Also check out https://threema.ch/en/ - it has the same functionality as WhatsApp (except of group chat), but secure/encrypted and is available for Android and iOS.
They're using the NaCl library for cryptography and proper encryption of messages before leaving the phone can be validated here: http://threema.ch/validation/
(I'm not affiliated with Threema, just a regular user who likes the product)
Comments
Also check out https://threema.ch/en/ - it has the same functionality as WhatsApp (except of group chat), but secure/encrypted and is available for Android and iOS.
They're using the NaCl library for cryptography and proper encryption of messages before leaving the phone can be validated here: http://threema.ch/validation/
(I'm not affiliated with Threema, just a regular user who likes the product)
I think Tox.im uses NaCl, too, but it's for PC only right now (it's new).