SimpleSAMLphp

I have previously talked about configuring a Drupal site to authenticate against a remote SimpleSAMLphp install, but as Drupal is an excellent user management system I wanted to turn it around and use Drupal as the identity provider. This means that Drupal would allow users to log into other systems using their Drupal username and password by leveraging the power of SimpleSAMLphp.

This can be accomplished by wrapping the Drupal site and SimpleSAMLphp together along with a couple of modules to power the communication between the two systems.

The same terms apply as I described in the previous post, but to reiterate their meaning in this context I will go over them again.

I have previously talked about installing SimpleSAMLphp using composer, so the next step is setting up the system to actually provide authentication against a SimpleSAMLphp system. As I spend a lot of time using Drupal I wanted to set up the authentication with Drupal and SimpleSAMLphp in order to see how things worked.

First, let's define a couple of terms that are important to this setup.

SP - Service Provider - This is the system that users are trying to log into, which in this setup is Drupal. The Drupal site is providing a 'service' and as such users want to authenticate with it. Service providers will generally create a local user to track the user within the site, although that's not always the case.

Security Assertion Markup Language (SAML) is a standard that passes authentication credentials between hosts and essentially allows for a single sign on solution to be created. The standard uses XML files that get passed between the authentication system (known as the identity provider or IdP) and the service users want to sign into (known as the service provider or SP). 

SimpleSAMLphp is an open source application that implements SAML mechanisms and allows for the authentication system to be created as well as some administration tasks to be performed. The system is robust and battle tested, having been integral to the open source authentication systems for a number of years.