So Decent is pretty fucking amazing!
Check it out on: http://gwenbell.com
(An in-browser social network based on Scuttlebot and Minbase with seamless on-boarding. Seriously easier to get started with than a centralised social network like Facebook. Very, very impressed!)
PS. I’m @aral on there.
It seems the SSB stack will secure your private messages client-side, and the Merkle tree ensures your public messages aren't tampered with in-flight, so there's that. Eve with WireShark can presumably still read the public messages you're writing/reading, and your private messages' ciphertext.
See http://decent.gwenbell.com/#%kqRNdQ9uSAr+DpB/J9a5shF/5P/yOvsWOM1bfMU3vQQ=.sha256 which recommends running Decent server locally & reverse-proxying. Much like Mastodon Fediverse, but with SSB.