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First Secure Quantum Crypto Network Up and Running

Posted by timothy on Fri Oct 10, 2008 06:47 AM
from the all-new-perfect-forever-place-your-bets dept.
Encryption Security Communications IT Technology
John Lam was one of many readers to send in news that on Thursday, "at a conference in Vienna, Austria, as reported by the BBC, a European Community science working group built a quantum backbone using 200-km of standard commercial optical fiber running among seven sites and successfully demonstrated the first secure quantum cryptographic key distribution network. In addition, each of the seven links used a different kind of quantum encryption, demonstrating interoperability between the technologies. To paraphrase, the project focused on the trusted repeater paradigm and developed an architecture allowing seamless integration of heterogeneous quantum-key distribution-link devices in a unified framework. Network node-modules managing all classical communication tasks provide the underlying quantum devices with authentic classical channels. The node-module architecture uses a layered model to provision network-wide, end-to-end, provably secure key distribution."
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First Secure Quantum Crypto Network Up and Running 50 Comments More /

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  • from TFA "Albert Einstein, who discovered the quantum properties of photons of light - indeed, discovered the very concept of the photon - always resisted quantum theory's spooky behaviour, "God does not play dice", being among his oft-quoted objections.
    But experiments eventually proved that he apparently does, and also laid the technical foundations for today's quantum information revolution - cryptography, teleportation, and computation."

    Teleportation? Did I miss something here? Has matter been teleported

    • Teleportation? Did I miss something here? Has matter been teleported or is this just speculation?

      Yes. But it's only Photons that have been 'tele-ported' at the speed of light even.

      • Re: (Score:3, Interesting)

        by IceCreamGuy (904648)

        it's only Photons that have been 'tele-ported'

        It is actually not a particle like a photon, but only information that is teleported. Just in case your next question is "doesn't this mean we can communicate at the speed of light?" you must have a classical information channel as well in order to make sense of the teleported information.

        • "doesn't this mean we can communicate at the speed of light?"

          Actually, it has been possible to communicate at the speed of light for some time using, er, light by (eg) sending up smoke signals or waving. I think you meant "faster than light"...

          • Good points, I guess that is what I meant.

          • Actually, it has been possible to communicate at the speed of light for some time using, er, light by (eg) sending up smoke signals or waving. I think you meant "faster than light"...

            Cough... radio waves... cough

    • Re:Teleportation? (Score:5, Funny)

      by Zerth (26112) on Friday October 10 2008, @07:22AM (#25326343) Homepage

      xkcd is almost always relevant [xkcd.com]

    • But experiments eventually proved that he apparently does

      This is the part I find interesting - "apparently." We still do not fully understand, like when we inherit someone else's spaghetti code and, modify some method and say, "yeah, looks like that fixed the problem." Only, we aren't 100% sure, and then we find out it didn't fix it or it caused another issue, and ultimately we realize it's time to rewrite the whole damn thing.

      So the question is, how far will quantum [insert favorite flavor] go before we re

      • I think we'll discover that the universe really is a mess of hacks and spaghetti code, personally.

        By that time we'll be Greg Egan cyberheroes and we'll rewrite the universe as a universal turing machine, and live as strings of code in the quantum foam.

    • Teleportation? Did I miss something here? Has matter been teleported or is this just speculation?

      Its about a trick that lets you transfer the "quantum state" of one particle to another particle (at a distance) without "measuring" it and therefore changing it.

      If you want it in Star Trek terms, they haven't invented the transporter, but they have eliminated the need for the fictitious "Heisenberg compensator" which (as any Star Fleet cadet knows) allow the transporter to measure the exact state of every atom in your body without completely scrambling them in accordance with the uncertainty principle.

      Do

      • I don't think quantum encryption uses teleportation or entanglement, just the Uncertainty Principle. The photons (in a quantum state) are actually physically transferred through fiber-optics.

    • The wiki article posted earlier will give you more information, but let me tell you the depressing upshot.

      Nothing is really being teleported. Nothing can be transported faster than the speed of light using quantum teleportation. Not even information. Especially not information.

      There is a quantum interaction between two particles that happens instantly, but the particles themselves, and all the information contained in those particles, was transfered at sub-light speed when you separated them.

      It's still u

  • Better than ssl (Score:5, Funny)

    by sakdoctor (1087155) on Friday October 10 2008, @07:04AM (#25326255)

    You'll be able to tell if your web traffic has been snooped by the authorities because all your lolcats will arrive dead!

