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Central Authentication Services (CAS) is a commonly used Single Sign-On
protocol used by many universities and large organizations. For a brief
introduction, please see the CAS website:


Minimum of PHP 5.6 with the following extensions: curl, openssl, dom, zlib, and xml


Install this module using the official Backdrop CMS instructions.

  • Navigate to Configuration > User accounts > CAS settings to configure the CAS module.

Differences from Drupal 7

  • cas_server is no longer included with base module. See Issues below for more information.


  • cas_server has been removed from the base module because of both its complexity and the inability to accurately and sufficiently test it.

Bugs and feature requests should be reported in the Issue Queue.

Current Maintainers

Rick Bargerhuff.

Seeking additional maintainers.


Ported to Backdrop CMS by Rick Bargerhuff.

Originally maintained for Drupal by:


This project is GPL v2 software.
See the LICENSE.txt file in this directory for complete text.