Network-level encryption is via TLS, comms level encryption uses the same Double Ratchet approach that Signal uses.
Lots more with threat models broken down here:
https://github.com/simplex-chat/simplexmq/blob/stable/protocol/overview-tjr.md
First time looking into this. The protocol doesn't seem to mention how the encryption is done ( https://github.com/simplex-chat/simplex-chat/blob/stable/docs/protocol/simplex-chat.md ). Also let's assume all data is encrypted - you will still have visibility into which IP address the connection came from & the timing, right?
Discussion
As mentioned in the pod network-level privacy isn't a core focus right now, but there is native Tor integration (via SOCKS5 proxy) in SimpleX that can be easily enabled if that is a concern.