Add support for encrypted SMS

[rradar]

Hey!

Would be awesome if the communication could be 'proper' secured. I think using the silence (https://github.com/SilenceIM/Silence) stack which is based on signal (https://github.com/signalapp/Signal-Android) and is using up to date encryption technologies: Double Ratchet Algorithm (https://en.wikipedia.org/wiki/Double_Ratchet_Algorithm)

Sending the commands in clear text is no good anymore in 2018 (in 2017 it wasn't ether...)

And if there is a end-to-end encrypted communication there could even a defined pass or secret be used when sending commands.. (or just use and validate the keys from the sender!) :+1:

[cyrpaut]

As a user of Silence in my company, I strongly support this feature request with the perspective of RC being a first class anti-theft app.