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Photons Can Still Torpedo Quantum Hackers


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Stand down, laser wielding hackers: quantum cryptography is not vulnerable to blinding laser attacks after all. At least, that's the view of a bunch of quantum mechanics at Toshiba's lab in Cambridge, UK, who say they have recreated a recently-discovered quantum hack and claim to have found a way to defeat it.

In quantum cryptography, the digital codes used to scramble secret documents, pictures and video - encryption keys - are are encoded in photons transmitted through an optical fibre. To ensure that no attacker intercepts the key during transmission, the polarisation angle of these photons is known. The security comes from the fact that, by the spooky laws of quantum mechanics, any attempt to intercept those photons changes this quantum property. So if the received polarisations are wrong, the receiver knows their channel has been compromised.

In the September edition of the journal Nature Photonics, however, a Norwegian/German cryptanalysts showed that if the photon detector commonly used in quantum cryptography is 'blinded' by a bright, pulsing laser beam, an eavesdropper can easily read off the secret keys being transmitted as voltages dropped across the resistor that sets the detector's operating voltage. And the receiver is none the wiser to the interception.

Not so, Toshiba now says in the December issue of the same journal. "We've shown that the detector blinding attack is completely ineffective, provided that the single photon detectors are operated correctly," says the firm in a statement issued today.

By removing the troublesome resistor and ensuring the single photon detector (which generates a vast "avalanche" of electrons on receipt of a photon) operates at the correct sensitivity level, the firm says the blinding flash attack simply cannot work.

To the uninitiated, this spat might sound a poor advert for the technology - but it is in fact a sign of vigorous health in the field. All cryptographic routines that are worth their salt go through a process of attack and fix - ultimately ensuring it's as secure as possible. The RSA and AES encryption algorithms that protect our banking data, for instance, have been through such hoops. In crypto, it's a case of no pain, no gain.

from http://www.newscientist.com/blogs/shortsharpscience/2010/12/photons-can-still-torpedo-quan.html?DCMP=OTC-rss&nsref=online-news

i copied the whole article bc theyre only available for a while

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What a coincident, I read something similar on Quantum Cryptography a while back. However I read an article, that stated that its virtually impossible to crack Quantum Cryptography, but on the other hand, the device used to encrypt the message, apparently has a flaw in it and with the right equipment you can intercept the keys, used to encrypt the message.

I see if I can find the article.

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i hope it never gets cracked lol

.... just on the basis i bet some pretty important stuff / data is stored / controlled this way ... you can see the scenario super power vs super power

very interesting how they do it tho

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i hope it never gets cracked lol

.... just on the basis i bet some pretty important stuff / data is stored / controlled this way ... you can see the scenario super power vs super power

very interesting how they do it tho

For the time being, not even the Chinese supercomputers can crack this key.

It would require massive amount of computational power, like a quantum computer for instance.

Its safe for now.

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