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?
Running a SimpleX chat SMP server now, anyone is welcome to use it and the architecture of the network means that I'll have no visibility into messages or who talks to who using it.
Address: smp://HWK6x65IcNpRyGDQUtOMSSofcQv2D72-NbEmqg-SwAE=
@smp
.sethforprivacy.com
Or use QR below:
If you want to learn more about SimpleX, you can listen in to my latest Opt Out episode:
https://optoutpod.com/episodes/s3e02-simplexchat/
Really loving just about everything to do with SimpleX recently.
Discussion
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
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.