My 2-cents. I think no crypts are not unbreakable. Yes, I agree with @steevc that it's about how long you need it for. Was NSA the one who invented SHA256? And I read that btc = SHA256^2 Is it something to lessen worries on encryption safety due to ^2... or is it stressful since it's by NSA? I don't know which or how to decide.
China claims:
...an uncrackable communications system, by turning messages quantum and taking them into space... Additionally, the complexity of quantum mechanics makes it virtually impossible to reverse engineer the quantum key generated through quantum entanglement.
They are referring to their communication systems being "spy-proof". Any thoughts on this?