From: Matt Thomlinson <phantom@u.washington.edu>
Date: Wed, 23 Feb 94 20:54:10 PST
To: Sergey Goldgaber <sergey@delbruck.pharm.sunysb.edu>
Subject: Re: STEALTH OCEANS
In-Reply-To: <Pine.3.89.9402232236.B2157-0100000@delbruck.pharm.sunysb.edu>
Message-ID: <Pine.3.89.9402232030.A25029-0100000@stein3.u.washington.edu>
MIME-Version: 1.0
Content-Type: text/plain


On Wed, 23 Feb 1994, Sergey Goldgaber wrote:

> No, no.  The function of Stealth PGP is, as I understand it, to simply 

correct. I was commenting on the ability of the stealth-pgp to create 
output not associated with PGP; I didn't mean to imply that s-pgp would 
be designed to do the deletion on its own. sorry.


> > telltale TSR hanging around?
> 
> What telltale TSR?  A program that can read and write directly to disk?
> If I am not mistaken, such programs are common enough not to be
> evidence of anything.  Having PGP on you is another matter, however.

I'd say having a TSR "hideit.com" loaded into high memory (installed size:
xxxx bytes) watching INT (whatever) would be a pretty good clues that
someone trying to determine that you were using a program to protect areas
of your disk would look for. Perhaps you could try and hide this, too; in 
any case, you address TSRs later...

> > > Simple.  You would take note of the starting address of the file.  And, 
> > > the length of the file.
> > 
> > how do you control individual writes? 
> 
> With a standard direct disk read/write utility.

uh, I don't have one. Do you?

I'm NOT talking about how to recover areas of your disk (you could use 
something like Norton Utilities to pull the noise file off the disk). 
What I'm trying to understand is how you plan to keep that area of your 
disk off limits. 

Like it or not, programs and OSs (if you can call Windows an OS) write to 
disk. Lots. Everywhere. How do you keep it from fragmenting the disk 
immediately and overwriting the space (whose address you have written 
down on that sheet of paper next to your computer?)

Try running windows with a temp swapfile. Run photoshop for windows (it 
writes its' own tempfile on the drive). Save a file from Word for Windows 
and try and control where it goes.


I'm not saying these problems can't be solved; I _am_ saying that what 
has been proposed thus far doesn't adequately address this (if you're 
looking at this as a genuine way to hide your data).


> > vs. where your data is kept. Authorize each write by hand? (PROGMAN.EXE 
> > is attempting to write to cylinder 12, track 14. Authorize (y/N)? ) 
> 
> Disable authorization.  Most DOSs allow direct writes without 
> authorization anyway.

No, no. We _need_ to protect the noise area. 

how? change the FAT? TSR? My example above was an attempt to try and
understand what a TSR you might build would have to ask, every single time
a regular write to disk was performed. (to protect your deleted noise
file).


> You need _not_ have a TSR with the location.  If you keep track of the 
> address/length yourself, the problem is eliminated.  The whole

except for the fact that your computer will overwrite your data (which, 
in fact, is *deleted* space, waiting to be written over) in the meantime.

> be a more elegant solution.  Otherwise, store your "noise" files 
> sequentially, on a floppy that you use only for storing encrypted data.  

Ah, a floppy? this makes 10 times more sense. With a floppy you wouldn't 
have haphazard writes to disk (as you do with your harddrive). 


> > Analysis: It seems with the systems I can think of you need to have the
> > area the noise file stored in either 1) standard (ick) or 2) kept in
> > memory so you don't overwrite it. If you don't protect it, I wouldn't
> > expect your noise file to have a very large half-life. :l Keeping the area
> > in memory (under protection) defeats the system. 
> > 
> 
> I'm sorry, this paragraph just went over my head.  Could you restate it 
> in another way, so I can attempt to comment?

sure. two choices:

1) We must protect our noise data.
	Keep it in a location on disk, keep a TSR in memory to protect
that area from writes. 

2) We don't protect our noise data. 
	Keep our data in a location on disk, keep the spots on paper, and 
hope that by the time we need to retreive it, the data hasn't been 
written over. 

I sure wouldn't want to count on 2), and it seems as if 1) defeats the 
purpose.


> > Aside: By the way, isn't the "noise" in your noise file is going to be
> > more random looking than other deleted areas of your disk? PGP compresses
> > and then encrypts; I'll bet that it is possible to distinguish pgp's
> > output bit frequencies from those of a binary or text file, which is what
> > the rest of the wiped space would most likely be. 
> > 
...

>  1 split the "noise" file into smaller parts which would be interspersed 
>    randomly among the other deleted grabage.  This would make for a less 
>    conspicuous disk; as, there are, normally, truely random sections of 
>    the disk along with the not-so-random sections.  Your bits of noise-file
>    will fit right in!

not bad. One thing to consider: we've moved all of our data to the end of 
the disk, anyway; we'd still have most of our important data at the end 
of the disk, which still might look conspicuous statistically.

>  2 use a steganorgraphy utility to embed the "noise" file in a section
>    of the other not-so-random garbage (as some people currently use those
>    same utilities to embed their PGP files in GIFs), and then delete it.
>    (Owning a stegonagraphy utility would, of course, be as conspicuous
>     as owning PGP.  So the same precautions would have to be applied.)

not bad. Takes (8 times?) more space, but should work.


Do you understand my objection to keeping track of the files' location by 
hand? It isn't that keeping track of the location/length of the file is 
hard, or retreiving it is tough; the problem is keeping the OS, etc from 
overwriting it in the meantime. 


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