From: "Trei, Peter" <ptrei@securitydynamics.com>
Date: Mon, 2 Nov 1998 23:37:09 +0800
To: "'Lucky Green'" <bill.stewart@pobox.com>
Subject: RE: TEMPEST laptops
Message-ID: <D104150098E6D111B7830000F8D90AE82406B7@exna02.securitydynamics.com>
MIME-Version: 1.0
Content-Type: text/plain





> -----Original Message-----
> From:	Lucky Green [SMTP:shamrock@cypherpunks.to]
> Sent:	Sunday, November 01, 1998 8:33 PM
> To:	Bill Stewart
> Cc:	cypherpunks@cyberpass.net
> Subject:	Re: TEMPEST laptops
> 
> On Sun, 1 Nov 1998, Bill Stewart wrote:
> [...]
> > Just using a regular laptop isn't enough; I've seen laptops
> > transmit recognizable images to a television (though I was probably
> > using AC power rather than batteries, and may or may not have had
> > the display mode set to LCD-and-monitor.)
> 
> Thanks for touching on the popuar myth that laptops radiate less than
> CRT's. Many laptops in fact radiate more compromising emissions than
> CRT's. Ross Anderson does his van Eck demos to undergrads using a laptop,
> because it works so much better than CRT's.
> 
> -- Lucky Green <shamrock@cypherpunks.to> PGP v5 encrypted email preferred.
	  
	Nearly all laptops have a built-in video port, for connection
	to an external monitor. This is often poorly shielded (usually
	just a plastic plug). I'd be curious to know how much the
	radiation from this port could be attenuated by (1) a metal
	plug contacting the laptop's ground plane, and (2) removing
	all the video-port specific circuitry (major surgery for a
	laptop :-( ).


	Peter Trei