TEMPEST, Van Eyck Radiation, and Eavesdropping

[karn@qualcomm.com (Phil Karn)]

>surveillance.  In  the United  States it is  illegal for  an
>individual  to  take   effective  counter-measures   against
>TEMPEST surveillance.   This leads to the  conundrum that it

I really DO wish this particular bit of misinformation would go away!
It is most definitely NOT illegal to shield one's computers against
TEMPEST surveillance. In fact, the FCC requires that manufacturers
limit the same spurious radiations that TEMPEST exploits to minimize
interference to nearby radio and TV receivers. The details appear in
Part 15 of the FCC rules.  They are more stringent ("Class B") for
devices intended for home use, since receivers are much more likely to
be nearby than for devices intended solely for office use ("Class A").

The Part 15 interference rules for computers came into being in the
mid 1980s, so anything you may read about the ease of intercepting
computer emissions that was written before that time is somewhat
suspect.  Thanks to the rules, modern computers are FAR quieter than
those sold in the 1970s and early 1980s, though they're still not
completely silent.

Phil