At 7:56 PM -0800 12/22/98, Tiny wrote:

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I`m sorry to ask such a stupid question. Is 'TEMPEST' an acronym, and if so, what exactly does it represent?

It was not originated as an acronym, though some have labored to find the words to make it one, sort of. Best to treat it as not being an acronym. It's a set of specs and testing methods for measuring and controlling RF emissions by computers and other electronic equipment. Shielding with metal enclosures, with filters on inputs and outputs, and so on. The full TEMPEST specs are more or less classified, as might be expected. (Because one does not lightly tell one's enemies what one is measuring for.) Contrary to popular rumor, it is not "illegal" to shield computers, to "use TEMPEST methods," as it were. --Tim May We would go to their homes, and we'd kill their wives and their children. We would kill their families ---------:---------:---------:---------:---------:---------:---------:---- Timothy C. May | Crypto Anarchy: encryption, digital money, ComSec 3DES: 831-728-0152 | anonymous networks, digital pseudonyms, zero W.A.S.T.E.: Corralitos, CA | knowledge, reputations, information markets, Licensed Ontologist | black markets, collapse of governments.

Just curious, if a computer is connected to the electric power through a UPS, does that reduce emissions leaked into the electrical system?:wq

Bill Stewart wrote:

At 09:39 AM 12/23/98 -0600, Igor Chudov @ home wrote:

...

Just curious, if a computer is connected to the electric power through a UPS, does that reduce emissions leaked into the electrical system?:wq

It should probably reduce them a bit, depending on your UPS design, but if you have to worry about people monitoring your electricity for contraband bits, you've got a whole raft of other things you'd better start taking care of, like disk encryption and

Very true. I thought about this too. The question that I ask is, how much $$ am I worth to whoever might want to snoop at me? And then I spend money/time (my time is freely convertible to money) accordingly.

offsite backups and signs on the door indicating that you will or will not shoot at police if they do or do not have warrants....

Well, I personally hate these signs, they are very unfriendly.

The converse is that if you've got an electrical filtering system as part of your TEMPEST protection, whether it's in your computer's power supply or separate or both, you tend to have really nice clean power feeding your computer, which is a Good Thing.

Hmmm, nice point. Now... Just curious, if I simply make my study into a faraday cage via use of fine (< 1/2 inch) chicken wire, and insulate my power system from the computer emenations, would that be enough? Chicken wire is not that expensive, and I think that I could make it look nice on walls. igor

Thanks! Bill Bill Stewart, bill.stewart@pobox.com PGP Fingerprint D454 E202 CBC8 40BF 3C85 B884 0ABE 4639

- Igor.

At 05:21 PM 12/23/98 -0500, Frederick Burroughs wrote:

Igor Chudov @ home wrote:

...

Now... Just curious, if I simply make my study into a faraday cage via use of fine (< 1/2 inch) chicken wire, and insulate my power system from the computer emenations, would that be enough? Chicken wire is not that expensive, and I think that I could make it look nice on walls.

How effective is aluminum foil (crinkled and layered)? It's cheap, easy to install and remove, and in concert with some halogen lighting, be host to any number of suspicious activities.

Neither one will make a dent from a Tempest perspective, though the foil might disperse heat enough to protect your dope farm :-) Bettter to build an RF-tight box for your PC and use fiber cables, and you'll still need to do really special power filtering. The Army used to use copper screen cages for computers back in the 70s, which got about 60dB worth of shielding. When I ran a TEMPEST-shielded room in the mid-80s, the specs said (roughly) that you needed 100dB of shielding for a room with computers in it, and the room technology we used gave about 110-120dB depending on how tight our door gaskets were. It used particle board with sheet metal on both sides and special edge/corner joints, and you packed copper-wool into any loose area and copper tape on any flat areas that had leaks. At the time you needed to be very careful about joints between anything, because RF just _leaks_, and we watched frequencies up to about 450MHz, since then-current computer equipment didn't have harmonics at anything like that high a frequency - but it still didn't take much of a leak to peg the meters, in spite of that being a .6 meter wavelength. Well, 1.5MIPS Vaxen are a bit out of date now, 300MHz Pentiums are common, and they've got all sorts of harmonics out there. If you want a penetration in the walls, e.g. for air or fiber optic cables, you needed some ratio I've forgotten between the depth and width of the hole; A two-inch deep hole could be about 1/4" across -- your 1/2" flat chickenwire would be pretty transparent. There's newer stuff now - some kind of carbon-fiber cloth with aluminum in it that's really nice to wallpaper with, but you still need to handle all the joints, which is tough to do. Other than protecting your dope farm, tin foil's not real useful, though I suppose you could line your hat with it to keep microwaves out :-) What's scary is that I _have_ seen a catalog (mostly NewAgey health scams) that sold RF-shielded hats; I forget if they were metal-lined or carbon-fiber. Thanks! Bill Bill Stewart, bill.stewart@pobox.com PGP Fingerprint D454 E202 CBC8 40BF 3C85 B884 0ABE 4639