From: Bruce Zambini <jlasser@rwd.goucher.edu>
Date: Fri, 1 Mar 1996 10:53:50 +0800
To: Bill Stewart <stewarts@ix.netcom.com>
Subject: Re: Simpler solutions (was Re: Stealth PGP work)
In-Reply-To: <199602290844.AAA03851@ix4.ix.netcom.com>
Message-ID: <Pine.SUN.3.91.960229162811.6796B-100000@rwd.goucher.edu>
MIME-Version: 1.0
Content-Type: text/plain


On Thu, 29 Feb 1996, Bill Stewart wrote:

> At 10:26 AM 2/28/96 -0500, Bruce Zambini wrote:
> >Or, you can develop a public-key stego system...
> >ie a stego system that uses bits in specific ways depending on the 
> >private key of the recipient.
> I assume you mean the public key of the recipient?

Well, no.  Or yes and no. Something like Public-Key crypto in general, 
where the public key isn't enough knowledge to decrypt it.  For example, 
you could encrypt a session key with RSA.

[...]
> You gain a certain degree of obscurity by using
>    stego(picture, scramble( PGP(message, pubkey), key ))
> where scramble is some cheap symmetric encryption algorithm and 
> key is either the recipient's public key or keyid, and PGP is in binary mode.
> This hides the message from eavesdroppers who don't know the recipient,
> but not from eavesdroppers who are willing to test against the keys
> of a list of usual suspects (assuming the recipient is one of them.)

Well, that's what I want to avoid; I think the issue is that as long as 
stego is predictable, there's a problem, ie a message to a certain party 
can be shown to exist, even if it's not readable. This might prove more 
than ample evidence in certain circumstances.

You shouldn't be able to recover the stego'd message without special 
knowledge.  This isn't addressed by current software, to my knowledge.

Jon Lasser
----------
Jon Lasser (410)494-3072                         - Obscenity  is a crutch  for
jlasser@rwd.goucher.edu                            inarticulate motherfuckers.
http://www.goucher.edu/~jlasser/
Finger for PGP key (1024/EC001E4D)               - Fuck the CDA.