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Encryption Security Science

Using Diamonds to Create Unhackable Code 363

Posted by Zonk from the lol-hi-no-1-can-r34d-th1s dept.
IAmTheDave writes "Researchers at Melbourne University have grown diamond particles 1/1000 of a millimetre on optical fibres which they can use to transmit single photons of light at a time. The diamonds are grown on the optical fiber by raining carbon molecules onto the tip of the fiber. They claim that by transmitting information in single photons, any interception of transmitted photons will be useless to the interceptor, and thus the message will be completely unhackable. Transmission speeds are currently slow - 120km/h, but are expected to speed up."
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Using Diamonds to Create Unhackable Code More

Using Diamonds to Create Unhackable Code

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  • That's unhackable TRANSMISSIONS, not code (Score:5, Informative)

    by Chas ( 5144 ) on Friday April 29, 2005 @10:27PM (#12389933) Homepage Journal
    Jeeze.
    • The headline probably means code defined as "a system of signals, such as sounds, light flashes, or flags, used to send messages." Rather than computer code.
    • no, no such thing as "unhackable"

      time and time again we've been shown this to be false.

      it may take time/energy/effort etc but it's clearly possible. always.

    • Re:That's unhackable TRANSMISSIONS, not code (Score:5, Insightful)

      by nametaken ( 610866 ) on Saturday April 30, 2005 @03:37AM (#12390961)

      In light of the fact that we just found the "biggest compromise in history" of secure data was perpetrated by idiot employees selling peoples profiles for $10 (USD) a pop, I'm less worried about unhackable transmissions and more worried about the people at each end.

      Lets remember to call our banks.
    • You know, by code he means "an encoding," not "a programming language snippet."

  • Now for my master plan... (Score:5, Funny)

    by Bananatree3 ( 872975 ) on Friday April 29, 2005 @10:27PM (#12389934)
    Stretch 3000 miles of this across the atlantic, set up a secret recieving station on the African coast, and voila! One secret, untappable method for my world takeover, I mean, world communication plan!

  • "Unhackable Code"? (Score:5, Informative)

    by cbrocious ( 764766 ) on Friday April 29, 2005 @10:28PM (#12389936) Homepage
    This is far from an "unhackable code". In fact, it's not even a code. Please stop thinking that "quantum cryptography" is a form of cryptography. It's simply an interception-resistant media.

    • Re:"Unhackable Code"? (Score:5, Informative)

      by hotspotbloc ( 767418 ) on Friday April 29, 2005 @10:33PM (#12389967) Homepage Journal
      Exactly. When it's too tough to crack the technology then it's time to use social engineering or a key capture hardware device built into a keyboard.

      There is nothing unhackable.

      • Re:"Unhackable Code"? (Score:5, Informative)

        by cbrocious ( 764766 ) on Friday April 29, 2005 @10:37PM (#12389996) Homepage
        Speaking from the standpoint of someone who does a lot of reverse-engineering (PyMusique/pyTunes was my baby) I'd say that 99% of the time, neither of those methods are neccesary. Usually you can get what you need from either the source or destination directly. Most people seem to overestimate security in computer systems. I just can't wait for "quantum cryptography" to be used for DRM keys so we can have a bit of fun ;)

      • Re:"Unhackable Code"? (Score:5, Interesting)

        by Anonymous Luddite ( 808273 ) on Friday April 29, 2005 @10:55PM (#12390084)
        >> There is nothing unhackable.

        and if it's difficult to hack the transmission media, there is probably cleartext versions of the transmission at either end.

        "un-crackable" transmission will just change the point of attack...

      • Re:"Unhackable Code"? (Score:5, Insightful)

        by xiphoris ( 839465 ) on Friday April 29, 2005 @11:14PM (#12390176) Homepage
        Mod parent and grandparent down. Quantum Cryptography is indeed real cryptography. It uses the encryption system known as the One Time Pad [wikipedia.org]. The "Quantum" aspect of it is used in transmission (really, creation) of the random pad on both sides of the communications line.

