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Quantum key distribution is regularly touted as the encryption of the future. While the keys are exchanged on an insecure channel, the laws of physics provide a guarantee that two parties can exchange a secret key without knowing whether they're being overheard. This unencrypted-but-secure form of key exchange circumvents one of the potential shortcomings of some forms of public key systems.
However, quantum key distribution (QKD) has one big downside: the two parties need to have a direct link to each other. So, for instance, banks in and around Geneva use dedicated fiber links to perform QKD, but they can only do this because the link distance is less than 100 km. These fixed and short links are an expensive solution. A more flexible solution is required if QKD is going to be used for more general encryption purposes.
A group of Italian researchers have demonstrated the possibility of QKD via a satellite, which in principle (but not in practice) means that any two parties with a view of a satellite can exchange keys.
(Score: 3, Insightful) by draconx on Tuesday August 25 2015, @09:30PM
It doesn't need to be impossible. The odds of successfully eavesdropping only need to be worse than randomly guessing the key by flipping coins, which is also not impossible (just unlikely). If we can achieve that, then we can conclude the key exchange is secure against eavesdroppers because flipping coins gives better results.
(Score: 1, Insightful) by Anonymous Coward on Wednesday August 26 2015, @12:40AM
The point of QKD isn't that interception is impossible: it's that undetected interception is impossible. Collecting information (eavesdropping) on the system changes the system, which means that eavesdropping cannot go unnoticed. When you notice interception, you halt the negotiation of the shared secret for the encrypted session. If you don't notice interception, then your shared secret was negotiated safely.
This is incredibly expensive, cutting edge research. Meanwhile the NSA has already side-channeled the client boxen and has simply been keylogging the shit out of Alice and Bob, so they know everything without dicking around with your magic photons, which were always just a distraction.