M1

Protocols keep data safe by many ways, for example you could set a code or a password or even a lock on to your phone if you want to keep your phone safe and people not looking through you phone, setting a lock/password/code is very useful for your phone sometimes because if you loose your phone and someone finds won't able to get on to the phone. 

Another example is if you got an internet wi fi connection at home it most likely have a password written at back of the wi fi box for you to remember and keep it safe from other people trying to connect to it.

You can keep your Bluetooth safe by setting a password or by simply turning it off.