A secure text messaging app I like and use is Threema (http://threema.ch/en/index.html http://threema.ch/en/index.html). All servers are allegedly located in sw

A secure text messaging app I like and use is Threema (http://threema.ch/en/index.html http://threema.ch/en/index.html). All servers are allegedly located in switzerland. The app uses public-private-key end-to-end encryption. You can exchange keys locally via QR code and it is available for both Android and iOS. You can still sync your phonebook in whatsapp style. It's a good compromise between being secure and being pragmatic to me. However, it's not open source, so you still have to trust the app (and the OS) not to send out your private key.