CAS provides a solid and secure single sign on solution for web-based applications. When a user logs on to your CAS-enabled website, the CAS client checks with the CAS server to see if the user has been centrally authenticated. If not, the user is redirected to your CAS server's web-based login page where they enter their credentials, and upon successful authentication are redirected back to your client web application. If the user has been previously authenticated with the CAS server (with their 'ticket' being held as a session cookie), they are transparently allowed to go about their business.

This client requires a CAS server to talk to. You can obtain a Java implementation of such a server as well as more info about the CAS protocol here: http://www.ja-sig.org/products/cas

This CAS client library is designed to work easily with Rails, but can of course be used elsewhere.

1. cd into your Rails app's base directory
2. Run ruby script/plugin install -x http://svn.github.com/gunark/rubycas-client.git

3. Add the following to your config/environment.rb file: ``` require 'casclient' require 'casclient/frameworks/rails/filter'

   CASClient::Frameworks::Rails::Filter.configure( :cas_base_url => "https://cas.example.foo/" ) ```

   (Change cas.example.foo to your CAS server's base URL)

For detailed help and other install options please see http://rubycas-client.rubyforge.org

A Ruby implementation of a CAS server is now available at http://code.google.com/p/rubycas-server/