  • If I recall correctly, not the first (Score:5, Informative)

    by fwice (841569) on Friday October 10 2008, @07:05AM (#25326257)
    Under DARPA sponsorship, and together with our academic colleagues Harvard University and Boston University, BBN Technologies has recently built and begun to operate the world's first Quantum Key Distribution (QKD) network. The DARPA Quantum Network employs 24x7 quantum cryptography to provide unprecedented levels of security for standard Internet traffic flows such as web-browsing, e-commerce, and streaming video.

    The DARPA Quantum Network became fully operational on October 23, 2003 in BBN's laboratories, and has run continuously since.

    source: http://bbn.com/technology/information_security/quantum_cryptography [bbn.com]
  • "...seamless integration of heterogeneous quantum-key distribution-link devices in a unified framework."

    My buzzword alarm just core dumped.

  • Secure Key exchange. (Score:3, Interesting)

    by locofungus (179280) on Friday October 10 2008, @07:44AM (#25326521)

    I heard something about this on the radio last night (wasn't paying full attention).

    But they were talking about quantum key exchange. Assuming that they're then using a standard symmetric key to encrypt the link it's still theoretically breakable, just the key exchange that isn't.

    If they're quantum encrypting all the data then that's pretty astonishing - they were talking about video-conferencing so they need a reasonable bit rate and the fidelity rate has to be above 5/6[1] otherwise the link might be vulnerable to a quantum cloning attack.

    [1] Assuming the best attack is a universal quantum cloning machine. The maximum theoretical fidelity isn't known for most non-universal quantum cloning machines (but is trivially known for some - e.g. 3/4 for a naive measure and retransmit). I don't know whether it's possible to prove that the 5/6 is a sufficient lower bound on the fidelity.

    Tim.

    • Re: (Score:2, Interesting)

      by Bengie (1121981)
      "[...]Assuming that they're then using a standard symmetric key to encrypt the link it's still theoretically breakable[...]" depends on what you mean by "theoretically". According to my cousins professor in his Computer Science Encrption course, if you had a *perfect* 256bit symmetric key encryption, if you counted just bit flips and no other inefficiency of the system, on average it would take more energy to break the key than there is usable energy in the known universe. and from what I've read about q

      • Re: (Score:3, Informative)

        by locofungus (179280)

        Hmmm, not sure I agree with that assessment.

        if you had a *perfect* 256bit symmetric key encryption, if you counted just bit flips and no other inefficiency of the system, on average it would take more energy to break the key than there is usable energy in the known universe

        A perfect computer can have no entropy change provided it never forgets anything.

        Storing all 2^256 keys would require 2^264 bits. There are estimated to be roughly 10^80 particles in the universe ~ 2^265. It's not immediately obvious to m

    • Re: (Score:3, Informative)

      by meringuoid (568297)
      But they were talking about quantum key exchange. Assuming that they're then using a standard symmetric key to encrypt the link it's still theoretically breakable, just the key exchange that isn't.

      Let the key be at least as long as the message itself; then you have a one-time pad, which is unbreakable.

      • Yes. Exactly. But your key generation has to have the same bandwidth as your data channel.

        When I said standard symmetric key I meant key much shorter than message.

        If they can generate a key at a bit rate sufficient to support video conferencing with a fidelity of no less than 5/6 over standard fiber optic cable then I'm very impressed.

        If their fidelity is lower than that then an attack may be impossible currently but it's not theoretically impossible for someone with a perfect (as far as allowed by the rule

    • The fidelity necessary for QKD to be provably secure depends on the axact protocol used. BB84, the most common protocol, can withstand a 11% error rate. Quantum cloning is one of the most obvious attacks, but not necessarily the best one. Also, as other commenters said, quantum cryptography is only secure if the key is used in a OTP.

  • So, we have quantum computers with quantum networks doing quantum cryptography. What's next, buying music with quantum DRM, i.e. the song is both there and not there until the sound card observes it? ;)

    • We already have that. When you make a purchase from the MAFIAA, you both own it and don't own it at the same time.
  • If it rellies on the concept of "trusted relays", it is not really secure. Point to point cryptography can be secure, but when you start to depend on third parties, how can you be sure?

