It's easy. We just generate our own key pairs, establish a web-of-trust by signing each others public keys at in-person meetups, and then use those signed keys to authenticate all the digital communication we do with each other.

You know, like we've been doing with our emails since PGP was developed in 1991. You can tell how simple the process is, by how ubiquitous it has become in a mere 30 years!