The Authentication Managers in PicketBox are tasked with authenticating users against a database, ldap or file based storage. You are free to write your own authentication manager.
You can always provide your own implementation.
To plug your own authentication manager you need to implement the org.picketbox.core.authentication.AuthenticationManager interface or extend org.picketbox.core.authentication.AbstractAuthenticationManager base class. You would prefer to use the base class because it provides default implementations for some methods (eg.: life cycle methods).
After creating your own authentication manager class you need to register it. If your are using the Configuration API take a look at the documentation.