Anybody using Signal for secure messaging is misguided. Any one of your recipients could be using the desktop app and there’s no way to know unless they tell you.

That’s why I only communicate face-to-face inside of a soundproofed faraday cage.

If the app manages the keys, then you can’t trust the app.

If the recipient manages their own keys, then you can’t trust the recipient.

Encryption is fundamentally insecure. Once I encrypt something, nobody should be able to decrypt it ever again.