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Security Encryption Science

Researchers Simplify Quantum Cryptography 106

Posted by kdawson from the again-with-the-bob-and-alice dept.
Stony Stevenson writes "Quantum cryptography, the most secure method of transmitting data, has taken a step closer to mainstream viability with a technique that simplifies the distribution of keys. Researchers at NIST claim that the new 'quantum key distribution' method minimizes the required number of detectors, the most costly components in quantum crypto. Four single-photon detectors are usually required (these cost $20K to $50K each) to send and decode cryptography keys. In the new method, the researchers designed an optical component that reduces the required number of detectors to two. (The article mentions that in later refinements to the published work, they have reduced the requirement to one detector.) The researchers concede that their minimum-detector arrangement cuts transmission rates but point out that the system still works at broadband speeds."
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Researchers Simplify Quantum Cryptography More

Researchers Simplify Quantum Cryptography

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  • Quantum Post! (Score:5, Funny)

    by Majik Sheff ( 930627 ) on Monday June 02, 2008 @11:36PM (#23634813) Journal
    Either this post is first or it isn't. I won't know until I press submit.

    • Re:Quantum Post! (Score:5, Funny)

      by FrYGuY101 ( 770432 ) on Tuesday June 03, 2008 @12:49AM (#23635121) Journal

      Either this post is first or it isn't. I won't know until I press submit.
      No fair! You changed the outcome by posting it!
    • Actually... This could have been the first post, not the first post, or both. And even though you had pressed submit, you probably wouldn't be able to find out anyway.

      • Re: (Score:2, Interesting)

        by Impy the Impiuos Imp ( 442658 )
        Not immediately, I suppose. It's interesting to note that a proper database system would discrete-ize the posting numbers to arrive at a definite first post, even though relativity makes a mockery of first posts.

        Hey wait, that shouldn't be possible.

        > Quantum cryptography, the most secure method of transmitting data,

        Technically it would only be tied at best with a one-time pad, and, at worst, slightly less secure. I wonder if it has codes that could be cracked by social engineering, as one time pad's co
    • Well I won't know until I observe it.
  • Anyone care to explain why anyone should use this? So it's 100% random...why cares? So equation and clock based pseudo random based encrptions can technically be predicted cuz they're not 100% random. But nobody ever knows the exact equation AND exact millisecond it was calculated to generate the key so noobdy can predict it. I don't think it's any better. It's just a product they're pushing with some ridiculous statement like "but it's better cuz it's completely random!" and never back it up with any

    • Re: (Score:2, Informative)

      by Anonymous Coward
      It is impossible to crack because there is no way to decode it without the right key. Algorithms like RSA or DES can be brute forced with enough horse power, for instance, when the quantum computer is invented it could make short work of them. Quantum cryptology will be the only defense.

      • when the quantum computer is invented
        But will it run Crysis?

    • Re:what's the big deal (Score:5, Informative)

      by BadAnalogyGuy ( 945258 ) <BadAnalogyGuy@gmail.com> on Tuesday June 03, 2008 @12:00AM (#23634917)
      The big deal is that the cracking time for non-quantum algorithms reduces to O(n) for length n keys. OTOH, for quantum encryption, the cracking time minimum threshold is O(n^n) for length n keys. Hyperbolically, the linear analog is also true in that with quantum decryption, it is possible to crack non-quantum algorithms in O(n) time (again for length n keys), but quantum algorithms require O(n^n) to decrypt. Note that without the correct key, the quantum algorithm requires O(n^n) regardless of whether the cracker is employing spherical numerical analysis techniques or advanced quantum distribution array matrices.

      The fact of the matter is that quantum encryption provides much greater security than standard algorithmic encryption.

      • Re:what's the big deal (Score:5, Interesting)

        by Anonymous Coward on Tuesday June 03, 2008 @12:22AM (#23635029)
        You also failed to mention that it is impossible to eavesdrop on the communication of the keys. This is probably the most important part because it can make one time pad encryption useful on computer networks. Without quantum cryptography, your one time pad is only as safe as how you send it (RSA encryption, chaos encryption, snail mail). Additionally, quantum cryptography can't be reverse engineered to find the algorithm for your one time pad.

