-----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