Quantum cryptography gets "practical"

[Dave Howe]

Tyler Durden wrote:
> Oops. You're right. It's been a while. Both photons are not utilized, 
> but there's a Private channel and a public channel. As for MITM attacks, 
> however, it seems I was right more or less by accident, and the 
> collapsed ring configuration seen in many tightly packed metro areas 
> (where potential customers of Quantum Key Exchange reside) does indeed 
> make such attacks much easier.
> 
> Come to think of it, an intruder that were able to gain access to a CO 
> without having to notify the public (Patriot Act) should easily be able 
> to insert themselves into a QKE client's network and then do whatever 
> they want to (provided, of course, they have the means to crack the 
> 'regular' encryption scheme used to encode the bits--NSA).
> 
> Which means that, should a $75K/year NSA employee want to strike it 
> really, really rich, they'd be able to procure advanced notice of any 
> mergers/acquisition deals.
Unless someone has come up with a new wrinkle to this since I last 
looked, the QKE system indeed requires three channels - the key photon 
one which must be optical, and a conventional comms pair (the latter of 
course can be substituted with any comms pair you have handy, but if you 
are running fibre from A to B you might as well run three)
As all three require MiTM to be mounted, it would be better to have a 
physically diverse path for the conventional pair - but in a small city 
where you are patching the optical channel though the nearest exchange, 
this may not be practicable.
The "regular encryption scheme" (last I looked at a QKE product) was XOR....