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Quantum Cryptography
MagiQ Technologies is now selling an actual product that uses single photons to exchange keys over fiber optic lines. Navajo systems use photons to transmit encryption keys over fiber-optic lines, and the security is based on the quantum law that an observer--an eavesdropper in this case--perturbs the system by observing it.
This isn't new. The basic science was developed in the early 1980s, and there have been steady advances in engineering since then. I describe how it all works--basically--in Applied Cryptography, 2nd Edition (pages 554-557).
I don't have any hope for this sort of product. I don't have any hope for the commercialization of quantum cryptography in general; I don't believe it solves any security problem that needs solving. I don't believe that it's worth paying for, and I can't imagine anyone but a few technophiles buying and deploying it.
It's not that quantum cryptography might be insecure; it's that we don't need cryptography to be any more secure.
Security is a chain; it's as strong as the weakest link. Mathematical cryptography, as bad as it sometimes is, is the strongest link in most security chains. The computer security, the network security, the people security--these are all much worse.
Cryptography is the one area of security that we can get right. We know how to make that link strong. Maybe quantum cryptography can make that link stronger, but why would anyone bother? There are far more serious security problems to worry about, and it makes much more sense to spend money securing those.
It's like defending yourself against an approaching attacker by putting a huge stake in the ground. It's useless to argue about whether the stake should be fifty feet tall or a hundred feet tall, because the attacker is going to go around it. Even quantum cryptography doesn't "solve" all of cryptography: the keys are exchanged with photons, but a conventional mathematical algorithm takes over for the actual encryption.
I'm always in favor of security research, and I have enjoyed following the developments in quantum cryptography. But as a product, it has no future.
It's always the people that are the problem and they still have to be at either end using the system.