In article ,
(TMartin831) wrote:

http://informationweek.com/story/sho...cleID=56200676

By Jim Nash Dec. 28, 2004

A small startup in Silicon Valley has an anti-intrusion tool that
sells for $69 a gallon--you supply the brush.

Force Field Wireless makes three products that it says can
dramatically reduce the leakage of wireless signals from a room or
building. The company's sales manager, Harold Wray, co-developed
DefendAir Radio Shield latex paint, which contains copper filings and
an aluminum compound. When spread evenly on a wall, the paint
reflects signals in frequencies from 100 MHz to 5 GHz. Paint four
walls, a floor, and a ceiling, and you effectively have a Faraday
cage, which is a specially constructed metal room that blocks all
radio signals in or out, suitable for a CIA director or a determined
shut-in.

Not a new idea.

Snip

DefendAir is nontoxic, contains no lead, and meets all U.S.
Environmental Protection Agency standards, Wray says. Besides the
paint, Force Field sells 32 ounces of a copper/aluminum powder that
homeowners can add to their own paint for $34. The company also makes
a window film that cuts down on signal leakage: A 30-inch-by-25-foot
roll is priced at $45.

None of this is new.

Copper is toxic in power form. The paint will be toxic in the
environment.


"This wouldn't be the first thing I'd do to secure a network," says
Spire Security's Lindstrom. "But in a crowded environment, in an
office complex, it might be a thing to do." It's better to implement
a solid authentication/encryption system, he says.

Snip

This is a waste of time. You don't have a Faraday cage unless all
walls, floor and ceiling are shielded and you can't have gaps in the
shield.

Even worse than the gap problem is that signals can be carried in and
out of a shielded area through any conducting wire that penetrates the
cage through common mode coupling.

Shielded rooms need filtering on all conductors in and out of the room.
If this is not done you don't have a shielded room that either keeps
signals out or in.

--
Telamon
Ventura, California