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Originally published at Internet.comBy John Savard for SecurityPortal
Dr. Michael Rabin, currently at Harvard, announced a new kind of cipher that is "provably unbreakable." And, indeed, it is exactly that, given the assumptions on which it is based.
Two people wishing to exchange a secret message would need to set up a source of genuinely random numbers that broadcasts these numbers to both of them, and that produces so many random numbers that no eavesdropper could possibly record everything it broadcasts for whatever interval of time it takes to set up a message.
The first step in sending a message would be for the sender to notify the receiver to start listening for random numbers at a certain time, or both parties might be continuously listening, so that the numbers to be used might be collected over days or weeks instead of minutes. Both parties would, according to a prearranged system governed by a key, listen for, and record, a minute subset of the broadcast random numbers, small enough that it could be recorded easily.
Then, the sender would use those recorded numbers to encipher the message, and the receiver would use them to decipher it.
An eavesdropper, trying to determine the key of the prearranged system used to pick the random numbers used to encipher the message, would need to be able to refer to all the broadcast random numbers, because the eavesdropper wouldn't know which ones were the right ones until after he had actually broken the code...
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