        This is all nice, but it is going to be tricky to implement it in the future. How do you send a photon from one computer to another a long distance away without using repeaters or branches? It will be a little tricky. Would this require a fiber optic connection between every computer that wants to communicate with quantum encryption? Or can you adjust the medium so that photons are transmitted and branched undisturbed?

        • Re:what's the big deal (Score:4, Informative)

          by mapsjanhere ( 1130359 ) on Tuesday June 03, 2008 @09:01AM (#23637649)
          People are mixing up two different things here - quantum transmission, the one you can't read unnoticed, and encryption/decryption using quantum computers and algorithms.
          The first one has been demonstrated, and works over limited distances.
          The second is an "advanced concept", right next to fusion reactors.

        • Re: (Score:2)

          by kmac06 ( 608921 )

          How do you send a photon from one computer to another a long distance away without using repeaters or branches?

          You don't. You just use branches and repeaters! It sounds counter-intuitive, but you can do something called entanglement swapping [wikipedia.org] to send the quantum state from Alice to Bob through Charlie, without Charlie changing (or even being able to detect) the state Alice sent.

          Also you can control/change the path of the photon using electro-optical controls without changing it's state (or at least without changing the part of the state that carries the information), though this would likely be more difficult/exp

          • Mod parent up (Score:3, Informative)

            by bh_doc ( 930270 )

            I was just discussing entanglement swapping with my supervisor the other day, actually. Neat concept. Roughly, person A has two entangled photons, A1 and A2. Person B has similar, B1 and B2. They both send their 1 photons to C. C entangles A1 and B1 and because of this, A2 and B2 are now entangled. This can then be used to generate a bit of a key.

            We were actually discussing it in the context of producing entanglement between ions (good for storage/memory) and photons (good for transmission), since in the

      • Re: (Score:3, Funny)

        by SeekerDarksteel ( 896422 )
        Plus with quantum encryption you can utilize lunar wainshafts to feed the unilatral phase dectractors and Karnot-Graham meters.

        ...

      • Re: (Score:3, Insightful)

        by spazdor ( 902907 )

        spherical numerical analysis techniques or advanced quantum distribution array matrices.


        I was with you up until about there. It occurs to me that there are any number of mathematical terms that could be combined at random to induce the same effect in me, and I wonder if this is true of all the people who modded you up.

        I think i'm just gonna take your word for it. :)

        • Re:what's the big deal (Score:4, Funny)

          by MrMr ( 219533 ) on Tuesday June 03, 2008 @02:12AM (#23635411)
          It's not so hard, let me explain:
          spherical numerical analysis techniques: That is standard maths; If you need to compute something involving for instance a cow, you start with "Assume a spherical cow with radius R".
          advanced quantum distribution array matrices: That just your normal quantum distribution array matrices but with the new icons and toolbar.

          • Re: (Score:1)

            by redxxx ( 1194349 )
            You left out the new 'quantum bar'. It's really cool because when you click the little star, it creates a quantum super state where the address is simultaneously bookmarked and not bookmarked. A lot of people have been complaining about all the extra clutter, but that's just because they are observing the results.

          • "Assume a spherical cow with radius R".
            You're leaving out the most crucial part:

            Uniform density!

      • Re: (Score:2)

        by gweihir ( 88907 )
        The fact of the matter is that quantum encryption provides much greater security than standard algorithmic encryption.

        In your dreams. No quantum computer exists that can break encryption used today by a very, very large margin. It seems doubtful whether researchers can get beyond a few bits at all, let alone scale up to a few thousands. Presently this is all hype to get research money. There have been much more similar things that failed and only very few that deliverd on their claims.

