WAS: Thermal Imaging Decision Applicable to TEMPEST?

[David G. Koontz]

Is the average person susceptible to TEMPEST attacks?

"Arnold G. Reinhold" wrote:
> 
> TEMPEST is not shut down by any means. This decision applies to homes
> and places where there is an reasonable expectation of privacy (like
> a phone booth). The status of computers in offices, cars, and public
> places is less clear. Your data stored on someone else's computer
> outside you home is apparently not protected (they got Kyllo's
> electric bills legally without a warrant). In any event, the NSA can
> still use TEMPEST against foreign nationals and overseas, the FBI can
> use it against US nationals with a warrant, and the government can,
> de facto, use it secretly, as many people believe they now use
> wiretapping, to develop information that leads to other evidence that
> is admissible.
> 

TEMPEST is the control of compromising emanations - the prevention of
secrets leaking out.  Contrast this with FCC or EN regulations for
EMI and difference is separating secret from not secret information -
RED BLACK separation.  Not having looked at any of the NACS*M documents
on John Youngs site, and not having seen them for almost 30 years
otherwise, one emphasis you see is on frequency content of emissions.
The FCC specs  start at a frequency where you could interfere with
CB radios.  Changes in the last decade or so, driven by the Europeans
to eliminate such things as power factor flicker on lights caused by
the motor in your laser printer have greatly added to how well protected
the equipment is that we buy today.

The major concerns are low frequency stuff, meeting EMI integrity in
installation (actually using properly shielded cables and the like),
and maintaining RED BLACK separation.  One could hypothesis that so
much of TEMPEST has been declassified because it is essentially covered
by FCC and EN regulations.  If you look at modern military grade crypto gear
designed for office use, it appears to be similar in design to COTS
electronics.
Looking through some of the more recent Air Force manuals on John Youngs
site you see an emphasis on controlling accidental emissions - decoupled
phones when on hook, no transmitters or devices that could generate RF
in secure facilities and the like.  There is a specification on his site
that originates from the CIA (which controls security compartmentalized
information), that essentially relaxes physical EMI protections.  You can
build a SCIF without copper mesh in the walls today.  An important element
is physical separation (distance) between any attacker and equipment
that can radiate (at mandated reduced levels).

Thats not to say that the average computer user can't run up against 
(knowingly or unknowing) a problem they can't cure.  How would the average
guy deal with coupling between an ethernet cable and a phone line?  Guess
what, if you adhere to what you read in the manuals you can be more likely
to be immune from monitoring than not -  the difference is that unless
you do it, no one is going to do an RF sweep of your home or office.

(I recall a getting a trouble call while in the Air Force from a civilian
contractor at a classified location.  Seems their Gold phone (a secure
phone system with link encryption to a small central switch) was receiving
radio station AM 610 when ever the handset was offhook.  Something very
embarassing to say the least for a phone intended for SCI.  Turns out there
was a ground loop on an audio cable to the phone set, and a cold solder
joint acting as a rectifier - an accidental crystal radio.  We cured this
by rote examination of the installation against guidelines (at least to
find the ground loop).  Several years later I happened accross the same
phenonenom in a video game while working for a video arcade game company 
 - same radio station, too.)

Today I design digital equipment that operates in the gigahertz and up 
range - as will most computers in the next year or two.  There is an
additional
barrier to monitoring digital microwave rate signals.  The equipment is
terribly
expensive, and out of budgetary range of all but private corporations and
national governments.


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