        There is nothing unhackable.

        Perhaps, but information encrypted with quantum cryptography is un-interceptable. Because of the way a one time pad works, you have no way to verify that you've cracked a message -- any "decrypted" result is the same as any other.

        This is distinct from other encryption methods, which use complicated math to encrypt and decrypt things.

        A one-time pad is merely a block of random data. You XOR your pad with your plaintext to get ciphertext. With a given ciphertext block, you have no way to verify what the correct plaintext is. For example, if I have a ciphertext message: ABCD, that could just as equally be the plaintext HELO as ROFL.

        Quantum cryptography is the usage of quantum mechanisms to generate the same random data at two different locations. Because of properties of quantum physics that I don't personally understand, interception of that quantum data is impossible.

        But no, quantum cryptography is not breakable because it's impossible to know whether you have the correct plaintext, and it's impossible to get the one-time pad from the quantum transmission line (physics guarantees it). In other encryption systems, you know mathematically whether you have discovered the "key". The ciphertext of a one-time-pad, according to information theory (and the assumption that your pad is made of truly random data), provides you absolutely no information about the pad or the plaintext.

        See more here: http://en.wikipedia.org/wiki/Quantum_cryptography [wikipedia.org]
        • I would be cautious about making claims as to what "physics" does and does not guarantee. "Physics" has guaranteed lots of things throughout history that it turns out to be "not quite right". Keep in mind that it took years before the majority of physicists agreed with Eistein's conclusions on relativity. Current experimentation my lead one to draw certain conclusions about the natural world, but the conclusions may not always be 100% correct.

          • Re:"Unhackable Code"? (Score:4, Informative)

            by tbo ( 35008 ) on Saturday April 30, 2005 @03:57AM (#12391023) Journal
            Summary: parent poster is being a twit.

            Long version:
            First, let's clarify what it means to say that "physics" guarantees that your quantum key distribution (QKD) system is unbreakable. Given a perfect implementation of the QKD protocol, or at least an implementation where the errors are within certain bounds and you haven't done anything stupid like reusing your OTP, you are guaranteed security if quantum mechanics is correct.

            What do I mean by correct? I mean that quantum mechanics correctly describes the relevant systems--systems to which it is currently considered applicable.

            We have many good reasons to believe quantum mechanics is correct. Its relativistic extension, QED, has given us some of the most accurately-verified theoretical predictions ever. Notable objections to the theory (such as the famous paper by Einstein, Podolsky, and Rosen, or "EPR") have proven false (google the Bell inequality and the Aspect experiment).

            More specifically, some of the particular variations in quantum mechanics that one would imagine could be useful for defeating a QKD system, such as nonlinearity, would give rise to highly unphysical effects (superluminal signaling), which we have not observed.

            It seems that quantum mechanics is an island in theory space [pitt.edu]--that is, any perturbation from the accepted theory seems to give something obviously unphysical, or at least something that does not agree with experiment.

            In other words, this is as close to proof as it gets in science. Clearly, quantum mechanics isn't the final word on, say, quantum gravity, but we're not going to be throwing out the undergrad quantum mechanics books any time soon.

            Yes, it would be nice to have information-theoretic security, but that doesn't seem to be possible for a key distribution protocol. Still, security predicated on the laws of physics is a hell of a lot better than security-based-upon-the-fact-that-we-haven't-heard -of-anyone-breaking-it, which is all RSA and other popular schemes have going for them (RSA isn't even computationally secure).

        • Re:"Unhackable Code"? (Score:5, Informative)

          by eddeye ( 85134 ) on Saturday April 30, 2005 @01:36AM (#12390651)
          Quantum Cryptography is indeed real cryptography. It uses the encryption system known as the One Time Pad.

