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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."
This post is not insightful!
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 for more info.
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.
The article does not explain at all what quantum cryptograpy is and how it's different from the cryptograpy we all know. Ah, but here's wikipedia to the rescue http://en.wikipedia.org/wiki/Quantum_encryption:
Quantum cryptography uses quantum mechanics for secure communications. Unlike traditional cryptography, which employs various mathematical techniques to restrict eavesdroppers from learning the contents of encrypted messages, quantum cryptography is based on the physics of information. Eavesdropping can be viewed as measurements on a physical object -- in this case the carrier of the information. Using quantum phenomena such as quantum superpositions or quantum entanglement one can design and implement a communication system which can always detect eavesdropping. This is because measurements on the quantum carrier of information disturbs it and therefore leaves traces.
assignment != equality != identity