From: norm@netcom.com (Norman Hardy)
Date: Fri, 14 Jun 1996 11:32:33 +0800
To: cypherpunks@toad.com
Subject: Class III InfoWar: TST Article
Message-ID: <ade632bf01021004d335@DialupEudora>
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There are two things that they may be speaking of:
1. Causing transient errors to crash the system and cause restarts that may
take many minutes.
2. Actually damage the machines.

I imagine that only a small fraction of the energy required to damage the
hardware is necessary to introduce serious transient errors. IBM used to
test the main frames as they installed them. They had to resist several
inch sparks drawn between the machine and a one meter frame. Software
diagnostics ran during the test. I think that few desk top machines would
survive that.

EMP (Electro Magnetic Impulse), a side effect of nuclear devices, is
purportedly able to damage electronics over distances of many miles. Some
weapons may be designed to enhance this.

Ordinary high explosives can produce a scaled down result. EMP is strategic
only because it  damages electronics that are too far enough to be damaged
by the blast. I suspect that high explosive EMPs are similar in this
regard.

The physics behind this is not abstruse. A significant part of the
explosive energy can be turned into EMP whether the source is nuclear or
chemical. How well it can be directed is probably highly classified. The
"antenna" is vaporized in either case and dissipates much of the energy.
The energy comes out in 10's of microseconds for high explosives and
fractions of a microsecond for nuclear. I don't know how much it takes to
fry an IC but judging from the wrist straps that are recommended for
installing ICs I would guess that it is a fraction of a Joule. (I once
discovered that a one Joule jolt really hurt.)

Faraday cages attenuate EMP by the same factor that they attenuate secrets.
I think that if a blast doesn't damage the cage then neither will the EMP.
Of course the cage may survive but fail to protect the interior
(insufficient attenuation). I don't know whether a cage sufficient for
tempest is sufficient for EMP protection. Comm lines and power cables go
thru the cage and cause problems here as well. Perhaps hefty surge
protectors suffice here. Communications equipment outside the cage should
at least be equipped to recover quickly upon transient error and not tear
donw circuits. Normal error control can then hopefully compensate for the
transient.  (IP, ATM, Frame relay??)

A large capacitor can discharge a lot of power in a short time without
causing nearly so much commotion as an explosion. Discharging a one kg
25000 volt capacitor makes a lot of noise, however. I don't know how well
it can be muffled.