          Not long ago, I took a graduate course in quantum computing from a researcher in the field. I wrote a paper for that class specifically on quantum cryptography. In 2001, I worked in the same lab as a physicist building a quantum cryptography device (we had lunch almost every day). I've also studied quite a bit of conventional cryptography. Trust me when I say this:

          Quantum cryptography has nothing to do with encryption, and barely anything to do with cryptography. It's an authentic channel with eavesdropping detection (but not prevention). In other words, QC is just a bootstrapping phase to distribute key material (random data) to two parties. Everything you do from that point forward, including everything involving your actual data, is classical crypto on classical channels.

          QC has nothing to do with one-time pads. You could use the key material for OTPs, if you're deranged. More likely you'll use something like CBC-AES, CTR-AES, CBC-3DES for encryption, which are much faster (less key material, not limited by QC data rate), simpler, and safer (unless you have the resources of a major world government to oversee proper handling of the data and key material at every point from creation to destruction). At any rate, you'll still need integrity even with a OTP or your data is worthless. That means SHA1-HMAC, CBC-MAC-AES, etc.

          Cryptography proper punts on the key distribution issue as it's not solvable mathematically. It's an administrative not an algorithmic problem, putting it outside the domain of modern cryptography. This applies equally to asymmetric crypto; public key databases and root certificates require proper oversight and maintenance. Hence the one problem QC solves, key distribution, is really external (but related) to the field of cryptography. That's why I say the two are orthogonal.

          The funny part is, QC isn't even a good solution to key distribution. Its physical requirements are costly, stringent, and limiting. Unless you're an ultra-cautious damn-the-expense client like the US govt, there are more cost effective ways to exchange keys, and much better ways to improve your data's security. QC is a problem in search of a solution.


          • QC has nothing to do with one-time pads. You could use the key material for OTPs, if you're deranged. More likely you'll use something like CBC-AES, CTR-AES, CBC-3DES for encryption, which are much faster (less key material, not limited by QC data rate), simpler, and safer (unless you have the resources of a major world government to oversee proper handling of the data and key material at every point from creation to destruction). At any rate, you'll still need integrity even with a OTP or your data is wor
          • The funny part is, QC isn't even a good solution to key distribution.

            Furthermore, to use QC for key distribution, you already need to have distributed a shared key beforehand! Search for "secret bit string is agreed to" or "a public, but authenticated, channel" in the QC wikipedia page [wikipedia.org] to see what I mean.

            Using QC to make an untamperable communication requires you to already have some other comm channel which is already trusted as untamperable- and if you had that, why not just send the keys on it in the
      • And when it comes down to it, the best form of extracting a password from someone is a gun held to the head of a loved one. I don't think you'd find many people who'd hesitate to give up a password in that situation.
    • "This is far from an "unhackable code". In fact, it's not even a code."

      Eh... sorta. The article talks about interception of the data not being terribly useful. I imagine they had to come up with some sort of code to make that work.

      Okay, it's a stretch, but technically they would need a form of code to make this work.
    • What? You didn't receive my password? BUT I JUST SENT IT!!!

      Not unhackable by a long shot, but you'd discover every hack. That is, until someone can perform a man-in-the-middle attack, assuming such a feat would be possible.

      • Re:"Unhackable Code"? (Score:2, Interesting)

        by crypto55 ( 864220 )
        No, it's not possible. The whole point about quantum cryptography is that the transmission method makes it physically impossible to crack data without the recipient knowing. There simply is no way to perform a "charlie" attack (charlie denoting a third user, after Alice and Bob). I've been doing research on this subject for the past two years, and met the daughter of the man (missed meeting him by an hour) who invented the principle behind the theory.
        • Not crack, intercept!

          If you nab the data from either end without the parties knowing, you could crack it without them knowing.

          What you can't do without alerting the others, is intercept the message in transmission.

