f79bfeb70f95348
http://www.voicenet.com/~markm/

-----BEGIN PGP SIGNATURE-----
Version: 2.6.3
Charset: noconv

iQEVAwUBMi9aFCzIPc7jvyFpAQFyUggAkBekMcImimtOOtXMavb+YFj6uNLnlgKu
leuX37PwQn9ROHjYBiZvhLpTWo8vn5cATI6apN0HUHW81Iy9bss67KkWY/x1tb34
qqR1KMYpEF8MexyiqKxFkOC9Zy/OcufPFIauV2TVlxPXY9m6whH8LPLV81EMYB0M
kAYLGfbDkgQFEgP8prm7AAqArSL7jt80t6OQWOVJU4CebBK5P0onR+9tujhyxrdX
N/GjpeW4cIdn+C3pW6bdxlwgRne9b9dAPcbEeLCOhFwnhBtO1tvg+OyKzPrmVuEh
OaKBwfwSRiGbBCaGv9EXmTIxEGqFfFGioEhRwwCvKsL9JW3NZevSKg==
=CuOh
-----END PGP SIGNATURE-----