https://medium.com/@wireapp/axolotl-and-proteus-788519b186a7
more thought and whether one should avoid Signal and work with a more friendly project that doesn't seemingly fail at its desire to have widespread use of the protocol and actually tried to sue WireApp? WireApp's now approved as a non-infringing implementation in Rust, so that's great for reliability.
Edit: The suing part was initiated by Wire as a response to Moxie demanding GPL compliance over their claim Wire is infringing. I got that backwards.