        • Re:"Unhackable Code"? (Score:3, Interesting)

          by ebuck ( 585470 )
          Thank you. I'm grasping the impossibility of an eavesdropping attack, but how does this solution deal with other common communication problems, like:

          Denial of service.
          False positive intrusions.
          Reliability without retransmission.

          Is the idea to use wavelengths that are not readily absorbable by common atoms? If so, how would they theoretically be generated? Does the answer lie in the manufacture of "perfect" materials (assuming that such a material could exist)? How would impurities not eventually tunne
        • Yes, but from what I see of it, quantum cryptography only makes it impossible for the data (transmission) to be intercepted without the recepient knowing. Which means that in principle, the data might be intercepted anyway, it's just that the recepient gets to know of it.
        • Actually, it's usually 'eve' that's the middle "man".
    • Malicious people can do what the soviets did to spy on the western transmissions in Berlin, when they couldn't tap into optical. They tapped into the amplifier points.

    • Re:"Unhackable Code"? (Score:5, Informative)

      by Kainaw ( 676073 ) on Friday April 29, 2005 @10:46PM (#12390043) Homepage Journal
      Please stop thinking that "quantum cryptography" is a form of cryptography.

      That depends completely on how it is used. If I simply send a message in 1s and 0s over the photon stream, it isn't encrypted. I can only be certain that it either got there or it didn't get there.

      Cryptography comes in when you encode a message using a photon stream. The mechanics of doing this are old hat by now. It is done in the following steps:
      1. Send a stream of, say, 2,000 random 1s and 0s to the other end.
      2. The other end pics, at random, 500 of the 1s and 0s and sends a plain message back saying only which are chosen - the index, not the value. So, you can both form a 500 bit key (the number of bits is to your choosing)
      3. Encrypt the message using the key you just worked up and send it.


      This is commonly said to be 'mostly secure' because it is vulnerable to a man-in-the-middle attack. However, it is tamper-proof once it begins. If anyone attempts to read any of the photons as they travel down the stream, they alter the photons. So, you get a scrambled message at the other end and the hack is immediately known.

      Because it cannot be copied enroute without giving away that it is being copied, it is commonly called unhackable. You cannot make a copy of it and send it along while you try and hack it. I know, you are thinking you can just copy the photons and resend new ones with the same message. Nope - you have to know the spin orientation of the photons BEFORE you can read them for a 1 or a 0. If you read it with the wrong spin orientation, you will force it to the orientation you read it as and get an errant 1 or 0 that you incorrectly send down the line. So, you could say it is doubly-encrypted and doubly-protected from in-line hacking.

      • What about routers? (Score:4, Interesting)

        by BobPaul ( 710574 ) * on Friday April 29, 2005 @11:24PM (#12390220) Journal
        The problem I have with this is that it really doesn't have any place in the internet at large. Sure, it's great for point to point direct connections--ie, my secure installation has a direct diamond-fibre connection to your secure installation, but it really doesn't do much for more public transfers, like internet banking.

        This will secure transmissions between banks and internally at banks, but a secure system is only as secure as it's weakest link, and this doesn't improve security on the internet.

        Since the internet uses routers, switches, and hubs someone could always gain access to the router or pickup the broadcast from a hub through some other means and cause that system to log packets or duplicate them elsewhere, etc.

        Or is there a way to incorporate this into a system similar to the internet as we know it and make my home connection to my bank/paypal/yahoo shopping more secure?
        • Or is there a way to incorporate this into a system similar to the internet as we know it and make my home connection to my bank/paypal/yahoo shopping more secure? no there isn't, all QC does is provide YASPTP (Yet Another Secure Point To Point) transmission scheme, spending lots of money to do what OTP or even most PSK sytems can do today, but more leet and more expensive with a .0000001% improvement in number of global extintions it will take to crack
    • Quantum cryptography most definitely is a form of cryptography. But this article has nothing to do with quantum cryptography.
    • You don't get funding grants by claiming your project outcome will be mediocre.