        • Re: (Score:1, Insightful)

          by devman ( 1163205 )
          The reason governments throw money at it is because whoever can build the first working one would theoretically have the keys to the kingdom. If a working quantum computer existed (and worked as theorized) suddenly secure communication over the internet would be a liability, thats assuming if one ever gets built (and works) and the public knows about it.

      • Re: (Score:1)

        by Tolkien ( 664315 )
        Where's the car, Mr. BadAnalogyGuy?

      • Re: (Score:2)

        by kmac06 ( 608921 )
        Nonsense. Quantum encryption, when properly implemented, cannot be cracked. Period. If you have a perfectly good and fast quantum computer, you still could not crack quantum encryption. RSA can be broken using Shor's algorithm, but that is O(log(n)^3), not O(n). And if you don't have a quantum computer lying around, then it's a lot worse than that.

        Parent shouldn't be modded informative, just about everything he said was wrong.

    • Re:what's the big deal (Score:5, Informative)

      by Inf0phreak ( 627499 ) on Tuesday June 03, 2008 @12:03AM (#23634935)
      I think you've misunderstood something. "Quantum encryption" is something of a misnomer. It's actually a physical process that can be used by Alice and Bob to establish a commonly shared secret that is random (and unknown to even Alice and Bob before the process starts). This secret is then typically used as a one-time pad [wikipedia.org].
      • Here's something I've never understood. Alice prepares a one-time pad and sends it along using this quantum dealie. Eve intercepts it. Now supposedly this thing changes every time someone observes it, but could Eve just generate a new one based on the data she acquired? Alice created one 'from scratch', why can't Eve?

        • Re: (Score:2)

          by Firehed ( 942385 )
          Presumably because the one-time pad is your decryption key. Encryption wouldn't be especially useful if you could just put in a password (not "the" password, but "a" password) and unlock the secrets, would it?

          That's my best guess, I've never really understood the theory either. It IS quantum physics, after all.

        • Re:what's the big deal (Score:5, Informative)

          by SeekerDarksteel ( 896422 ) on Tuesday June 03, 2008 @12:46AM (#23635111)
          The reason Eve can't just generate a new pad is because there are two methods of generating a photon and two methods of measuring a photon. Each method of generating a photon has a matched way of measuring it. If you use the matched measurement method you correctly get the bit Alice sent. If you use the incorrect method you get a random 0 or 1 no matter what bit Alice sent. Eve (and Bob too) has no way of telling which method Alice used. In quantum key distribution, after sending the photons, Alice would contact Bob over a different channel. They would tell which method they used, and if they used matching methods keep that bit. If they used different methods they would throw out the bit. If Eve regenerated the bits, she could not have used the same methods as Alice since she doesnt know which methods were used. So Alice and Bob's keys won't match up which will result in any information passed between them to be undecodable and they will know someone eavesdropped.

          Quantum Key Distribution is, in its most naive form, still vulnerable to man in the middle attacks. It makes it a little more difficult because you must be able to intercept information on two different channels (the quantum channel and the classical electronic channel), but it is still doable. (There are, however, cryptographic methods of detecting man in the middle attacks, but thats a subject for another time).

        • Re: (Score:2)

          by Urkki ( 668283 )
          This is how I understand it: In normal cryptography, you have to worry about "the man in the middle" intercepting the message and then cracking it at their leisure. In quantum crypto, "the man in the middle" can't do this. They need the keys beforehand to even record the message. And another thing is, they can't just eavesdrop passively, they must do actual "man in the middle", ie. intercept the message and re-send it in real time.

          Somebody correct me if I'm badly mistaken...

        • Re: (Score:3, Interesting)

          by locofungus ( 179280 )
          Here's something I've never understood. Alice prepares a one-time pad and sends it along using this quantum dealie. Eve intercepts it. Now supposedly this thing changes every time someone observes it, but could Eve just generate a new one based on the data she acquired? Alice created one 'from scratch', why can't Eve?

          Lookup quantum cloning and the "no cloning theorem".

