This module provides Single Sign-On with Google Apps Premier/Education.

Once configured, the only way for users to log in to their Google account
will be through their drupal account, so use caution before using this on
a live domain.

Requirements:

 1. Google Apps account with API access, meaning Premier and Eduction editions.

 2. xmlsec1 command-line tool installed on host and execable by PHP.
    See http://www.aleksey.com/xmlsec/

 3. Writable temp file directory on host.

 4. DSA/RSA keypair placed on host (outside of document root.)
    See http://code.google.com/apis/apps/articles/sso-keygen.html

 5. Drupal usernames must match Google usernames to authenticate.

Installation:

 1. Install this module.

 2. Configure settings at admin/settings/googleauth

 3. In Google Apps, under Advanced Tools, enable SSO, add your key and urls.
   Sign-in page url: http://hostname/googleauth/signin
   Sign-out page url: http://hostname/googleauth/signout
   Change password url: http://hostname (Users change password via Drupal, so
     set this as appropriate.)

Visitors to the Google Apps domain who need authentication will then be
redirected to the Drupal site.  If not logged in, they will get a Drupal
login form.  Once authenticated, they are redirected back to google.