  • Yeah? (Score:4, Insightful)

    by Eyeball97 ( 816684 ) on Friday April 29, 2005 @10:30PM (#12389946)
    I'm sure I'm not the only one who immediately thought "Titanic" when I saw the headline...

    • Re:Yeah? (Score:2, Funny)

      by Stevyn ( 691306 )
      um...I think you were.

      I was thinking about a hundred slashdotters screaming nothing is unhackable.

  • Wow! (Score:3, Funny)

    by computerme ( 655703 ) on Friday April 29, 2005 @10:31PM (#12389950)
    So its really is true:

    Diamond (encryptions) are forever!!

    Buh wump dump.

    (thanks. I will be here all week.)

  • Transmission speed? (Score:2, Insightful)

    by mschaffer ( 97223 ) *
    Transmission speeds are currently slow - 120km/h, but are expected to speed up

    Don't the photons travel at the speed of light in the fiber? Perhaps it is some other unit?

    • Re:Transmission speed? (Score:2, Informative)

      by Anonymous Coward
      The speed of light depends on what material/gas the light is traveling through.
    • Light travels 3*10^8 m/s in a vaccum. Light has a thing called index of refraction, in a vacuum n=1, in water it is 1.333 and in diamond n = 2.419 (diamond is known to have one of the highest indexes, actually the highest index of common materials). Because n is so high, the velocity of light through diamond is literally 2.419 times slower then in a vacuum (the actual velocity in this case doesn't matter, but you can probably figure it out in your head). Now you're thinking, well damn that is really fast st

  • Ummmm.... (Score:3)

    by ebuck ( 585470 ) on Friday April 29, 2005 @10:34PM (#12389970)
    Wouldn't the transmission speed have to be C? I mean, C isn't constant across all mediums, but even in quartz and ruby it's significanly faster than 120km/h.

    • Re:Ummmm.... (Score:3, Interesting)

      by Anonymous Coward
      Wouldn't the transmission speed have to be C?

      Many people don't realize that C is the speed at which an electromagnetic wave propagates, not necessarily the charge carriers themselves. The electrons in a copper wire, for instance, move pretty slowly, on the order of several seconds per millimeter.

      I didn't realize that drift velocity applies to photons in a medium, but it sounds like it may.
      • Yes, the electron pressure wave moves at almost C (mabye exactly C?), but that's not what what we are talking about here.

        In this case, yes, we are talking about light. So, it would follow that photons move at the speed of light. It would be kind of impossible for them to not move at the speed of light (yes, humor for the physics / philosophy minded).

        As an aside, with the advent of AC electricity, it's the oscillation of electrons that gets probagated through the line, and half of that oscillation is the
        • "In this case, yes, we are talking about light. So, it would follow that photons move at the speed of light. It would be kind of impossible for them to not move at the speed of light"

          Yeah, but what most people (I'm not saying you specifically don't know this) seem to miss is that light travels at different speeds. Usually, when someone refers to "the speed of light" as some sort of constant, the really mean "the speed of light in a vacuum", which is a speed very rarely actually attained by light, since ev
          • Ruby, Saphire, or maybe Quartz was the slowest material that was listed in my physics text (if I remember correctly). I guess I had to do one too many index of refaction problems in school.

            I remember reading about Cerenkov Radiation back in school. Facinating stuff, but again, only possible when NOT in a vacuum. Google to the rescue, look at this readable description of Cerenkov Radiation [physlink.com] if you are so inclined.

    • Re:Ummmm.... (Score:2, Funny)

      by linguae ( 763922 )
      Wouldn't the transmission speed have to be C? I mean, C isn't constant across all mediums, but even in quartz and ruby it's significanly faster than 120km/h.

      I've always heard that certain languages were faster than others, but I didn't know that the speeds of languages can be measured in kilometers an hour? C must be pretty fast then.

