1996-12-05 - Re: Laptops and TEMPEST

Header Data

From: Joel McNamara <joelm@eskimo.com>
To: stewarts@ix.netcom.com
Message Hash: 2008278c0a767a16deac450e78aa3b3038110c4cd0d1b51db7d1a2b2e33a6fa9
Message ID: <>
Reply To: N/A
UTC Datetime: 1996-12-05 22:19:50 UTC
Raw Date: Thu, 5 Dec 1996 14:19:50 -0800 (PST)

Raw message

From: Joel McNamara <joelm@eskimo.com>
Date: Thu, 5 Dec 1996 14:19:50 -0800 (PST)
To: stewarts@ix.netcom.com
Subject: Re: Laptops and TEMPEST
Message-ID: <>
MIME-Version: 1.0
Content-Type: text/plain

Thinking that LCD screens reduce the risks of emanation monitoring is a
dangerous misconception (at least under a high threat model).  LCDs'
current requirements are pretty small, and they only emanate a low magentic
and electrical field.  However, the gotcha with current laptops is their
backlighting.  Electric and magnetic fields are considerably higher
compared with a low-res/contrast device.

There are documents that circulate within certain security circles that
list just how noisy (and therefore easy to monitor) various off-the-shelf
machines are.  It would be an interesting project for some ham radio type
Cypherpunks to measure their machines, and publish the results.  Or, for
some well connected person just to scan and anonymously post such a
document to the list.  Of course, I'd never encourage anyone to do
something illegal.