Tyler Durden wrote:
An interesting thing to think about is the fact that in dense metro
areas, you pretty much have a "star" from the CO out to a premise (which
is the cause of deployment of "Collapsed SONET Rings"). This means the
other photon of your encrypted pair might easily pass through the same
CO somewhere, which would make the system suscpetible to a sort of man
in the middle attack. Or at least, your fancy quantum crypto system has
defaulted back to standard crypto in terms of its un-hackability.
Unless I am mistaken as to the Quantum Key Exchange process, only one
photon is ever transmitted, with a known orientation; the system doesn't
use entanglement AFAIK.
I note also that, as QKE is *extremely* vulnerable to MitM attacks, a
hybrid system (which need only be tactically secure, not strategically
secure) can be used to "lock out" a MitM attacker for long enough that
his presence can be detected, without having to resort to a classical
but unblockable out of band data stream. I think this is part of the
purpose behind the following paper:
http://eprint.iacr.org/2004/229.pdf
which I am currently trying to understand and failing miserably at *sigh*
Moral of this story is, even if this thing is useful, you'll probably
have a very hard time finding a place it can be deployed and still
retain its "advantages".
I have yet to see an advantage to QKE that even mildly justifies the
limitations and cost over anything more than a trivial link (two
buildings within easy walking distance, sending high volumes of
extremely sensitive material between them)
-TD
From: Dave Howe <[EMAIL PROTECTED]>
To: Email List: Cryptography <[EMAIL PROTECTED]>,
Email List: Cypherpunks <[EMAIL PROTECTED]>
Subject: Re: QC Hype Watch: Quantum cryptography gets practical
Date: Tue, 05 Oct 2004 17:48:30 +0100
R. A. Hettinga wrote:
Two factors have made this possible: the
vast stretches of optical fiber (lit and dark) laid in metropolitan
areas,
which very conveniently was laid from one of your customers to another
of your customers (not between telcos?) - or are they talking only
having to lay new links for the "last mile" and splicing in one of the
existing dark fibres (presumably ones without any repeaters on it)
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