  • Curious (Score:5, Insightful)

    by Anonymous Coward on Friday April 29, 2005 @10:34PM (#12389971)
    I'm left wondering how it is they've managed to slow down the transmission of a photon to 120 kilometers in one hour, presumably in the glass fiber. Usually slowing down light that much takes a great deal of infrastructure and effort, it's rarely a side-effect.

    Slashdot and the www.news.com.au couldn't have both made the same screamingly stupid mistake and meant 120 kilobits per hour, right? Right?

    • Re:Curious (Score:5, Funny)

      by Anonymous Luddite ( 808273 ) on Friday April 29, 2005 @11:00PM (#12390113)
      >> Usually slowing down light that much takes a great deal of infrastructure and effort, it's rarely a side-effect.

      I think they did it by forming the photons into committees. They spend more time forming action plans and holding meetings than actually moving. Some of them actually go backwards...

    • Re:Curious (Score:5, Funny)

      by tomRakewell ( 412572 ) on Saturday April 30, 2005 @12:04AM (#12390376)
      Stop nitpicking about units! I have it on good authority that the author of this story made the Kessel Run in less than 12 parsecs, so he is a quite an expert on these matters.

  • Question (Score:5, Insightful)

    by Mark_in_Brazil ( 537925 ) on Friday April 29, 2005 @10:35PM (#12389980)
    OK, I RTFA, and there's something I don't get.
    TFA says
    But if the light was a single photon beam, others in the room could not see it, and the two friends would also know instantly if it had been intercepted.
    How? What keeps a third party between the two friends from receiving the photons transmitted by one friend and retransmitting exactly the same sequence of photons to the other while keeping a record, and therefore, a copy of the message?
    I'm pretty sure there's more to it than appeared in TFA, and that there is a way to be sure there isn't an eavesdropper between the two friends, but I don't know what it is.

    • Re:Question (Score:4, Informative)

      by The Mighty One ( 877644 ) on Friday April 29, 2005 @10:38PM (#12390003)
      http://en.wikipedia.org/wiki/Quantum_cryptography [wikipedia.org] Quantum cryptography is an approach to securing communications based on certain phenomena of quantum physics. Unlike traditional cryptography, which employs various mathematical techniques to restrict eavesdroppers from learning the contents of encrypted messages, quantum cryptography is focused on the physics of information. The process of sending and storing information is always carried out by physical means, for example photons in optical fibres or electrons in electric current. Eavesdropping can be viewed as measurements on a physical object---in this case the carrier of the information. What the eavesdropper can measure, and how, depends exclusively on the laws of physics. 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 disturb it and so leave traces.

      • Re:Question (Score:3, Interesting)

        by Jerf ( 17166 )
        The moral of the story is "Don't try to use your macroscopic-world intuition to understand quantum phenomena."

        It's so wrong, it's not even reliably wrong, like [people who oppose you politically]; you almost don't need to know what's right, just wait for [those idiots] to spout off and do the opposite. Unlike that, your real world intuition is so wrong it's not even on the same playing field, not a matter of "true vs. false" but "true vs. blue speckled porcupines."

        In conclusion, the answer is "a bathtub f
    • well because of the wierdness of quantum mechanics. The moment the photon was observed, it would change it's state and since the two friends knew what it was "supposed" to be they could tell someone else had "looked" at it...

      Yes I know odd but (I think in this case) true..

  • Where's the security? (Score:2, Informative)

    by shanen ( 462549 )
    The original fibre taps just spliced into the fibre and repeated the signals. It's only the later technology that could try to interpret the leakage. I don't see how this adds any security, except perhaps insofar as the time to make the more difficult splice will increase the odds of noticing the interruption. "Unhackable"? Nope. The race will never end.

