You basically create a hash table over public identities (bucket = pubkey % n) with an n chosen such that you get a bunch of unrelated people in each bucket but not so many that peers are overwhelmed by the message load on their bucket. Messages can be as simple as ES-SS-DH (basically Noise_X), same properties as e.g. PGP, i.e. no forward secrecy, no KCI resistance.

(This is patented, or at least pending)