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Hackers Eavesdrop On Quantum Crypto With Lasers 161 161

Martin Hellman writes "According to an article in Nature magazine, quantum hackers have performed the first 'invisible' attack on two commercial quantum cryptographic systems. By using lasers on the systems — which use quantum states of light to encrypt information for transmission —' they have fully cracked their encryption keys, yet left no trace of the hack.'"
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Hackers Eavesdrop On Quantum Crypto With Lasers

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  • Re:pwned (Score:5, Informative)

    by neumayr (819083) on Monday August 30, 2010 @04:59AM (#33413178)
    Not really. From the article:

    "We have exploited a purely technological loophole that turns a quantum cryptographic system into a classical system, without anyone noticing," says Makarov.

  • Re:Lessons (Score:5, Informative)

    by neumayr (819083) on Monday August 30, 2010 @05:03AM (#33413192)
    The underlying principle still is valid, those people exploited a technical loophole - in a process that's part of

    [..] years of dedicated effort in an open environment.

  • Re:pwned (Score:5, Informative)

    by Unipuma (532655) on Monday August 30, 2010 @05:04AM (#33413196)

    If you read the article, you'll notice that the 'hack' is a classic man in the middle attack, and the receiving end can receive both classic and quantum messages. The man in the middle (after reading the quantum message) passes it on as a classic message, and the receiving device does not give a warning that the message received is a classic message, instead of a quantum message.

    So it's really an design error on the device side, not a true hack in that quantum states were undisturbed regardless of reading them.

  • not really that bad (Score:5, Informative)

    by mogness (1697042) on Monday August 30, 2010 @05:06AM (#33413204) Homepage
    The problem isn't really with quantum encryption, it's with the technical implementation. And anyway, according to the article, they've already figured out a way to detect the hack and defeat it, so it's still pretty solid.

    Makorov informed both companies of the details of the hack before publishing, so that patches could made, avoiding any possible security risk.

  • by romiz (757548) on Monday August 30, 2010 @05:14AM (#33413232)
    There are some photographs of the hacked hardware and the hacking tools on the page [] of the researchers.
  • by tibit (1762298) on Monday August 30, 2010 @08:42AM (#33413858)

    You would be right if you weren't so wrong :(

    The problem with torture is that it has a way of making up information where there is none. If you're convinced your guy has the information, but he doesn't, then torture is an element of a random story generator. And there's pretty much no way of telling the quality of information that you receive.

    Case in point: I think that a big problem with some Gitmo inmates is that they were set up by bounty hunters, and they are simply wrong people in a wrong place at the wrong time. Torture is useless here, because they know nothing in the first place, and the "solid information" they provide is solidly random, if that.

  • by PseudonymousBraveguy (1857734) on Monday August 30, 2010 @09:20AM (#33414180)
    Actually quantum crypto requires Bob to communicate with Alice over an authenticated channel anyways (e.g. to check which polarisation filter was used for each measurement, and to check for eavesdropper). This channel can trivially be used to signal failures and/or attacs. (However, quantum crypto does not tell you where to find a perfectly secure authenticated channel)
  • by Vadim Makarov (529622) <> on Monday August 30, 2010 @06:39PM (#33420894) Homepage
    Good. We are not controlling Bob's basis: he chooses his detection basis randomly. What we do is to send a bright-light state that does not cause a detection event if Bob chooses a basis not matching Alice's, but causes a detection event in a specific detector if Bob chooses the same basis as Eve. See figure 2 in the paper [] for illustration. Thus, half the time our bright-light state failes to induce any detection, which translates to just 50% detection efficiency. This would be a problem if Bob's photon detectors (unblinded, not under attack) were 100% efficient and the transmission fibre were lossless, which is however not the case. The photon detectors are normally only about 10% efficient, and there is typically a few dB loss in the fibre between Alice and Bob. Thus Eve can easily hide her 50% (in)efficiency in all practical cases.

    In schemes where Bob uses "passive basis choice" (not in commercial systems but in many research setups) we can choose the detection basis for Bob and have 100% click efficiency.
  • by Vadim Makarov (529622) <> on Monday August 30, 2010 @07:52PM (#33421502) Homepage
    Your first item is correct, however for the second one I think you need to study a good description of the QKD protocol.

    The QKD protocol is designed to cope with a huge bit loss, both due to detector inefficiency and the loss in the fiber line; in fact, in a typical setup only 1 in 1000 Alice's photon's may be detected by Bob. The loss in the line is the killer item: the best optical fiber is has loss about 0.2 dB per km. This means over 50 km, nine out of ten photons sent by Alice will be lost. (In our attack Eve can just gain all this loss to her advantage, by placing her intercept unit close to Alice and getting all ten photons.) Other losses and inefficiencies come in addition to the line loss.

    The transmitter (Alice) and the receiver (Bob) cannot synchronize their basis selection in advance, but they have to choose them randomly and independently (so that Eve does not know either if the bases), otherwise QKD just cannot be secure. They synchronize the bases only after the photon transmission.

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