Signal is not the place for top secret communications, but it might be the right choice for you – a cybersecurity expert on what to look for in a secure messaging app
Keeping your chats secure is a good idea, but end-to-end encryption is just the beginning of the list of options to consider when picking a messaging app.
The actual military grade (xmpp based) messengers implement security lables, meaning messages are tagged with the required security clearance and if you invite random people to a chat they can't see the messages.