connecting with smartphone using hc-05

hello everyone, i wanted to make a lock that uses an app to change the password or to unlock it, the problem that i have is that i want only 1 smartphone to be able to connect, can i put the hc-05 in master mode and specify the address of the phone? or it won't work? also i want to know if the phone is present or not. thnks.

I believe the connection was discussed recently, using pair bind and link. I imagine the present/not-present condition can be derived from the STATE pin, which I believe is programmable. Failing that, there a swag of other pins that are not normally used, which may be investigated for this purpose. http://www.martyncurrey.com/connecting-2-arduinos-by-bluetooth-using-a-hc-05-and-a-hc-06-pair-bind-and-link/