    • Re:Where's the security? (Score:2, Informative)

      by MeanMF ( 631837 ) *
      Adding a repeater in the middle would add latency which could be easily detected by either end by running a few simple tests. Since this is a point-to-point technology your transmission speeds should be predictable and constant.
      • Assuming this is to be used for quantum cryptography (the original article is terribly badly written and this isn't clear), latency has absolutely nothing to do with it. A man-in-the-middle attack simply won't work due to quantum mechanics.
        • Assuming this is to be used for quantum cryptography (the original article is terribly badly written and this isn't clear), latency has absolutely nothing to do with it. A man-in-the-middle attack simply won't work due to quantum mechanics.

          I'm no physicist, but I think this is different.. It's closer to current fiber transmission technology, but instead of sending a burst of photons for a short, fixed duration you only send a single one.

  • Unusable (Score:2, Interesting)

    by Misroi ( 834266 ) *
    Right now it's downright unusable, think the kind of fiber optic you would need so 1 photon can be recieved at the other end? perfectly straight..!
    120km/h, just imagine the ping!!

    That technology could be "secure" assuming there is a direct link, that means no routing at all. If there is any routing involved then you just killed the concept. There is always the chance that someone will just cut the cable and "snif" it.

    Not a bad idea but right now it's far from promising...

    I'll stick with my encryption...

  • Anyone.. (Score:5, Funny)

    by Turn-X Alphonse ( 789240 ) on Friday April 29, 2005 @10:38PM (#12389999) Journal
    Anyone want a game of quake? We could have like 1000 pings. It'll be like old times again!
  • Eeeeh? Since when are data transmission speeds measured in kilometers per hour?

    I mean, if they managed to slow light down to 120km/h i'm damn impressed and I think a nobel prize would be in order for these people.....

  • misleading (Score:5, Insightful)

    by delirium of disorder ( 701392 ) on Friday April 29, 2005 @10:45PM (#12390040) Homepage Journal
    Not only is quantum cryptography not not a code or traditional cryptographic system, it is not exactly a perfectly "secure transmission medium" as some /.ers have suggested. It is a method of interception detection. It is a HARDWARE system that uses entanglement or the Heisenberg uncertainty principle to send photons in such a way that the communication system itself can always detect eavesdropping (and logically would cease transmission if interception is detected). It is not untapable....but any taping would do little good since it would be noticed.
    • I got a gut feeling there is an indirect effect of the photons that can be detected. Like other "unbreakable" systems this one will only last until it is cracked and the existence of the crack is discovered.

    • Yes and no. (Score:5, Informative)

      by rjh ( 40933 ) <rjh@sixdemonbag.org> on Friday April 29, 2005 @11:18PM (#12390194)
      Yes and no. Quantum key exchange is, as you point out, a key negotiation protocol which relies on the laws of physics to keep the negotiated key safe from eavesdroppers. However, there's absolutely no limit on the size of key you can generate. If you need a million bits of key, then fine: make a million bit key.

      Once you have as many bits of key as you have bits of data, you can treat it as a one-time pad. And that would be a perfectly secure transmission, as long as both sides make sure they destroy the key once it's been used to do an encryption or decryption operation.

      In other words, QKE leads quite directly to (a) a cipher and (b) a traditional cryptographic system.

      IAAGSSTS (I Am A Grad Student Studying This Shit).

  • Slower! Slower! (Score:5, Interesting)

    by Helpadingoatemybaby ( 629248 ) on Friday April 29, 2005 @10:46PM (#12390045)
    120 km/hr!?

    I hope they don't speed the connection up, I hope they're able to slow it down! Think ultimate storage medium, the only limit being the number of photons you can put in the length of a pipe.

    Running out of storage space? Hello sweet superposition! Yeah, my iPod stores 4.02 * 10^18 songs, but have to listen to them all in order.

