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Ultrasecure Quantum Communications Over Thin Air
SlashDotIDOne writes "Well, given a hundred years at university and a few extra titles to my name, I'd be comfortable trying to summarize the article so don't take what I say at face value. Apparently British and German researchers have found a way to use quantum crypto through the air, thus allowing it to be used to communicate with satellites, etc. A very secure form since you know whether a message was intercepted, rather hard to tamper with ;). Courtesy India times and Google's new news service."
I had a student do a project on this. You can live with quite high levels of photon loss.
Essentially, the process runs:
send a large number of (more-or-less) single photon pulses, carrying random data
recipient reports over an open channel, which pulses they got and some more technical information.
From this, sender and recipient can work out the subset of the random data that they take into the next step.
Now they (openly) exchange some checksums and things to determine the rate of bits which appear to have changed in transit, either due to eavesdropping, or noise and to get a common bitstring. From this, they can work out how to combine the bits of the bitstring to get a shorter bitstring which (with high probability) no eavesdropper can guess any part of.
Finally, they use this common secret bitstring as a key for a one-time pad.
Simulations suggest that even 99.9% photon loss is not fatal.
Does anyone else think it would be a great addition to Slashdot's stories if they would include a link to the google news search under every headline? I don't think it would be that hard to automate, but it sure would open the door for us users to see a lot of different articles per issue discussed.
~ now you know
WMOB The recordings and transcripts (that you REALLY need) of some gangsters wiretapped by the FBI.
Its awesome!
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