Re:Cambridge launches UK’s first quantum network
by OscarCunningham on Tuesday July 10, 2018 @06:05PM
(#17502621)
No, this kind of thing is ruled out by the protocol. There's a theorem called "monogamy of entanglement" which means that two maximally entangled qubits can't also be entangled (or even correlated) with a third. This means that Alice and Bob can guarantee that the key they're agreeing on wasn't intercepted. The theoretical argument is airtight. It doesn't rely on any assumptions about the adversary's computing power, or on whether the adversary has access to a quantum computer. The only way it fails is if physics works significantly differently to how we think it does.
Of course there can still be implementation errors or attacks at the endpoints. The strength of the chain is the strength of the weakest link. But the abstract protocol itself is a very strong link.
they are unhackable using classical methods. So the hacks would be QM based as well (so DefCon will be like QM physicists symposium). Like something along the lines of entangling with (yet not measuring) the signal and performing "shadow" ("counterfactual quantum communication") read of a that signal (entanglement transitivity/swapping, especially if the read/measurement is done after Alice&Bob had already got satisfied with the integrity of the signal as there are also interesting possibilities with that "entanglement in the future affecting the past". Or like this QM analog of NSA Google fiber splitter https://www.extremetech.com/extreme/156673-the-first-quantum... : the photon 4 would be injected back into the channel and Alice and Bob would never know the difference [between the pair 1,4 and the original pair 1,2] while the photon 3 would go into Eve's pocket ).