Joomla session credentials to third party app

[cybersnac]

I'm not sure if this is the right place to ask this questions but here goes.

 

I'm hosting a site using Joomla CMS. My goal is to have users log into the Joomla site with the credentials they register with and then use those credentials to authenticate with a third party application.

 

Is there a way to call the credentials for a specific user in PHP code? The order of operations should go something like this:

 

1. User enters credentials on Joomla site.

2. User is authenticated with the MySQL DB that Joomla uses.

3. Credentials supplied are sent to a 3rd party web server using a post action on a php page. The URL to that server looks like this: https://www.testserver.com/login.php?action=login

 

3. User is redirected to a logged in session page on the joomla site.

4. User clicks on a link to pre-authenticated 3rd party site and a logged in session page is brought up on that server.

 

I'm not sure that made complete sense. Any help would be appreciated.

 

I should note that I have a module for Joomla that passes credentials to this server successfully but I'm trying to control the login to this server through the joomla site, therefore, currently the users have to log in to the joomla site 1st and then log in AGAIN to the 3rd party server. I would like to avoid the double login and get a basic implementation of single sign-on happening here.