          But basically (and this is a naive implementation that won't actually work), Alice transmits to Bob using linearly polarized photons. Now, if

          • Actually, in the naive scheme outlined above I think Eve can do: a|H> + b|V> => a|HH> + b|VV>, store her photon, wait for Bob to measure, eavesdrop the message from Bob to Alice and then make the same measurement on her stored photon.

            Actually, the message telling which bits were send and/or measured at a 45% angle is only exchanged after Bob has measured the quantum bits. So, even can't just store them, measure them and re-inject them after the fact.

            So, rather than just eavesdropping the message from Bob to Alice, she would actually need to destructively intercept it and change it.

            • Actually, the message telling which bits were send and/or measured at a 45% angle is only exchanged after Bob has measured the quantum bits. So, even can't just store them, measure them and re-inject them after the fact.

              So, rather than just eavesdropping the message from Bob to Alice, she would actually need to destructively intercept it and change it.

              Eve isn't intercepting the bits. She's creating a pair of correlated photons without actually making any measurement. She sends one on to Bob and stores the o
        • Grrr. &lt; needed :-(

          Here's something I've never understood. Alice prepares a one-time pad and sends it along using this quantum dealie. Eve intercepts it. Now supposedly this thing changes every time someone observes it, but could Eve just generate a new one based on the data she acquired? Alice created one 'from scratch', why can't Eve?

          Lookup quantum cloning and the "no cloning theorem".

          But basically (and this is a naive implementation that won't actually work), Alice transmits to Bob using linearly p
      • yeah, so it's completely random and comes out of nowhere. But a gigantic equation based on an exact millisecond on the computer's clock might as well have come from nowhere too cuz nobody can record or measure that. But the next couple replies actually make sense (almost) about how it prevents eavesdropping. I still don't buy the completely made up, cat in a box, quantum flux until someone "measures it" even though measures it doesn't make sense in the tradition sense and is unproven in the absolute mole
        • You don't transmit the message using QC, you transmit a OTP. So if Eve does intercept it then all she gets is a bunch of random bits, Alice and Bob detect the interception, throw the OTP away and start again.

          The best that Eve can do is a DOS attack.

          Tim.
    • Quantum cryptography is supposed to provide secrecy by detecting eavesdroppers, since other parties observing your conversation should disturb some physical properties that you can subsequently measure.

    • Impossible to eavesdrop, otherwise, a big yawn (Score:5, Interesting)

      by Mathinker ( 909784 ) on Tuesday June 03, 2008 @12:07AM (#23634955) Journal
      The sexy part is that if there is a third party who tries to eavesdrop, the attempt will both fail and can be detected by the two communicating parties, and that the security of quantum cryptography has nothing to do with the lack of ability to factor large numbers, but is instead based on physical principles (quantum mechanics). Of course, the sensitivity to eavesdropping means that the system is probably vulnerable to a denial of service attack, depending on how the two communicating parties relate to eavesdropping.

      Otherwise, you are perfectly correct. Many cryptographers, including Bruce Schneier, believe that quantum cryptography is a solution to the wrong problem. Nowadays, most probably, the least secure part of your communication system isn't in your key distribution scheme, but is somewhere else --- like in social engineering, or the computer systems which deal with the decrypted cleartext.

      • Re: (Score:2)

        by Tom ( 822 )

        Otherwise, you are perfectly correct. Many cryptographers, including Bruce Schneier, believe that quantum cryptography is a solution to the wrong problem. Nowadays, most probably, the least secure part of your communication system isn't in your key distribution scheme, but is somewhere else --- like in social engineering, or the computer systems which deal with the decrypted cleartext.

        I disagree with Bruce on this, no matter how much I respect him. Once we have a reliable crypto scheme, people will stop looking at the technology when there's a failure, and start looking at the real issues. And I'm pessimist enough to believe that nothing else, no amount of education, training or awareness, will make them do that.

