Single sign on 10 different web sites
<p>I have 10 websites with different PHP related platforms like in Drupal, Joomla, Wordpress and Core PHP etc (Even includes sub domains also). </p>

<p>I want to create one new website with Registration and login functionality in Core PHP or else any framework. I want to implement single sign on functionality through this latest web site. So that can any one let me know the process to finish this.</p>
