* To: cypherpunks@toad.com
     * Subject: My only words on "Electromagnetic Pulse" Damage
     * From: tcmay@sensemedia.net (Timothy C. May)
     * Date: Wed, 12 Jul 1995 10:22:45 -0700
     * Sender: owner-cypherpunks@toad.com
     _________________________________________________________________


Much discussion this morning about EMP, electromagnetic pulse weapons, HERF
guns, Winn Schwartau's "Information Warfare" scenarios, TEMPEST, etc.

Not closely related to Cypherpunks themes, but lots of speculation is
continuing. I happen to know a fair amount about chip vulnerability to
various kinds of radiation and electrostatic discharge, and have had
contacts with folks who know Schwartau. (I was also interviewed for a
Schwartau-oriented BBC television program called "The I-Bomb.")

Here's what I know:

* EMP can of course zap devices. High electric field gradients can induce
voltage drops that blow inputs, burn out circuits, etc. Lots of mechanisms
for this, of course. Latch-up in CMOS circuits, field oxide overvoltage
breakdown, etc. There is an entire sub-industry devoted to electrostatic
discharge (ESD), with conferences, products, consulting services, etc.

* However, getting the voltages coupled into circuits is another matter.
Modern chips can usually handle static charge buildups that are in the tens
of thousands of volts range (input protection devices are on the input
pads). Static discharge should be avoided (wrist straps, etc.), but most
modern devices will survive the static discharges that folks can generate.

* The point? A _distant_ (tens of meters away) source of electromagnetic
fields will have a pretty hard time of creating field gradients able to
equal these 10,000 volt local fields caused routinely by static buildup.
(Electric fields are of course measured in terms of "volts per meter"...do
the math.)

* The traditional EMP work is well-covered in each year's "Nuclear and
Space Radiation Effects Conference," the Proceedings of which are included
in the December issue each year of "IEEE Transactions on Nuclear Science
and Space Radiation Effects." I advise anyone interested in this topic to
consult these sources. (I've been to a few of these conferences, beginning
in 1978.)

* Most of the traditional EMP work is oriented toward the detonation of
nukes in orbit, where the interaction of the photons from the bomb with
electrons in the upper atmosphere create an electromagnetic field of
millions of volts per meter, the so-called "electromagnetic pulse" that
blows circuits. (This effect was apparently first noticed, by U.S.
scientists at least, after a 1962 high altitude burst over Johnson Atoll in
the Pacific, with electric circuits as far away as Hawaii being blown.)

* Schwartau has not, to my knowledge, ever seen a direct demonstration of
the effects he is describing in his book. In fact, much of his "HERF gun"
stuff is admittedly speculative.

* He has gotten interest from British intelligence (MI-5 or MI-6, not sure
which) in his "scenarios" for knocking out financial centers with EMP bombs
and HERF guns. A friend of mine, who can speak up if he wishes here, has
had some contacts with Schwartau and may have started to do some
preliminary experiments on this stuff.

(The EMP/HERF folks in governments have of course a lot of experience here.
I'm just saying that the "Schwartau crowd" appears to just be getting
started on actual experiments, so any speculations in "Information Warfare"
should be taken as just that, as speculations.)

* As a matter of commenting on one thread about damage to the "HERF gun"
itself, the conventional notion is that such a device would be a "set and
forget" device, with a suitcase planted near a corporate office complex and
set to "detonate" some time later. All the talk about reuse and damage to
the operator is beside the point. (As is the speculation about effects on
the human  body....bodies can withstand incredibly high fields, so long as
a ground path for current does not form (electrocution)....I could go on
about this, but won't.)

* In my opinion, Schwartau's chief interest is in spreading fear and
concern about the "vulnerability" of the world's "information
infrastructure." This cranks up interest in his book, in getting talk show
interviews, etc. He may have "patriotic" motives as well, but I think a
large part of what we're seeing is the usual, and increasingly common,
journalistic hype.

This is not to say there is no basis for concern, just that this is not the
first and foremost concern. After, cutting power lines has long been an
easy way to knock out economic activity--it may have recently happened in
Penang, Malaysis, for example, where many chip assembly plans were knocked
off-line for a few weeks by a power cable cut.

This is all I'll say on the current debate on TEMPEST, HERF, EMP, etc.

--Tim May

..........................................................................
Timothy C. May         | Crypto Anarchy: encryption, digital money,
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