    • Re: (Score:2)

      by gweihir ( 88907 )
      There is an even bigger problem with quantum ''encryption'': The pysical models are only ever exact to some degree. It is quite possible that some minor, not yet discoverd, effect exists that completely breaks security. If you really want to be secure, definitely stick to the stuff we understand.
  • Is there anywhere in the world actually using this sort of technology? Is it used in the military at all?

    • Not much (Score:3, Informative)

      by Mathinker ( 909784 )
      From Wikipedia:

      Quantum encryption technology provided by the Swiss company Id Quantique was used in the Swiss canton (state) of Geneva to transmit ballot results to the capitol in the national election occurring on Oct. 21, 2007.[8]

      In 2004, the world's first bank transfer using quantum cryptography was carried in Vienna. An important cheque, which needed absolute security, was transmitted from the Mayor of the city to an Austrian bank.[9]

      Both of these look like special uses set up for publicity by vendors.

      • Re: (Score:2)

        by gweihir ( 88907 )
        Both of these look like special uses set up for publicity by vendors.

        They are. Nobody competent would use quantum techniques for things that really need to be secure. The physics is not that well established, for one thing, leading to an unknown risks. Sure, the properties look nice, but when was the last time a fundamental physical theory turned out to be not quite accurate? Yes, that is true, when the current theory replaced the last one. That has happened so far to every theory except the respective curr

    • I doubt it. (Score:1, Redundant)

      by jd ( 1658 )
      You can achieve comparable security using Byzantine methods to split a one-time encryption pad into relatively secure fragments. Since the fragments can be reordered and then randomly embedded in the data, you can achieve everything boasted for quantum encryption but using methods tried-and-tested.
    • Alice in Northern Virginia talks to Bob in DC. And elsewhere...

      ...For several years now.

      Google it...

      or check this: http://it.slashdot.org/article.pl?sid=06/12/13/1458238&from=rss [slashdot.org]

  • Yay! Saved! (Score:2, Funny)

    by SEWilco ( 27983 )
    With this simplification, thousands of cats are saved from having to deliver code keys.

  • Oblig XKCD (Score:3, Funny)

    by azakem ( 924479 ) on Tuesday June 03, 2008 @12:06AM (#23634947)
    Every time I hear about Alice and Bob, I now think of this [xkcd.com]

  • Broadband Speeds (Score:2, Interesting)

    by enoz ( 1181117 )
    Describing the rate as "Broadband Speeds" is about as useful as describing the performance of a supercar as "roadworthy" (there's your car analogy).

    For reference, in Australia not only does the incumbent Telco consider 256/64kbps to be broadband, but they also describe it as "Fast [bigpond.com]".

    • Describing the rate as "Broadband Speeds" is about as useful as describing the performance of a supercar as "roadworthy" (there's your car analogy).
      Quantum cryptography doesn't need to be all that fast.
      The whole point is to be able to securely pass an encryption key.
      Then you can encrypt and use any method you like for transporting the encrypted data.
      Whether it's Australian 'fast', Internet2 fast, or a stationwagon full of Terabyte hard drives fast.

  • Broadband? (Score:2, Insightful)

    by Tubal-Cain ( 1289912 )
    What speeds are they calling broadband? 200Kbps?

  • Not the most secure (Score:3, Insightful)

    by BlueParrot ( 965239 ) on Tuesday June 03, 2008 @12:33AM (#23635061)
    There is only one cryptography scheme with proven secrecy, and that is the one time pad. Even if you assume no errors occur in its implementation, no physicist can guarantee there will never be discovered a way to eavesdrop on transmissions that use Quantum Cryptography. In contrast with the one time pad a Mathematician can more or less prove, at least to the extent you can prove anything at all, that eavesdropping is only possible if the implementation is flawed.

    In practice none of this is relevant since the hassles associated with correctly implementing either QC or a OTP are sufficiently large that for most applications they are both inferior to public key cryptography and symmetric ciphers. There are some exceptions, but the only way you could possibly justify describing quantum cryptography as "the most secure way to transmit data" would be by ignoring so many aspects of information security that it will have no relevance to practical applications.

