From: John Young <jya@pipeline.com>
Date: Mon, 19 Jan 1998 08:34:18 +0800
To: cypherpunks@cyberpass.net
Subject: CAD Stego
Message-ID: <1.5.4.32.19980119003138.006cc150@pop.pipeline.com>
MIME-Version: 1.0
Content-Type: text/plain



This repeats a suggestion from 1994 about using computer
assisted design programs to conceal text or other data:

1. CAD uses vectors to make graphics, including text,
and most programs can import a wide variety of data from 
other formats.

2. Several features can manipulate CAD objects into
unrecognizable forms by modifying scale, dimension,
orientation, opacity and so on.

3. The scale feature is useful to reduce, say, a text
of any length, or any digital object, to the size of a pixel. 
This pixel can be located, say, under a visible line, or, be 
made transparent as a "phantom" object. (An engineer
"stipples" concrete with microdot exotica and lofts the docs
to the Saudis, getting paid ten times the regular fee.)

4. Or, the text can be distorted by scale and dimension
to appear to be a line serving another function.

5. It's a snap to encrypt the text and import
it into CAD via several programs that do that duty.
Then the message could be distorted or hidden as
described above, for piggy-backing on an innocent-
looking document issued, say, to GSA for replenishing
the Blanco Bunker, where it would be opened by the
cp insider-sou-chef for de-distorted, decrypted 
instructions on how to prepare and place the bean.

6. To be sure, the underlying CAD code of the ciphertext 
could be identified by an astute auto-message-vetter of the 
EOP and then the CADbreakers would be beckoned to 
the roachtrap.

7. Big shortcoming: how to securely transmit the location 
(virtual coordinates) of the hidden message and what 
modifications need to be reversed for message access.
Beware of using 0,0,0 -- a near-universal data point for
CAD docs. However, 0,0,2^50 miles might be overlooked
if the 3d view is disabled.

8. Medium shortcoming: Full-featured CAD programs are 
expensive, however, the popular lite versions are cheap
and can usually read the pricier output.