@jonw Are you aware of this:
https://en.wikipedia.org/wiki/BlackBerry#Security_agencies_access
https://www.theregister.co.uk/2016/04/18/blackberrys_john_chen_security_response/
It seems #Blackberry is a very insecure platform, unfortunately. The entire OS may be compromised, with data sent to governments via official Blackberry channels (regardless of just cause). :o