Quantum Key Distribution (QKD) is based on physics rather than classic information theory. You get a quick, easily understood lesson on entangled photons, happy and sad photons that are truly random, not pseudo-random. The photons can be "random and correlated over a great distance". It's not just theory; it's being tested at SDG&E.
Duncan Earl discusses the theory of QKD, and then Adam Crain talks about how this can be used for key distribution in an ICS protocol, using SSP-21 as an example.
