Yeah talking about difficulty, then you will love this: https://www.science.org/content/article/china-s-quantum-satellite-achieves-spooky-action-record-distance

Yeah talking about difficulty, then you will love this: https://www.science.org/content/article/china-s-quantum-satellite-achieves-spooky-action-record-distance https://www.science.org/content/article/china-s-quantum-sate... If we really wanna be security, then entailment is a good bet. I could imagine essential financial clearing, emergency infrastructure could use this level security. Don't know how feasible it is for consumer grade usage yet though.