From: Hal <hfinney@shell.portal.com>
Date: Tue, 2 Aug 94 07:32:33 PDT
To: cypherpunks@toad.com
Subject: Re: Steganography
In-Reply-To: <Pine.3.89.9408020951.A167-0100000@vulcan.nexor.co.uk>
Message-ID: <199408021432.HAA23712@jobe.shell.portal.com>
MIME-Version: 1.0
Content-Type: text/plain


Andrew Brown <a.brown@nexor.co.uk> writes:

>I'm currently on the look out for new steganography ideas (you might have 
>seen the patches I wrote that allow files to be hidden in gzip compressed 
>files). I thought of a load of obvious stuff like adding/not adding 
>spaces at the end of lines of a text file, carefully choosing assembler 
>instructions where two are available, etc. Has anyone got any more ideas?

One possibility would be to right-justify your  text,  as  a  few
people  like  to  do,  then  to tweak the algorithm for inserting
spaces into lines to depend on the next bits of the embedded mes-
sage.  Generally, you have N spaces to insert into M word breaks.
If M divides N, you don't have any choice, but otherwise you have
N  mod  M  "leftovers"  to  distribute among M.  This would allow
several bits per line.

Hal