By default, Gallery 3 has its own standalone authentication system. The user module stores information about each user in the database and can authenticate users by username and password. There are three types of users
However, Gallery 3 also comes with a pluggable authentication system that supports the concept of identity providers. An identity provider is an authentication system that can provide the following basic functions:
The user module provides this functionality in modules/user/libraries/drivers/IdentityProvider/Gallery.php and uses ORM to interact with User_Model and Group_Model for the data it needs.