    • Re: (Score:3, Informative)

      by Cairnarvon ( 901868 )
      -1 Failed Attempt at Sounding Insightful.
      Quantum cryptography schemes are guaranteed to inform both Alice and Bob if their communication is intercepted. That's the entire point, and what has everyone so excited about quantum cryptography in the first place. Secrecy in the sense of undecryptability isn't the point of quantum cryptography (as data isn't even *encrypted* in the classical sense), just certainty that there are no eavesdroppers.
      Your post just suggests that you haven't actually read anything about

      • Re: (Score:3, Interesting)

        by Creepy Crawler ( 680178 )
        Ok. What is an observer?

        Or better yet, what would happen if some new device could record without observing?

        ---Quantum cryptography isn't a cipher. It's a method of transmitting data, which does one specific thing, which is guarantee that you'll be able to tell if people have attempted to eavesdrop. It's not a complete cryptosystem; it's not meant to be. It's meant to be just one component of cryptosystems, and in doing what it does, it's provably secure in the sense that secure is being used here.

        Of course

        • Ok. What is an observer?

          Or better yet, what would happen if some new device could record without observing?

          I spend most of my time debating creationists, not laypersons who misunderstand quantum physics, but I bet physicists get as tired of shouting "IT DOESN'T WORK LIKE THAT" at people like you as I do at creationists.

          It's probably pretty accurate though, but is it accurate to trust?

          You'll remember Feynman once compared our understanding of quantum physics to measuring the distance between New York a

          • Re: (Score:2)

            by blueg3 ( 192743 )

            I spend most of my time debating creationists, not laypersons who misunderstand quantum physics, but I bet physicists get as tired of shouting "IT DOESN'T WORK LIKE THAT" at people like you as I do at creationists.

            All the time.

            You'll remember Feynman once compared our understanding of quantum physics to measuring the distance between New York and Los Angeles to within the width of a human hair. I'd say anything with that kind of predictive power is probably accurate enough to trust your life with.

            That's actually quantum electrodynamics. QED was "solved" by Feynman using approximations that involve shady cancellations of infinite quantities. It's accepted as an approximate solution, but the quality of the approximation is good. Simple quantum mechanics, like what quantum cryptography is based on, is much better-understood.

        • Or better yet, what would happen if some new device could record without observing?

          "record without observing" doesn't make sense. In the words of Pauli, "That's not right. That's not even wrong." But trying to guess that you mean "observe without affecting in any way".

          Then you can violate causality. Give me a device that can "record without observing" and I'll build you a device to communicate faster than the speed of light.

          Tim.

    • There is only one cryptography scheme with proven secrecy, and that is the one time pad. Even if you assume no errors occur in its implementation, no physicist can guarantee there will never be discovered a way to eavesdrop on transmissions that use Quantum Cryptography. In contrast with the one time pad a Mathematician can more or less prove, at least to the extent you can prove anything at all, that eavesdropping is only possible if the implementation is flawed.

      You are comparing apples with oranges. The b

      • Re: (Score:3, Interesting)

        by Creepy Crawler ( 680178 )
        ---How is your mathemetician going to distribute his one time pad?

        A one time pad guarantees perfect secrecy. A QC channel allows secrecy as any "listening" devices become in part with the system, thereby allowing detection.

        I do think this is a bit excessive by stating.. Data is always time-dependent. Therefore, we only need protect data for X amount of years.

        What combination of encryption technologies can we use to make the data physically hard to crack? We need a multi-tiered encryption setup that uses mul

      • Re: (Score:1, Insightful)

        by Anonymous Coward

        How is your mathemetician going to distribute his one time pad?

        The same way you are going to tell the receiver of the QC message to use Quantum cryptography in the first place.

