Quantum Communications Questions

Discussion in 'Cyber' started by Technofox, Aug 19, 2016.

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  1. Technofox

    Technofox That Norwegian girl Staff Member Ret. Military Developer

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    As the title notes, I've a question or two about Quantum Communications, or more specifically, their perceived security.

    China recently sent an experimental quantum communications satellite into orbit and is receiving signals from it. It's being billed as "hack proof", but is it really? From what I know and have looked into, Quantum communications have been "hacked":

    http://www.popsci.com/technology/ar...ck-quantum-encryption-scheme-leaving-no-trace

    http://www.techrepublic.com/blog/it...ptography-works-and-by-the-way-its-breakable/

    http://arstechnica.com/science/2011...-cryptography-by-faking-quantum-entanglement/

    http://www.wired.com/2013/06/quantum-cryptography-hack/

    They are more secure, but not unbreakable so that much is likely hyperbole on the part of an overzealous, and ever ignorant media. But adding to this, there are way to guess the encryption keep with a 5/6 fidelity, meaning the key is basically broken - this is called the imperfect Cloning, which, though the No-Cloning Theorem states no perfect key can be reproduced, can create an imperfect key that is so similar that the missing pieces can be uncovered without much effort.

    Another problem is that while the communications themselves may be encrypted by quantum trickery, they can't be read in the same state. They must be converted into plain text, and any plain text, such as this post on AMF, can be intercepted, read or altered.

    With that said, my questions are these.

    Is this unhackable or hyperbole?

    What methods could an adversary leverage to break or negate the effectiveness of quantum encryption and communications?

    Are the methods of breaking quantum encryption, if true, such as high powered lasers, practical?

    Is this Chinese satellite actually the first of its kind? Or have others, perhaps smaller CubeSats been placed into orbit to study the same effects?
     
  2. Blue Marlin

    Blue Marlin 2nd Lieutenant

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    theres no such thing as "unhackable" just harder to get at. i have not looked into quantom computers yet but i have simply been told if you want to hack a quantom computer all you need is another quantom computer.

    using lasers would destroy/damage the machine. even electromagnetic pulses would fry it as it would do to any electrical device. but using another breed of system to get into the same breed is easier said than done. as a new computer comes new encryption methods. the chinese also have been working on their own programming language.
     
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  3. Technofox

    Technofox That Norwegian girl Staff Member Ret. Military Developer

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    I don't believe this part is true, at least not from what I'm reading. Physics was never my best subject.

    Using existing methods, researchers have been able to not only blind the uplinks of quantum communications nodes, rendering them unable to receive communications, as a satellite must do as it's not the origin of the communication, but its relay, but using those same lasers they can actually improve the probability that a low impulse laser, one putting out a single photon at a time, can generate the same photon the quantum communicator is receiving or sending.

    So a satellite can either be blinded to prevent it from receiving signals, especially jamming it or its communications can be intercepted from the downlink.

    Wired has a great article on the topic.

    Where we are in agreement is that to break the encryption encoded on a photon generated by a low impulse laser, you'd likely need a quantum computer to decode it. Just not one to gather the information itself.

    The Chinese satellite is both encoding and transmitting those signals, but it's doing so via entanglement - near instantaneous generation of two like photons. The laser trick should still work, but I wonder what other methods could be used to gain access to the photon generated?
     
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