Communicate with backend as safe as possible

I'm about to start the design of an application for Android (and possibly later on iPhone, if I ever get around learning 开发者_运维技巧it). In this application I will need to send and retrieve various information to a backend (that me myself also will need to design and code). The information will most likely be in json format.

How would I go about making this data as safely transmitted as possible? Is https the only anser to this? Or are there any other smart solutions to this?

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TLS (including HTTPS), where you validate the certificates from the client and the server is the safest mechanism, and doesn't require you to reinvent authentication in some flawed way.