anti-RF window film

Leichter, Jerry leichter_jerrold at
Wed Jun 27 12:24:34 EDT 2007

| A company is selling a window film that blocks most RF signals.  The
| obvious application is TEMPEST-shielding.  I'm skeptical that it will
| be very popular -- most sites won't want to give up Blackberry and
| cell phones...
Real life follows fiction?  There was a Law and Order episode a year or
two back in which a high-tech company used some alleged technology like
this - a fine mesh of wires over the windows.  (An important clue was
one of the detectives noticing that the mesh had been disturbed.
Someone had replaced the wires in a small region with black thread, then
hid a cell-phone repeater outside the window.  As I recall, the reason
for doing was just your typical hacker "you try to stop me, I'll get
around you" trick.)

There were also reports not that long ago of a paint that provided
RF shielding.  On a more refined basis, there was some kind of
material suitable for walls that had embedded antennas.  You cut
them for a particular frequency range, and they provided very good
shielding in that range.

There is clearly a demand for this kind of thing.  New technologies
are making a hash of the old (sometimes not so old!) rules.  Two

	- The day of open access to the Internet from businesses is long
		is long gone in most places.  All kinds of concerns feed
		into this; a big part is concern about liability when
		employees access "inappropriate" sites.  This will all
		seem a bit silly when the penetration of high-speed
		wireless Internet access reaches reasonable levels.

	- Insider trading rules have placed all kinds of interesting
		restrictions on how trading firms do business.  In
		particular, every phone message in and out of
		"sensitive" areas is recorded, as is all email.
		But cell phones, text messaging, and so on bypass
		all that.  I gather some firms are responding by
		requiring that employees use only company-provided
		cell phones.  (Whether those calls get recorded is
		another question.)  How well they'll be able to
		maintain such policies, as cell phones morph into
		multi-function personal devices, is an open question.

With all this going on, the desire to just finesse the whole problem
by physically blocking signals is certainly only going to grow.

Interesting times.
							-- Jerry

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