At 02:08 PM 5/28/96 -0500, Andrew Loewenstern <andrew_loewenstern@il.us.swissbank.com> wrote:

Bill Stewart writes:

...

Also, of course, your electrical power system needs to be shielded and filtered, so only 60Hz gets through, unless you plan to stick to laptops and bring in spare battery packs. At HoHoCon a few years ago, someone did a tempest demo and mentioned that signals could be recovered from water pipes! Fire sprinkler systems were specifically mentioned...

Yup. When you're installing a shielded room with waterpipes, it's best to use a chunk of plastic pipe just outside the shieldwall, and you need to make sure the plumbers use teflon tape instead of pipe dope ( unless it was the other way around; it's been a while.)

Theres a lot of different avenues for your eminations to be recovered, some you may not have thought of. Like crypto, tempest is economics.

And like crypto, there are lots of diddly little things you've got to check to make sure you've done _all_ of them correctly. Unlike crypto, however, it's generally easy to find out if you've made a mistake; big mistakes peg your test meter, little ones require you to wave the meter around everywhere and watch for little motions. Also unlike crypto, little mistakes generally won't lose the whole game for you; if somebody's got to watch for six months to accumulate enough leaked electrons to find out the Secret Plans, and you haven't noticed the black van with all the antennas parked out in your parking lot by then, you've got far more serious troubles than just a few stray electrons :-) You may also notice that you can't park your black antenna-van too near the Pentagon. It's not just because they think you're hauling fertilizer; electromagnetic emanations follow this nice square-law that means that a few hundred meters of extra distance makes it _much_ harder to detect the signal you're looking for, as well as mushing it together with all the other stray signals from the building. # Thanks; Bill # Bill Stewart, stewarts@ix.netcom.com, +1-415-442-2215 # goodtimes signature virus innoculation