PHP/MySQL - Very secure login

I am looking to have a login script created. It will have to be VERY secure, sensitive data is being protected. -Must be protected from brute force attacks, all types of SQL/php injections, and hack proof. -After 2 hours of inactivity the user must be logged out. -5 Levels of accounts must be incorporated into this script: -Super admin (5) -admin (4) -employee (3) -contractor (2) -other (1) *Must also create a registration script to put new users in database Each level of account will have different privileges for what pages they can access. This must not be very difficult to incorporate into existing websites (preferably using functions) I DO NOT WANT TO SEE YOUR PORTFOLIO OF PREVIOUS UNRELATED WORK! ANY BID THAT INCLUDES NON-RELATED WORK WILL BE IGNORED! Please include a message on how you would build my secure login script.