From: ichudov@Algebra.COM (Igor Chudov @ home)
Date: Thu, 24 Dec 1998 09:08:47 +0800
To: mmotyka@lsil.com
Subject: Re: Question about 'TEMPEST': UPS
In-Reply-To: <3681858B.4028@lsil.com>
Message-ID: <199812240040.SAA07841@manifold.algebra.com>
MIME-Version: 1.0
Content-Type: text



Michael Motyka wrote:
> 
> 
> >
> Now... Just curious, if I simply make my study into a faraday cage via
> use of fine (< 1/2 inch) chicken wire, and insulate my power system from
> the computer emenations, would that be enough? Chicken wire is not that
> expensive, and I think that I could make it look nice on walls.
> >
> 
> The cages I've used were framed in wood and had several layers of copper
> screening. The mesh was like standard window screen, <.125". There were
> two, I think sometimes three, layers. The corners/joints were copper

Michael,

Was the amount of work involved really necessary? What do three layers
accomplish compared to just one?

> sheet. The screen was soldered to the corners. The doors were stepped or
> beveled and had several sets of fingers - indside edge, outside edge,
> perhaps one intermediate. Screen makes ventilation easier. Power should
> be brought in through a separate, partitioned, shielded box with
> filtering in each partition. Phone lines, same thing. You trust your
> apps, os and TCP/IP stack to not rat you out? If not, work off-line
> always.

Right.

> Al foil if it were thick enough would be OK but how do you reliably join
> edges? 

Glue? Perhaps some weak glue that would not destroy the underlying paint.

> Converting your study is non-trivial. The door would look like crap. You
> would need the euivalent of a door over the window.

My window has a mesh on it. Is that not enough?

> I wouldn't trust 1/2" galvanized chicken wire for containing anything
> but chickens or other non-gnawing furry woodland creatures.

Is that confirmed by evidence?

The reason for my question, I think that I somewhat value TEMPEST
protection, but not enough as to cover my whole room with expensive and
ugly looking copper or three layers of mesh and ferrite. I don't want
all of it to be too conspicious.

	- Igor.