Re:Chinese scientists test quantum entanglement over unprece...
by kbenson on Friday June 16, 2017 @12:32PM
(#14570347)
It sounds like an interesting, if very expensive, way to get around primes for key exchange, in the world where prime factorization is much more efficient. Need a random number, look a bun of shared digits in a predefined order. You now have a shared random number that's perfectly secure, as long as you shipped out your shared state in advance.
I give you a magic piece of paper with a two binary digits (00/01/10/11) on it. I also keep such a paper for myself. If we both start by looking at our first digits then those will mysteriosly match, but if we then look at our second digits they will have just a 50% chance of matching. However, if we both start by looking at the last digits, then those will match, and our first digits will have a 50% chance of matching. If you and I start by looking at different digits, then the digits we read are just standard random bits.
The cool thing about this is that our magic paper will also work instantly even if we are lightyears apart. However, if you decide to look at the last digit and you see a 1, then that tells you nothing about me or which digits (if any) I have looked at, so I can't send you a message with this paper.