-----[ So, you think you're secure? ]-----
                           by: Mr. Zippy!

INTRODUCTION:
   You've finally done it.  You compiled PGP yourself to make sure
   you're running a clean version, and you chose a passphrase that no
   one would ever guess.  You didn't write it down, so the FBI would
   never find it if they raided you.  You don't even encrypt messages
   while online, to prevent someone from monitoring the data line
   in hopes of trapping your passphrase.  In fact, you regularly
   wipe your swapfile so there's no traces of it anywhere.

   There's no way anyone will ever get your passphrase unless they
   beat it out of you, right?  WRONG!

   Remember that black van parked accross from your computer room's
   window?  They're not tapping your phone line or using a lazer mic
   to tape your conversations.  They're watching everything you type
   scroll accross a little monitor, and recording it all to VHS tape
   for later study.

   No, I didn't see this on the X-Files last week.  The technology to
   do this is available now (for as little as $200).  It's called
   van Eck radiation, and information about it has been classified
   by the Governments of the United States, England, and others.

HOW IT WORKS:
   Remember the interference on your TV when you fired up your Vic 20
   computer or printed to that old dot-matrix printer?  The
   interference was caused by electromagnetic radiation (known as
   van Eck radiation, after a researcher who published a paper on the
   subject).  In fact, you could often tune that Vic 20 computer in on
   an old black-and-white TV with fine tuning controls.  You didn't
   know it then, but you were using a van Eck device.

   The theory behind van Eck radiation is that all electronic devices
   emit some level of electromagnetic radiation.  This radiation can
   be detected by devices which are basically modified TV receivers.
   By tuning the receiver into the frequency your monitor is on, you 
   can watch everything scroll by.  Not only can your screen be
   monitored, but your printer, keyboard, or any other electronics
   device you may be operating.

WHAT IS AT RISK:
   Think about the kind of data you display on your computer monitor.
   Your financial records, personal letters, business proposals, or
   anything else you wouldn't want others to see can all be monitored
   and recorded for later review.  The information on your screen is
   the easiest to capture - you just need to tune the signal in on
   another screen.  It can be recorded on any standard VCR.
 
   Anything you type on your keyboard can also be monitored.  This
   includes your PGP key, the password for your 'net provider, or
   your credit card number.  So just because it's not displayed on
   the screen as you type it doesn't mean that it can't be captured by
   someone who really wants it.  Your printer and FAX machine are not
   immune to van Eck evesdropping, either.  

   Capturing the van Eck radiations from a keyboard, printer, or FAX
   can be more difficult than those from a monitor.  It is necessary
   to have the exact same model available to analyze before you can 
   figure out what you have captured.  The concept is still fairly
   simple:
         If you use a "Brand A" keyboard, I'll buy the same
         model. I hit each key, and watch the pattern on a
         scope.  Now, I watch the patterns come out of your
         keyboard, and match them to those I've already
         figured out.  Suddenly, your secret password isn't
         much of a secret any more.

   The same is true of printers and FAX machines.  If you have the
   same model, you can figure out each signal in advance, and then
   reading the captured output becomes easy.

WHO IS AT RISK:
   Everyone.  You don't need to be a criminal trying to hide your
   activities from law enforcement officials to be concerned about
   van Eck eavesdropping.  Consider the value of the data on your
   screen - what it it worth to someone else?
   
   Here's an example of various situations and types of information
   that could be gained by monitoring van Eck radiation:

      - Bankers (account data, transaction passwords)
      - Brokers (data leading to insider trading)
      - Law Enforcement (information on current investigations)
      - Designers, Architechts (current plans, models)
      - Software Designers (new algorithms and techniques)
      - Unfaithful Partners (letters to the "other")

HOW TO PROTECT YOURSELF:
   Over the years, electronics devices have been designed to give off
   less and less interference.  For example, I can set my laptop on 
   top of my TV and not cause any noticable disturbance.  This means
   that long-range detection of van Eck radiation is not practical.

   Instead, the easier way is to plant transceivers that detect the
   radiation, and transmit it to monitoring posts farther away.
   Devices used to detect "bugs", radio scanners, and physical
   inspections of your equipment and surrounding areas can help to
   turn up transceivers of this type.

   It's a well known fact that if you're getting bad TV reception,
   you can attach the antenna to the cold water pipe and it improves
   drastically.  In the same way, electromagnetic radiation can be
   detected through building wiring or water pipes.  It would be
   nearly impossible to get your equipment away from water pipes or
   elecrtical wiring.  Therefore, you'll need a way to ensure that
   no radiation emits from your equipment.

   The NSA has created a specification for hardware which emits
   minimum ammounts of electromagnetic radiation (called "Tempest").
   Of course, if they were to publish this specification, they would
   not be able to eavesdrop on van Eck emmisions themselves.  The
   concept is obvious, though.  Equipment should be enclosed in
   cases which trap emmisions inside.  The electrical supply should
   either be isolated or be "dirtied" with dummy emissions.  The room
   itself should be shielded such that detection from outside is
   impossible.

SUMMARY:
   If you have somthing to hide, you need to be aware of all the ways
   it can be discovered.  Not everyone needs to build a safe room to
   ensure that their information stays private.  However, if the
   information on your screen is worth more to others than it is to
   you, you should take precautions to ensure it doesn't get out.

CREDITS: 
   Not much information is available on van Eck Radiation, due to
   the topic being classified by most Governments.  Most of this
   information was obtained from one of these three sources:

   "Information Warfare" by Winn Schwartau (excellent book)
   "Computers and Security" December, 1985 issue
   Anonymous computer monitor technician at local repair depot