Saving Hashed Passwords in my database.php

I never did it but I believe that you can use Encryption Library.

But anyway, your encryption key will remain on the server. An attacker able to enter your server will surely be able to decode your passwords. The processing time will also increase due to having to decrypt the password every time you access the database. Maybe it's better to use a more reliable hosting.

This library is not intended to be used for password handling, in fact you will see the note as soon as you begin to read the documentation. 

as of PHP 5.5.0 you can use password_hash to create a one way hash, and for verification you can use password_verify