From: Sergey Goldgaber <sergey@delbruck.pharm.sunysb.edu>
Date: Sun, 27 Feb 94 20:34:58 PST
To: Matt Thomlinson <phantom@u.washington.edu>
Subject: Re: standard for stegonography?
In-Reply-To: <Pine.3.89.9402271938.A803-0100000@stein2.u.washington.edu>
Message-ID: <Pine.3.89.9402272347.A8795-0100000@delbruck.pharm.sunysb.edu>
MIME-Version: 1.0
Content-Type: text/plain




On Sun, 27 Feb 1994, Matt Thomlinson wrote:
 
> I think these two have a lot to do with each other. Sergeys' suggestion 
> would definitely make it a tougher to pick out a starting place to 
> search for hidden text. However, the message (if it is ever found in the 
> file) points to the intended recipient. This defeats the purpose of 
> "stealth pgp", (which would probably be used in this case to strip off 
> telltale headers and such). 
> 

The hidden message need may be a stripped PGP encrypted file.  It need not
specify who its addressed to!  The intended recipient will be able to 
retrieve the file regardless.  His program should automatically revive 
the file starting from _his_ public-key checksum-value offset (which both 
the sender and the reciever already know, without the need for any 
telltale headers in the file).  Even if the opponent tries all possible 
offsets and filelengths he/she will always get noise, never anything 
pointing to the reciever.

> If you weren't worried about this type of deniability, though, I don't 
> see a problem with it.
> 

It wasn't me!  ;)

> mt
> 
> Matt Thomlinson                               Say no to the Wiretap Chip!
> University of Washington, Seattle, Washington.
> Internet: phantom@u.washington.edu      	    phone: (206) 548-9804
> PGP 2.2  key available via email or finger phantom@hardy.u.washington.edu
> 


Sergey