Joomla Authentication on 2nd Website -- 2

We are looking for someone to develop a Joomla Plugin that will allow us to use our exsiting Joomla website as the authentication backend for a 2nd website. The 2nd website is currently all HTML but will be converted to a PHP site. On the 2nd Site, we need a php script that can be required on our existing pages. This script will present the user with a login form. They will enter their Joomla Username and password. The script will then talk to the Joomla server and (a) Verify username and password and (b) check what user groups they are part of. The script must be able to check to see if the user is in the proper group. This group ID changes page to page. require("[login to view URL]"); I have 2 Websites. One of them ([login to view URL]) is running Joomla, and a 2nd Website ([login to view URL]) runs a static PHP website. We would like to make it so that when users go to [login to view URL] they are prompted for a login. They will enter their Server1. JOOMLA ACCOUNT and it then talk to joomla, and A, check that username and password are correct and B, check to see if they are in the Access Level or Group that is specified. Once that is checked and equals TRUE, it will allow them to access the website.