I just leanred about another secure chat app.

https://briarproject.org/how-it-works/

From the manual..

"What is Briar?

"Briar is a messaging app designed for activists, journalists,
and anyone else who needs a safe, easy and robust way to
communicate. Unlike traditional messaging apps, Briar doesn't
rely on a central server - messages are synchronized directly
between the users' devices. If the internet's down, Briar can
sync via Bluetooth or Wi-Fi, keeping the information flowing in
a crisis. If the internet's up, Briar can sync via the Tor
network, protecting users and their relationships from
surveillance.

It cooperated nicely on my Android-capable Blackberry. I seems
to operate much like Session, very discreet, and user-
controlled. But unlike Session's putrid neon green for chat
bubbles, Briar is easier on the eyes!

It has a built-in "blog" that can be used to broadcast a
message to all known "Contacts".

--- OpenXP 5.0.51
* Origin: Ogg's Dovenet Point (723:320/1.9)
� Synchronet � CAPCITY2 * capcity2.synchro.net * Telnet/SSH:2022/Rlogin/HTTP