First Quantum Cryptographic Data Network

jdubs writes to tell us ScienceDaily is reporting that scientists at Northwestern University and BBN Technologies have demonstrated the first truly quantum cryptographic data network. From the article: "Kumar's research team recently demonstrated a new way of encrypting data that relies on both traditional algorithms and on physical principles. This QDE method, called AlphaEta, makes use of the inherent and irreducible quantum noise in laser light to enhance the security of the system and makes eavesdropping much more difficult. Unlike most other physical encryption methods, AlphaEta maintains performance on par with traditional optical communications links and is compatible with standard fiber optical networks."

Will we know?

[SanityInAnarchy]

We know a working quantum computer, on a sufficient scale, can crack modern encryption in something like linear time, or at least better than the current exponential time. We know that no such computer exists now, or at least not on sufficient scale to enable the NSA to snoop all our encrypted traffic.

Or (tinfoil hat time) do we really? Will we know when this happens, or will it be classified and snapped up by the government? Would we notice that? (The way we did with the a-bomb -- contests were held for whose work could be classified the fastest.) Or would we only notice years later, when it's finally leaked...

Re:Quantum post

[waxigloo]

I agree. It would have been nice if the article compared what they have done here with what is already been done by commerical quantum key ditribution (www.magiqtech.com). It is not clear from the article what is actually the new breakthrough...

Re:Will we know?

[johndoe42]

Really? Last I heard, quantum computers were not known to be able to solve NP-hard problems in polynomial time, and, in the absence of cryptographic breakthroughs, breaking symmetric ciphers ought to be difficult NP problems. Grover's algorithm might help, but only enough to reduce the rate of exponential growth a bit (i.e. 256-bit encryption will stuff be effectively unbreakable by any technology, unless BQP >= NP).

That being said, quantum computers can easily break RSA, ElGamal, and related schemes (using Shor's algorithm, for example). But this quantum encryption thing, absent any details, doesn't look like it's trying to do assymetric encryption.

See http://en.wikipedia.org/wiki/Quantum_computing [wikipedia.org] for more info.

Re:Solution without a problem

[chicoryn]

I can't claim to be an expert on the subject but rather then an actual new encryption quantum cryptography is an way to ensure no one can listen without you knowing(Making use of the "Can't watch without changing" law in quantum physics), while it isn't that much of an problem right the computer power will continue increasing, better to have the solution before the problem right? And yes this isn't going to be an home device anytime soon since it's WAY to expensive for home use.

Re:Will we know?

[Anonymous Coward]

The problem is one of information theory - read Cryptonomicon for a good fictional overview of these type of issues - the problem is that *if* they had a working quantum decrypter could they use it yadda yadda, well, there's two options - either they start using it left right and centre and soon everyone *knows* that the NSA can read encrypted data (in which case the bright monkeys will switch back to one-time pads and the hell that is key exchange) - or the NSA will be very clever about it and only act on that information they have decrypted that they can explain coming from other sources, such as:-
1. crack PGP1024-bit message using quantum goodiness
2. get juicy intelligence from message
3. 'bust' someone in the 'organisation' who had access to this information
4. go public with/act upon the intelligence, claiming where needed 'x told us everything'

The whole issue is one the allies had to deal with throughout WWII since they had cracked enigma and so wanted to act on the intelligence without letting the axis know that we could read their codes.

Having said all that though - I'm a big believer in the cock-up Vs. conspiracy theory, meaning given two situtations it is usually always the case that the conspiracy is fantasy.