(None)

bmorris@netcom.com (Bob MorrisG) writes:

> I've heard rumors through the years that CIA/NSA/whoever can aim a
> parabolic antenna at your window, read the electronic pulses surrounding
> your computer, and thusly determine what you are typing.  Is there any
> truth to this?
     If this is a reference to the TEMPEST attack, yes, they can. From
what I hear, it's trivially easy for them to do, because they have The
Right Equipment. Rumor also suggests that that The Right Equipment isn't
so difficult to come by. I don't pretend to understand the intricacies of
TEMPEST, but I do know that the government requires all of their computers
(used at any level of security above none) to be TEMPEST shielded. This
tells us its a real concern.

     There are other ways to beat TEMPEST, like making it damn near
impossible to get close enough to the computer in question to get a
reading.

                                        --Jeff
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On Sun, 3 Jul 1994, Jeff Gostin wrote:

>      There are other ways to beat TEMPEST, like making it damn near
> impossible to get close enough to the computer in question to get a
> reading.

Or could it be possible to put out enough 'garbage' radiation to throw 
them off? it seems to me that if you knew which frequencies to use, you 
could blast out cryptographicly random white radio noise which would make 
it imposible to determine what was 'good stuff'. Basicly the concept is 
to encrypt all of your wasted radiation with a one-time pad, and throw 
away the keys.

Happy Hunting, -Chris.

______________________________________________________________________________
Christian Douglas Odhner     | "The NSA can have my secret key when they pry
cdodhner@indirect.com	     | it from my cold, dead, hands... But they shall
pgp 2.3 public key by finger | NEVER have the password it's encrypted with!"
cypherpunks         WOw            dCD           Traskcom          Team Stupid
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------------------------------------------------------------------------------

> 
> On Sun, 3 Jul 1994, Jeff Gostin wrote:
> 
> Or could it be possible to put out enough 'garbage' radiation to throw 
> them off? it seems to me that if you knew which frequencies to use, you 
> could blast out cryptographicly random white radio noise which would make 
> it imposible to determine what was 'good stuff'. Basicly the concept is 
> to encrypt all of your wasted radiation with a one-time pad, and throw 
> away the keys.

	Yes you can jam TEMPEST detection systems.   Since many of them
use correlation detection technology to extract weak repetitive signals
from uncorrellated hash, you had better radiate coherent garbage
rather than just lots of noise, since the processing gain of the coherence
can be rather large (tens of db or more).

						Dave Emery

And that is why they don't let you take radios anywhere near their
equipment either...

-NS