UML class diagram implementing Registration for login

I am trying to model a class diagram model where a user needs to login to a Java swing application. The user would have to register before being able to login. Here I have shown this through the composition relationship. I am not sure if this is correct. I feel Registration could be a generalisation of user and named "New user" but if this is the case I feel I would need to make another generalisation called "Returning user" but the User class and the the generalisation "Returning user" would have the exact same methods and attributes and so I assume this is wrong. I was wondering if someone could help me understand this part of the class diagram. Thanks in advance