I want to create a simple user authentication system (without using databases!!) containing only a few user names and passwords.

I then want to open a welcome page that says 'Hi <name>, where the name differs to the login username (which is just an alias). I also want to enable the user to enter other variables when prompted, which can be stored on the server side and deleted at the completion of the session (these variables being weight and height).

In addition, I know the sex of the users, so want this hard-coded (and not deleted with the other session variables) to be associated with each user.

How do I attack this problem...any code or ideas will be greatly appreciated and considered.