I'm surprised more people haven't read between the lines: the NSA is in possession of quantum computers and interference based decryption is probably already in standard use. Insiders also have dropped hints the Tor networks is, in fact, a trojan horse. We basically have two * extreme * options: 1) a trusted courier with a sealed envelope (don't underestimate this Game of Thrones like scenario as the US Military defeated itself in the largest wargame in the gulf by using courier, sealed envelopes, and motorbikes) and 2) quantum cryptographic communication. The latter is still only the realm of university labs and down at LANL but I read a paper which stated it's physically possible to pass keys along ethernet cable, but all parties need a device which acts as a gate. This in turn opens up Alice and Bob to traditional decryption methods if they're not air gapped from the web.