        Lots of people seem to have this confused. Quantum cryptography does NOT give you a way to do secure key exchange without meeting the person you are going to communicate with. If you think about it for a second you will realize that this CANNOT be done no matter what encryption scheme, and no matter what "spooky action at a distance"

    • You do realize that QC is just a method of securly distributing a one-time-pad between two endpoints, right? They don't use the photons to send the message data, that gets XORed later and sent via normal channels. So if everyone is wrong about quantum mechanics translates directly to "the OTP implementation is flawed". While OTPs are hard to implement (Where did I put that onionpaper again?) the whole point of developing QC is to get to the point someday where it IS practical/hasslefree to distribute the
    • is people. Either reusing an OTP or failing to RTFM for the QC equipment. It doesn't really matter that it would take e.g. the NSA longer than the time to the heat death of the universe to "crack" a cipher if $100k in a suitcase can "crack" Alice.

      For a really really good look at security, try to track down the earliest black+white TV series of Mission Impossible - (almost no gadgets, lots of neat social engineering).

      Andy

    • The one-time pad requires a shared-secret key in order to be able to encode and decode encrypted messages. Sharing the key securely becomes a huge logistical problem.

      Quantum cryptography promises, through quantum theory, that anyone trying to skim data from a secure channel ultimately corrupts it. So by measuring the noise level in the channel you can detect an eavesdropper.

      A typical Quantum cryptography scheme requires two channels. One of the channels is a classical channel, like the internet,

    • Re: (Score:2)

      by blueg3 ( 192743 )
      Of course, with encrypted data, you need to ensure that nobody in the future will be able to defeat the cryptography.

      The process of quantum "cryptography" is such that you need to ensure that nobody *now* (when you are transmitting the data) will be able to eavesdrop successfully.

  • Why is this practical? (Score:4, Insightful)

    by Johnno74 ( 252399 ) on Tuesday June 03, 2008 @12:55AM (#23635161)
    I'm all for R&D into pure science, and I'm not bagging the concept of quantum cryptography, but why does this need to be a commercial product?

    Is there really anyone out there paranoid enough to need/want this besides various three-letter agencies? Maybe this is proveably secure, we think, but what is more likely - Someone finds a loophole in the very weird world of quantum mechanics that makes quantum cryptography as we know it obsolite, or someone figures out a way to find prime factors of obsenely large numbers in a reasonable time.

    This article is about how it may be possible have a quantum crypto setup with a bandwidth of maybe 1024kbps by spending only $20k-$50k on one component to the system. I bet there is a lot of other components.
    Compare this with a basic commodity PC, which can could encrypt 1024kbps using AES with ridiculous ease.

    • Re: (Score:3, Insightful)

      by mrcaseyj ( 902945 )
      I was thinking that it would be foolhardy to trust that some discovery in quantum physics would not render quantum cryptography insecure. But then I realized two things. First, you can always just use QC to wrap conventional cryptography so you get the security of both. Second, conventional cryptography can be eavesdropped on and recorded to be broken someday when weaknesses or more computational power is available. With QC your communications can't even be recorded for future breaking until some new physic

    • but what is more likely - Someone finds a loophole in the very weird world of quantum mechanics that makes quantum cryptography as we know it obsolite, or someone figures out a way to find prime factors of obsenely large numbers in a reasonable time.

      Given that we don't know it makes sense to have both.

      Advances in quantum computing may make the factoring problem an easy one.

      Of course the commercial applications are rather niche right now and cost is no small part of that, but how many things often start that

    • Re: (Score:1)

      by MobyDisk ( 75490 )
      The part tht scares me isn't the power of quantum cryptography. It's the power of a quantum computer to decrypt classical cryptography. It really does look like the end to privacy might be just around the corner.
  • That's a relief. I was worried there for a while.

  • ...quantum cryptography now requires 30% less cats and 46% fewer radioactive isotopes.

  • Article Summary states "Four single-photon detectors are usually required (these cost $20K to $50K each)"

    sounds expensive.

    except, the real article states: "Bob uses four single-photon detectors, costing approximately $5,000-$20,000 each."

    still pretty expensive, but it sounds like you could have a working one of these for only 10k in detectors!

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