Small Leap for Photons, Giant Leap for Encryption

Loraine Lawson

If you're at all familiar with encryption keys, you know that they're a great security measure -- but not an unbreakable one. While they can be so long as to seem unbreakable, they're static and based on complex algorithms. Thus, given the right resources, they can be deciphered.


So, for some time now, the Golden Snitch of Security -- if you'll allow the Harry Potter reference -- has been quantum encryption. As this article in Technology Review explains, quantum encryption relies on two "entangled" photons. Measuring one changes the other in the same way, so, in effect, if you agree on which polarization represents a zero and which represents a one, you can build yourself a code. And it can only be deciphered with one of the two photons.


That's got to be the coolest encryption method since the Little Orphan Annie Decoder ring -- which, by the way, didn't exist until 2000.


Quantum encryption works. The only problem has been getting it to work over long distances and through the atmosphere. Otherwise, all you can do with it is send an excessively secure message to your lab buddy telling him to "Drink more Ovaltine." (Another fib from A Christmas Story -- according to the Radio Orphan Annie Secret Society, Annie's secret message never promoted Ovaltine.)


But now, scientists have managed to use quantum encryption across islands, a distance of 144 kilometers -- and that's a world record. To give you an idea, most satellites are hovering at 300-500 kilometers. So, we're now nearly half the way to being able to use quantum encryption via satellite.


The two-page article goes into fun detail about how scientists managed to produce entangled photons that would maintain their entanglement despite the distance. I highly recommend it, but then again, I've always wanted to be a member of a covert operation, such as the FBI or maybe Little Orphan Annie's Secret Society. Neither of them have invited me yet... as far as you know.

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Jun 12, 2007 11:56 AM Ed Ed  says:
Another cool facet of quantum encryption that supports its claim to un-hackability, though I never like to say never when it comes to codes, is the fact that an external observer scanning the message can render it unreadable. I think it has to do with Heisenberg's uncertainty principle or something. [Left my propeller beanie at home.] In other words, Alice sends Bob a quantum-encrypted message. Clarissa is sniffing for such a message and intercepts the signal. Since she observes the signal and tries to decipher it, the signal itself changes, rendering it unreadable to both Clarissa, Bob, and Alice. Bob and Alice will never meet at Starbucks for a latte, but neither will Clarissa. Reply

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