How To Build a Quantum Eavesdropper 67
KentuckyFC writes "Quantum encryption is perfectly secure, in theory. In practice, however, there are loopholes. Now Japanese scientists have designed a quantum eavesdropper that exploits one of these loopholes to listen in to quantum conversations. QC's security arises from the impossibility of making a perfect copy of a quantum object without destroying it — so the sender and receiver can always tell if they've been overheard. But it turns out that an eavesdropper can make imperfect copies and use them to extract information from a quantum message without alerting sender or receiver (abstract). The Japanese design does just this. That should worry banks and government agencies that have begun to use some of the commercial quantum encryption systems now available."
Oh no. (Score:5, Funny)
Ziggy says there's a 98.5% chance that your security is flawed.
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You fool! (Score:5, Funny)
Not so hard (Score:3, Informative)
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Re:Not so hard (Score:4, Interesting)
If N is too low, you drive the error rate high enough that the communication is no longer regarded by the parties as secure.
N is always either too high, too low, or both.
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It seems copying quanta such that no change is dete
Long time lurker, first time poster (Score:1, Interesting)
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Better Candidate for the South Park Defense (Score:1)
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Ob. LOTR (Score:5, Funny)
Re:Ob. LOTR (Score:4, Funny)
Logical disconnect (Score:5, Insightful)
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What bothers you, is not that they say "theoretically impossible", its that such a term morphs into "completely impossible in all implementations" in the minds of the general public and gives them overblown expectations. That's not really the fault of the people who use the term,
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They aren't exploiting an implementation weakness. They're exploiting the fact that you don't have to do what's "theoretically impossible" to extract information from the message. Look at it this way: Somebody said:
1) You can't copy the quantum communication without visibly disturbing the original
2) ???
3) QC can't be broken!
But there was hand-waving at step 2, and it apparently isn't valid (if this technique turns out to be a practical exploit, which is yet to be seen).
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1) You're assuming that by "partial copy" they mean they only get some of the encoded information; that may be what they mean, but it isn't what they say.
2) What you're saying also implies that the message itself is sent via quantum crypto; this is not the typical case. QC is used to distribute keys. Is getting part of a key useful? I'd think so, as long as you know which part you have.
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For example: "it is impossible to write a program that can determine if another program will halt or not" is often reworded as "it is impossible to determine if a specific, given program will halt or not", which is patently untrue.
The theory in this case appears to be, if I understand correctly: "it is impossible to make a complete copy of a message without it being detected." So they just figured they can make a partial copy, thereby side-stepping detect
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10 rem this will never halt
20 goto 20
Or this one:
10 rem this will always halt
There are two interesting things here: first, I'd bet that for 99.9% of all programs in real life, it is not only possible to determine if
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I think it's not quite that easy or we would be able to catch almost all crashbugs automatically. We can catch some but the tricky ones don't get caught automatically.
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But if we assume they will build it, and if we assume it will work... Well, it doesn't do anything that's "theoretically impossible". What it violates isn't the theory -- what it violates is the glib assumptions of those who interpreted the theory to mean they could end what is probably an endless arms race.
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Theory (Score:2, Redundant)
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IANAP, but can someone please tell me how the theoretically impossible became theoretically possible? Did the theory change, or was the math wrong, or did His Great and Wonderful Noodliness screw with the results?
It is still theoretically impossible to get a perfect copy without alerting the sender and listener. However, this technique essentially reads the "noise" around the conversation and rebuilds the data from that. This is much like a damaged hard drive. While you cannot get the data directly, you can rebuild the data with the bits you do get.
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It's theoretically possible to produce a machine that implements perfect quantum security. The exploit above does not disprove the theory, only the implementation.
Oh, you want to know why the implementation was flawed?
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In theory, wormholes allow FTL communication.
Different theories.