    • sounds just like the Mercury delay line memory [maxmon.com] from the old days. Where they used sound pulses travelling in the mercury to represent presence or abscence of bits...
  • Is it just me or it would seem that the reporter got something wrong in the story. I thought the only way to get a speed of light in the area of 120 km/h was through very cold temperature and Bose-Einstein condensate. Perhaps they meant the transmission if limited to 120 kbps or something?
    • Since the propagation speed of photons in fibre is on the order of 300km/s (note I am not saying it is 300 km/s, I am saying that I believe it is better than 100km/s) it seems that either 120km/h is an unidentified bitrate, or a misentered item perhaps referencing 120kb/h, or even 120kb/s, 120kb/h would become 33 and 1/3rd bits per second, which even I consider an unreasonably slow data rate.

      Then again, I didn't read the article either, so perhaps it was transfered to the summary incorrectly...

      ~Rusty

  • 120 km/h (Score:3, Funny)

    by kabz ( 770151 ) on Friday April 29, 2005 @11:15PM (#12390182) Homepage Journal
    Transmission speeds are currently slow - 120km/h, but are expected to speed up.


    So these are Canadian electrons, eh ?

  • let me get this straight (Score:3, Insightful)

    by layer3switch ( 783864 ) on Friday April 29, 2005 @11:19PM (#12390196)
    120 km/h to send single photon in order to establish a secure channel?

    Hmm.. let me get this straight. So if I burn a DVD and send it to California from New York using FedEx 2Day service for $14.59, could I name this post as "Unhackable Transmission Medium for only $14.59"?

  • So... (Score:2, Funny)

    by licklame ( 880166 )
    I really don't think this tech is going anywhere.
  • Even if you can't listen in, you can receive and retransmit.

  • its not foolproof (Score:2, Interesting)

    by AndreySeven ( 840823 )
    I am no expert in the field of quantum cryptography, but i could imagine a sort of situation where the "man in the middle" captures all of the photons, before they are sent to the receiver, then calculates the required speed to make up for the latency and boosts the "signal" to prevent the reciever from knowing anything has gone wrong. Of course, I could be totally wrong...

  • Unhackable... Unnecessary! (Score:5, Funny)

    by WaR.KiN ( 805785 ) on Friday April 29, 2005 @11:42PM (#12390288)
    It's not that the code is unhackable, it's just that hackers won't be hacking into your bank account anymore. They'll just take the diamonds.
  • "to Create Unhackable Code"

    I'll stop reading right about there.

  • 120 km/h? (Score:3, Interesting)

    by nrlightfoot ( 607666 ) on Friday April 29, 2005 @11:51PM (#12390334) Homepage
    That has to be a typo. Even in diamond the speed of light is only a little about 2.5 times slower than in a vaccum. I'm very interested if the light is going 120 km/h in the optical cable though, because that would make it possible to theoretically build a time machine by winding the cable in a cylinder, but only if it retained that speed with more light in the cable. There is also the caveat that the metric this was solved for involved an infinitely long cylinder of rotating light, so it may not apply to finite cylinders.

  • This unhackable/ya right (Score:3, Funny)

    by dilvish_the_damned ( 167205 ) on Saturday April 30, 2005 @04:51AM (#12391157) Journal
    I had this largish thing describing what I thought of this relativly cool technology and my reticence in buying into it as the "Next Big Thing(tm)" but I think I can sum it up like this:

    "All your diamond are belong to us" -- lopht

  • I've already diagramed a system of unhackable code (Score:3, Funny)

    by Jekler ( 626699 ) on Saturday April 30, 2005 @07:23AM (#12391504)
    It just relies on a perpetual motion device to power the division by zero generator.

  • Good challenger for most misleadinfg SD article. (Score:3, Informative)

    by Ancient_Hacker ( 751168 ) on Saturday April 30, 2005 @09:57AM (#12391856)
    • A quantum channel is only good for as far as one photon is likely to survive above the noise level-- maybe a kilometer at most?
    • Anything farther than that will involve detecting the photon and relaying it-- a chancy proposition which adds waay too much noise and of course one can intercept the signal at the repeater.
    • Exactly how long can you make a diamond cable? Splices are very unreliable and lossy.
    • What is that 120 km number doing in there? Mighty unlikely.

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