I don't see the point of a password in Arduino. The pairing process involves a password in bluetooth.
You might mean binding. You can bind HC-05<>HC-0x. I believe this is done mainly for the auto-connect.
http://www.martyncurrey.com/connecting-2-arduinos-by-bluetooth-using-a-hc-05-and-a-hc-06-pair-bind-and-link/
It may be possible to do something similar with a phone<>BLE. I imagine this means configuring Bluetooth to only talk when the phone's MAC address is received. This probably involves writing a phone app as well.