> The Signal Protocol is probably the most secure ever created for messaging.

The LavaBit founder thought the same. The most secure email service ever created with famous users like E. Snowden.

https://lavabit.com/ ( Read )

Threema user here.
ProtonMail user too.

Both based in switzerland with zero LEA / CIA / FBI / NSA attacks against the developers.

https://threema.ch/en/
https://protonmail.com/

Signal is USA therefore security don't exist.