TEMPEST protection

Ladies and Gentlemen,

I would like to find out how hard (and expensive) would it be
to try to protect my computer by TEMPEST-like measures.

I am not an electrical engineer and am looking (hopefully) for
a relatively easy to understand do-it-yourself type of manual.

I have heard from my acquaintaince who is a tempest professional that 
it was not very possible. If that is indeed true, are there any
measures that can be taken to at least complicate spying on my computer?

Not that I think that Martians from the flying saucers are already
listening, but it is interesting to find out how to do this stuff.

Thank you very much.

	- Igor.

Russian spy Igor Chudov whispered:

>I would like to find out how hard (and expensive) would it be
>to try to protect my computer by TEMPEST-like measures.

>I am not an electrical engineer and am looking (hopefully) for
>a relatively easy to understand do-it-yourself type of manual.

  Having had electro-shock therapy, I consider myself 
somewhat of an expert in this area.
  I have an outdated computer which I set next to my new
computer, and I have self-running programs running on it
all the time. I also add a keyboard input device when I
want a little extra *noise* in the air. (It uses those 
*ducks* that swing up and down, dipping their beaks in
a glass of water.)

Not that I think that Martians from the flying saucers are already
listening, but it is interesting to find out how to do this stuff.

  For Martians, use an aluminum-foil hat. (That's common
knowlege).

TruthMonger

TruthMonger wrote:
>   Having had electro-shock therapy, I consider myself
> somewhat of an expert in this area.
>   I have an outdated computer which I set next to my new
> computer, and I have self-running programs running on it
> all the time. I also add a keyboard input device when I
> want a little extra *noise* in the air. (It uses those
> *ducks* that swing up and down, dipping their beaks in
> a glass of water.)

Actually, the computer you type on will be very easy to pick out
of the noise field with modest spy equipment sitting down the street.

There's a company (I lost the brochure) who sell EM attenuator
material, some preconfigured, and presumably some bulk.  It should
be easy to find on the Web.  Once you get some really dramatic
attenuation, particularly of the keyboard (and particularly during
password confirmations, etc.), you should do your own preliminary
monitoring with some of those band-sweep gadgets.  Steady noise
of course is nothing compared to the spikes from some of the keyboard
outputs...

Once you've identified all (we can hope, can't we) of the problem
signals still leaking through the shielding (albeit at greatly
reduced levels), you can direct different kinds of efforts there,
including random noise from other computers which use the exact
same output devices.

HP has been selling Tempest-approved PC's since the early 1980's
(if not before), and at not too steep a price, either, so it can't
be all that difficult, once you get a handle on it.

<sorry for the earlier finger glitch>

On Tue, 11 Mar 1997, Dale Thorn wrote:

> Actually, the computer you type on will be very easy to pick out
> of the noise field with modest spy equipment sitting down the street.
> 
> There's a company (I lost the brochure) who sell EM attenuator
> material, some preconfigured, and presumably some bulk.  It should
> be easy to find on the Web.  Once you get some really dramatic
> attenuation, particularly of the keyboard (and particularly during
> password confirmations, etc.), you should do your own preliminary
> monitoring with some of those band-sweep gadgets.  Steady noise
> of course is nothing compared to the spikes from some of the keyboard
> outputs...
> 
> Once you've identified all (we can hope, can't we) of the problem
> signals still leaking through the shielding (albeit at greatly
> reduced levels), you can direct different kinds of efforts there,
> including random noise from other computers which use the exact
> same output devices.

>From what I've seen, it's a lot easier for "the bad guys" to concentrate 
on monitor emissions - you can read the screen someone's looking at, and 
not just the key-clicks.  Won't get you blanked-out passwords, though.  
Much of the monitor's emissions may be out the back.

Other places to look for emissions: the power supply, and the connection 
points for peripherals.  Make sure you leave adequate ventilation, though 
(another tricky part).

Cynthia

===============================================================
		   Cynthia H. Brown, P.Eng.
E-mail:     cynthb@iosphere.net  | PGP Key:  See Home Page
Home Page:  http://www.iosphere.net/~cynthb/
Junk mail will be ignored in the order in which it is received.

        Klein bottle for rent; enquire within.

Cynthia H. Brown wrote:
> On Tue, 11 Mar 1997, Dale Thorn wrote:
> > Actually, the computer you type on will be very easy to pick out
> > of the noise field with modest spy equipment sitting down the street.

> Other places to look for emissions: the power supply, and the connection
> points for peripherals.  Make sure you leave adequate ventilation, though
> (another tricky part).

Funny thing was, first time I used PGP I was typing in a passphrase
and apparently PGP was doing something to the keyboard processor
on my laptop, because all of a sudden I thought I'd gotten bat's
ears - I could hear interesting new noises every time I pressed a
key, which I hadn't heard before (at least at an audible volume).

It occurred to me that typing in a PGP passphrase would be a
particularly bad time to increase the emissions....