First Bank Transfer via Quantum Cryptography 310
An anonymous reader writes with today's announcement that "the Austrian project for Quantum Cryptography made the world's first Bank Transfer via Quantum Cryptography Based on Entangled Photons; see also Einstein-Podolski-Rosen Paradoxon." (For more background, see the recent Slashdot post "Quantum Cryptography Leaving the Lab.")
Quantum Crypto Provably Flawed? (Score:5, Interesting)
Is quantum crypto provably flawed?
I've seen tons of blurbs stating the the link is "absolutely" secure, but it seems that isn't really the case. [dhushara.com] (see the bottom of the page.)
What strikes me about all this is the following section:
"each pulse should be attenuated to an average of about
What that says to me is that there is not way to 100% know you're transmitting just one photon.
It sounds like there's no device that is capable of transmitting one and only one photon with 100% reliability. If this is the case, a lot of the arguments about how secure this is are vastly overstated.
In the end QC would be vulnerable to a man-in-the-middle attack by watching for multi-photon emissions.
If this is the case, a lot of the noise surrounding QC could turn out to be hype. (The big plus for quantum crypto is that it's supposedly immune to this.) Is there a quantum physicist in the house?
Re:Quantum Crypto Provably Flawed? (Score:5, Interesting)
If an eavesdropper successfully split the extra photons off, they have successfully captured 1% of the data stream. First off, that's not much data if you want to reconstruct something meaningful in the way of information carried by the stream.
Another problem, however, is the effect of the splitter on the rest of the stream. When a single photon passes the splitter, which path does it choose? If I'm not mistaken, that choice will be at random. If so, then the presence of the splitter becomes immediately detectable because half the single photon pulses never reach their destination. In fact, the number missing is likely to be so close to 50% that the presence of the splitter should be obvious to the bank.
How Immediate is Immediate? (Score:3, Interesting)
Is this instantaneous? Wouldn't that violate the whole speed-o-light thing?
is this as big as I think? (Score:3, Interesting)
To me this story is rather sensational -- I didn't realize that quantum crypto is that close to actually being used; it also seems to me that wide use of quantum crypto is going to revolutionalize the field.
Can someone who knows a lot about this explain to the rest of us: is this "WOW!!!" or just "neat!"?
Re:How does it defeat repeaters? (Score:1, Interesting)
Re:But... (Score:5, Interesting)
-- standard explanation for weird quantum things when you don't know the right answer.
I was just reading about that last night in The Elegant Universe.
For those who haven't heard of it before, here's the experiment:
- take a wall with light shining on it from a projector.
- place a board in-between the wall and the projector that interrupts the beam of light. The board should have two vertical slits cut in it, which can be opened and closed independently of each other.
If you open just the left one, you get a vertical bar of light on the wall.
If you open just the right one, you also get a vertical bar of light on the wall, offset from the one that was there with the left one open.
Now, intuitively you would think that if you opened both at once, you would just get two vertical bars of light, but you don't. Wave interference means you get a whole bunch of light and dark vertical bars on the wall.
Here's the spooky quantum-mechanical part - the same interference effect happens even if the projector is designed to only emit one photon at a time, then wait until it has hit the wall (or the board) before sending another. You will still get the bands of dark and light.
Pretty weird, eh?
Re:snake oil (Score:2, Interesting)
Entanglement (Score:3, Interesting)
Re:But... (Score:3, Interesting)
|>oug
Hype (Score:4, Interesting)
Furthermore, this is really just a Quantum Key exchange. So tack on whatever protocol you wish to use once you have the key. Quantum encryption is something that would require quantum computing first.
Also please note, the quantum transmission is not even "secure." Its just that if anyone but you reads it, you are secure in the knowledge that you will know about it.
At least this is what I have understood. Still hype. Notwithstanding, as science this is probably an advancement. Its just not what its being marketed as.
What about mandated wiretap access? (Score:1, Interesting)
theory and SF are 'entangled' too, it seems (Score:3, Interesting)
This is not impossible, because, contrary to what most ppl think, lightspeed is in fact an average; within one beam, there can be photons that are moving slightly slower, and photons that move slightly faster then the speed of light.
This, however, leads to the conclusion that those particular photons come from - at least potentially - another time or space. So, the film 'paycheck' might not be complete bullocks after all (though it's doubtfull we are ever going to be able to create a usefull 'time-viewing' tool out of it).
Then again, never say never, as Bill Gates with his '640K is enough for everyone' can vow.
The theory about another 'space', in contrast, leads us to the possibility that those photons actually come from parallell universes. It seems SF, but it are, in effect, valid scientific hypotheses which deserve further investigation.
After all, apart from these theories, there *is* no explication for the result of that experiment.
Re:Proof of Concept (Score:3, Interesting)
Very good point. FWIW, I actually thought of this (really
But I also think I raised a valid point. One cannot do everything -- or at least everything well. Choices have to be made. Investment in quantum crptography may be a good choice, and perhaps a better one than investing in more training, education, etc. re: social attacks. However, I still suspect that one (not the only, perhaps not the most important, but one) reason for the investment in QC is that it is interesting. Spending money on paper shreders and training employees to use them, etc., is less than fascinating.
Re:theory and SF are 'entangled' too, it seems (Score:3, Interesting)
That photons can be slowed down is not even disputed anymore, there have been numerous examples of it in various degrees (depending on the medium it passes through). I even believe there was a slashdot-article about it, when some researchers managed to slow it down to a crawl.
For faster then light photons (obviously, only possible with non-mass quantummechanical particles) there is more discusion about it, since it's extremely difficult to prove. However, this experiment actually *would* be a possible contestant in proving the hypothesis.
One more link (Score:3, Interesting)
"The entangled photon pairs created by Kwiat's team are produced using two thin, nonlinear optical crystals to split the "parent" photons from a laser into entangled "daughter" photons. In previous research at Los Alamos, these entangled photons have been used for quantum cryptography to create unbreakable cryptographic keys that can be used to lock or unlock encrypted messages.
Decoherence is a problem in quantum systems because the fragile quantum superpositions of entangled states are destroyed by unwanted coupling to the environment through which the photons are passing. Decoherence in Kwiat's system is intentionally created by passing the entangled photons through a roughly 10 millimeter piece of quartz. This optical environment produces a collective decoherence in the photons where one particular entangled photon state is, as predicted by quantum theory, essentially decoherence-free. These photons could serve as the basis of information carriers for quantum communications."