From scotartt <>
Date Thu, 28 Oct 1999 10:37:27 +1000 (EST)
In-reply-to <> from "Rask" at Oct 28, 99 01:18:56 am

[: hacktivism :]

> well, since a monitor display is a matter of lines created successively, I
> don't think it should be hard to reconstruct an image, if you can pick up
> the subtle differences in the amount of radiation set free at any given
> point in time... and if you know the screen's frequency.
> According to Wired (if I remember correctly), exactly this has already been
> done.

Yes, I understand how it works, but to do that would involve tuning into a
very select band of frequencies. your screen information probably will NOT
be decodable at just ANY frequency (i.e. X-Rays). In fact just exactly
WHAT  frequency was one of the bits of information the NSA deemed of
'national security interest' and refused to release under FOI.

X-Rays would be given off so --intermittently-- to be useless. X-Ray
emissions would probably be a great generator of true RANDOMNESS for
crypto systems. Also, they would have to be very low POWER (otherwise
monitors would be illegal on health grounds!), which means a piece of
PAPER will stop them.

> Also, the idea just struck me that tempest could possibly play a valuable
> role in collecting specifications for new enemy equipment and such... but
> that's just an idea, and it's late and I need sleep.

Awww really, you think? ;)

That's what SIGINT was even BEFORE they learnt to crack ENIGMA. 

That's why I signed a document saying I'm in breach of the OFFICIAL
SECRETS ACT threatening all sorts of dire nastiness if I ever so much as
breathe MENTION of the frequencies, radio profile and other information of
the ECM/ECCM and SAM systems I worked on (which, convieniently, 15 years
later, the classified details of which I forget anyway).


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