From: jkreznar@ininx.com (John E. Kreznar)
Date: Tue, 12 Oct 93 19:41:55 PDT
To: cypherpunks@toad.com
Subject: Spread-spectrum net (vulnerability of)
In-Reply-To: <Ugip0Ky00awQIzQl9m@andrew.cmu.edu>
Message-ID: <9310130241.AA06390@ininx>
MIME-Version: 1.0
Content-Type: text/plain


> Secondly, the
> transmitter doesn't necessarily have to be exposed, it could be kept
> hidden and only the antenna would need to be exposed.

Not even the antenna should be visible.  Remember, for spread spectrum radio
detectable only by the intended receivers (which use the correct spread-spectrum
code for coherent detection), the power density should be hardly distinguishable
from the ambient noise.  One way to arrange this is to put the antenna inside of
a physically secure perimeter, outside of which the power density is too low for
noncoherent detection.  The perimeter can be optically opaque (e.g. a building),
as long as it leaks enough r.f. in the direction of the receiver(s) for coherent
detection.  Preventing noncoherent detection may often require _attenuation_ of
an otherwise too-powerful signal, and the building may serve part of this
function.

> Plus the antenna would be easy to disguise or hide in many places.

Yup.

	John E. Kreznar		| Relations among people to be by
	jkreznar@ininx.com	| mutual consent, or not at all.