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That sounds a lot simpler than it really is. The only way I can see to do it is to shoot entangled particles from point A to points B and C, and when someone at B tampers with it's particles, C sees the diffusion pattern disappear instantaneously (or even faster, if B is farther from A than C is.... which means communicating with the past
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If the real error rate is well below the communication error ceiling (where it stops working), then Charlie sitting in the middle can extract a few bits out of each packet.
OTOH, assuming this channel is used to exchange the 256-bit AES key to be used for the bulk communication, then the parties can simply set the acc
Banks using modern crypto? Hah! (Score:4, Interesting)
Granted, 3DES is actually not truly that bad in terms of its 112-bit effective security compared to AES-128 (though it's not the weak point when you use 80-bit effective RSA1024). However, just because ANSI X9 has started including modern technologies like ECC and AES or other technologies like quantum crypto are promising, you can bet that the banking industry will be one of the last groups to take up more modern crypto technology. Heck, even the NSA is mandating Suite B with ECC and AES by 2010 for government security! It's one of the few government agencies to actually act faster than the private sector.
Finally, I wonder if the original poster could show the relevant ANSI X9 aka banking security standard which calls out quantum crypto. I don't think I've seen one, and the banking industry typically lives and dies by X9.
not all banks. (Score:2)
like switzerland.
even government agencies have started testing quantum cryptography, to help secure the transmission of vote results.
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Even RC4 and DES can be secure when used correctly in situations where there isn't time to brute-force anything, and at least the insecurities and algorithms themselves are well understood, which isn't necessarily true for more modern algorithms. (I think this article is a good example of the latest buzz in crypto st
Multi-layered security (Score:1, Interesting)
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If the 'eavesdropper' can only make 'imperfect' copies then it seems to me using multiple levels of security would defeat the eavesdropper. For example private key encrypted data being tunneled over the quantum channel. Using this technique they would get a copy of imperfect encrypted data - which would be impossible to decrypt even if you had the private key .
Remember that, even in the ordinary case, the receiver does not receive a perfect transmission, which implies that there must be some tolerance for error. An encrypted data stream would require error correction so the receiver could decrypt it. Therefore, for your idea to work, the level of error correction available must be such that the receiver can recover from errors, but the distortion from the imperfect copies makes error recovery impossible for the eavesdropper.
As I did not read the paper, I do
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Oh, come on (Score:1, Funny)
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Please hit 'Reload' more often. Thank-you. (Score:2)
-FL
The obvious question is... (Score:2, Troll)
Just because you COULD get data out doesn't mean it is actually usefull to do so.
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Non universal quantum cloning has been less studied. In some cases it's obvious and trivial what the best implementation is (100% for cloning a photon in a known polarization state - just put a lightbulb behind a polarization filter at th
i gotta headache (Score:1)
tough abstract (Score:4, Interesting)
No need to worry about this (Score:5, Informative)
This is wrong. The eavesdropper gets imperfect copies and so does the receiver. If the quality of the receiver's copies are as bad as the eavesdropper's, any working quantum crypto setup will abort and not try to make a secret key out of it.
That should worry banks and government agencies that have begun to use some of the commercial quantum encryption systems now available.Nobody needs to worry about these kinds of attacks, as the software in all commercial quantum crypto systems automatically checks and takes care of these kinds of attacks. What the paper shows is how to implement in practice a class of attacks that has been known for years how to do in theory.
There are other attacks on quantum crypto systems that actually attack loopholes in the implementation, and some of these have previously been discussed on slashdot here [slashdot.org]
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Believe it or not, this is actually done in some commercial systems. The rationale is not that it is necessary more secure, but that there are certification standards for conventional cryptography and the quantum crypto devices can then be certified.
old news (Score:1)
Vapourware: ID Quantique (Score:2)
"id Quantique is the leader in the development of advanced encryption solutions based on classical and quantum cryptograhy."
cryptograhy?
Oooh, maybe they're trying to hide themselves through dodgy spelling! Cunning!
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