Slashdot Mirror
BBN Announces Functional Quantum Encrypted Network
anzha writes "BBN Technologies has announced that under DARPA's Quantum Network Project to have built in conjunction with Harvard University the world's first functional quantum encrypted network. This is probably funded under DARPA's Quantum Information Science and Technology Program."
This scheme might be subject to denial-of-service attacks by eavesdroppers, but I'm sure they've thought of that in their network design. Probably they can send the keys via alternate routes in case of interruption of a link.
Have you read my blog lately?
Not all the laws, just P != NP.
None, except for one-time pads (which have other problems). For example, many schemes depend on the fact that it's impractical to factor large numbers. The truth is that nobody knows how to factor large numbers today, but it's also true that nobody knows how hard this problem really is. Perhaps someone clever will figure out how to do it tomorrow... and in the meanwhile, someone already has figured out how to factor large numbers using quantum computing. Nobody has built a quantum computer large enough to run the algorithm, but once they do, you can kiss all these schemes goodbye.
Am I part of the core demographic for Swedish Fish?
Yes, just like RSA, and Diffie-Hellman key exchange, SHA-1...
None of those are in patent. RSA was patented but that patent expired a few years back. SHA-1 was never patented nor was Diffie-Helman.
we don't have secure communications, what we have are communications that nobody knows how to break yet
Well, not exactly we have the One time pad but that aside: What makes physics different to mathematics? You can't prove a physical theory is true like you can a theorem. There is a small chance quantum mechanics is wrong and there is an alternate theory that describes the photons in a deterministic way.
Yes, it's a small chance.. but don't forget that there's also a small chance that you can find a quick algorithm to solve AES. Changing the laws of physics tends to happen once a century - Theorems on the other hand last forever.
Simon.
The point of quantum cryptography is not to make the crypto unbreakable, but to make attempts to eavesdrop on it detectable.
The network consists of fibre optic cables over which SINGLE PHOTONS are transmitted back and forth between "Alice" and "Bob". If anyone is trying to spy on you -- poof, your bits disappear, and you notice.
The actual crypto that's used on the network is fairly normal. The quantum part protects the key exchange.
Please try to get headlines right.
This is not quantum encryption. Photon entanglement simply allows the recipient to detect if someone was listening. It's much like a signature, only stronger (signatures only go bad if someone tries to modify the data; quantum state of entangled photons changes if anyone even looks at the data).
You don't want to send critical information over such a link. You use that link to send a symmetric encryption key. Then you use crypto.
Eve, a passive MITM (WITM), can prevent you from ever using crypto by keeping the link tapped. You keep sending crypto keys across, but each time you realize they've been compromised. You cannot get anywhere in that situation unless you use public key crypto, at which point the quantum-entangled nature of the link gets you no extra security.