    • ...when you start to depend on third parties, how can you be sure?

      http://en.wikipedia.org/wiki/Digital_signature [wikipedia.org]

      • Re: (Score:3, Interesting)

        by david_thornley (598059)

        Yeah, but the same crypto that allows digital signatures also allows secure key exchange.

        In other words, although this is an impressive achievement, it isn't clear to me that there's any practical application as yet. Particularly when we consider that modern crypto is almost certainly secure, so that intercepting the bits en route is pointless, and that you don't need crypto over a physically secure route.

        Quantum computation and communications may well be very useful some year, but 2008 isn't it.

        • Yeah, but the same crypto that allows digital signatures also allows secure key exchange.

          In other words, although this is an impressive achievement, it isn't clear to me that there's any practical application as yet. Particularly when we consider that modern crypto is almost certainly secure, so that intercepting the bits en route is pointless, and that you don't need crypto over a physically secure route.

          There's an application: Distribution of the public keys that make digital signatures and secure priva

        • Modern crypto can't warranty the non observation of the signal by a third party.

        • 2009: the year of quantum computation and communication on the desktop!

      • Ok, that link is so far off that I had to check it in order to know that there isn't some relevant info hidden in it. Turns out that it doesn't.

        If you have a cryptography algorithm that depends on thrid parties decoding and reencoding your text, you can't be sure that those third parties won't eveasdrop your plain text. That is simply not secure.

  • Still vulnerable to MITM (Score:4, Insightful)

    by ThreeGigs (239452) on Friday October 10 2008, @08:10AM (#25326745)

    ..." trusted repeater paradigm "...

    Okay, so basically you're only 'secure' up to about 30 miles, and that's only if you have a real, honest to goodness, point to point fiber link. Otherwise they're still converting photons to electrons, and making new photons, at the repeaters.

    It's no more secure than current fiber, except that you've limited the attack vector and locations to known points, namely the repeaters.

    • "no cloning" theorem dictates how repeaters work (Score:5, Informative)

      by Cordath (581672) on Friday October 10 2008, @10:18AM (#25328105)
      Quantum key distribution (QKD) relies on the fact that a single measurement can only reveal partial information about its state. i.e. The same fundamental physical property that makes QKD work also makes it impossible to "read" a photon at a trusted repeater station and then resend an identical copy. This would violate the "no cloning" theorem. Instead, the trusted repeater would have to exchange a key with both the sender and receiver. This obviously requires trust and slows things down, but it's not unreasonable in a European bank network where many banks that both trust each other are physically located within a short distance of each other. (Current QKD is limited to links of distances of about 150 km due to loss in fiber, and the secret key bitrates at these distances are not good.)

      End point to end point QKD is possible with what are called quantum repeaters. In this scheme, the repeater station creates single photon pairs and sends them to the adjacent links in the chain. At each link, bell state measurements are performed that create a daisy-chain of entanglement swapping until, ultimately, the sender and receiver at the two ends of the chain are left with an entangled pair that they can use to create a key. In this scheme, the repeaters actually gain no information about the entangled pair that the sender and receiver wind up with, and the sender and receiver are able to detect tampering just as they can with other forms of QKD. The result is a repeater network over which secure communication is possible even if the repeaters are untrusted. The worst case scenario, theoretically, is that the eavesdropper just cuts the line so that communication isn't possible.

      This technology works experimentally, but will not be practical until quantum memory (i.e. light storage) becomes practical. The problem is that, without memory, each link in the entanglement chain has to receive photons at the same instant in time. With loss happening randomly in all the links, the probability of this happening is no greater than the probability of a photon traveling directly from the sender to the receiver. Ergo, you gain nothing.

      Quantum memory is a hot field of research and several experimental groups have shown promising results using a variety of approaches. In short, QKD will not be limited to trusted relay networks for long.

    • Re:Subspace Encryptions (Score:4, Insightful)

      by jellomizer (103300) on Friday October 10 2008, @07:11AM (#25326283)

      You know, Star Trek is fiction, right? Not all the technology in the Star Trek fictional universe is possible, an some others will come out very soon others probably never.

    • I've always wondered what type of encryption was used in Star Trek episodes when it was announced that there was an encrypted subspace channel for Picard.

      Along similar lines, remember in episode 25 of TOS, where just before beaming down to the planet Captain Kirk opened up a safe in his quarters? I always wondered what the combination was.

    • If you can afford to spend billions of (today's) dollars building these ships, you can afford to send 'em out with a few wowzabytes of random pad.

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