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Table of Contents

• Overview
• Before You Register Your Application URL
• Register Your Application URL
• Web Login process
  • Conventions & Definitions
  • CAS URIs
  • Login Securely
  • Ticket Validation (CAS protocol 1.0, AuthN, simple text response)
  • Ticket Validation (CAS protocol 2.0, AuthN, XML response)
  • Ticket Validation (CAS protocol 3.0, AuthN with attributes, SAML response)
  • Logging Out
• Access Control
• Sample Clients
  • Java CAS client
  • UH CAS Demo in Java
  • phpCAS
  • cURL (no attributes requested)
  • CAS Authentication with Spring Security
• Frequently Asked Questions
• Troubleshooting
• Technical Support

...

UH Login (CAS) is available for University of Hawaiʻi (UH) Web site developers to authenticate users with their UH username and password.

Overview

UH Login (CAS) is available for University of Hawaiʻi (UH) Web site developers to authenticate users with their UH username and password. It alleviates the problem of having to develop a user authentication system as part of the Web-enabled application (web application) development. It also provides increased security for users by not allowing Web applications to handle their passwords (often using insecure means such as sending it in the clear or unnecessarily storing it).

...

...

Before You Register Your Application URL …

Before you register your application URL there are a few details to first consider:

1. Will authentication include the release of attributes to your application?
   1. If yes, UH Data Governance guidelines apply.  For each unique application you must submit a separate request.  What that means is that you cannot register a single URL and host multiple applications under it.  
2. Is your application hosted on a non-UH server?
   1. If yes, your request may be subject to the UH Data Sharing Request process. Please send an inquiry to datagov@hawaii.edu or call (808) 956-7487.

...

Register Your Application URL

For security purposes, application URLs must be registered in order to prevent unauthorized use.

• Registration Form

...

Web Login process

Web applications registered for UH Login use a link or redirect from their main page to the secure HTML CAS form.

To Authenticate Users

• A user enters their UH username and password on the UH Login page.
• After submission, the Web Login Service redirects the user back to your web application along with a service ticket provided by the Web Login Service.
• Your web application then requests that UH Login validate this ticket.
  • If the user supplied the correct authentication credentials (username/password), UH Login will return a success response to your web application.
  • Otherwise, a failure response is returned.

...

...

...

Conventions & Definitions

• "Client" refers to the end user and/or the web browser.
• "Server" refers to UH Login (CAS).
• "Service" refers to the application the client is trying to access (i.e., your application).
  • "TARGET" for samlValidate
• <LF> is a bare line feed (ASCII value 0x0a).

...

CAS URIs

URIs for CAS use the hostname followed by /cas and ended with the desired service. In the examples that follow, substitute the following for $WEBLOGIN-HOST for the appropriate environment.

• Production
  • https://authn.hawaii.edu/
• Test
  • https://cas-test.its.hawaii.edu/ (testing does not require registration of your URL)
• Future Test
  • https://cas-future-test.its.hawaii.edu/
• Deprecated Production
  • cas-deprecated.its.hawaii.edu

Append the following as needed:

• Login securely
  • cas/login
    • provides service ticket
• Ticket validation
  • cas/validate
    • Use HTTP GET
    • CAS protocol v1.0
    • response is text delimited by <LF>
  • cas/serviceValidate
    • Use HTTP GET
    • CAS protocol v2.0
    • response is XML
  • cas/samlValidate
    • Use HTTP POST
    • provides attributes
    • response is SAML 1.1
• Logout, destroy service tickets.
  • cas/logout

If your service is only interested in authenticating users and will not require a user object of released attributes, you should use either cas/validate or cas/serviceValidate. Their responses

...

...

...

Log in Securely

...

/login

To have a user login securely put a link on your main page to the "login securely" URL with a request parameter named service and having a value that is the Service URL (i.e., the URL of the main page or a page that will be able to handle an HTTP request with a parameter). This link should be labeled with something like "Login Securely" to establish in your user's mind that the password will not be seen by your application and is handled securely. See the next section on ticket validation for information about how your application finds out the username.

...

• service

  • used for AuthN responses
  • validate service ticket with
    • cas/validate
    • cas/serviceValidate
    • cas/samlValidate
• renew (OPTIONAL)
  • if this parameter is set, single sign-on will be bypassed. In this case, CAS will require the client to present credentials regardless of the existence of a single sign-on session with CAS.
• other parameters are described on the CAS Protocol wiki page

The service parameter should be set to the URL that the Web Login service will redirect the client to after successful authentication, as well as where the Web Login service will direct success/failure responses.

...

• Redirect the client to the URL specified by the "service" parameter with a service ticket in a manner that will not cause the user's credentials to be forwarded to the your web application. The client uses the ticket provided as a parameter to one of CAS's validation methods.
  • cas/validate
    • Use HTTP GET
    • CAS protocol v1.0
    • response is text delimited by <LF>
  • cas/serviceValidate
    • Use HTTP GET
    • CAS protocol v2.0
    • response is XML
  • cas/samlValidate
    • Use HTTP POST
    • provides attributes
    • response is SAML 1.1

...

...

Ticket Validation (CAS protocol 1.0

...

, AuthN, simple text response)

/validate

This section describes how your Web application finds out the username of a user that has successfully logged in.

...

• Here's an example of the URL used by UH Login to redirect the request back to the Web site (with a sample ticket):

  No Format
  https://myserver/myapp?ticket=ST-3-8tkkJbPThesE1cZjVVtc

  
  

• The server-side processing of your Service URL must validate the extracted authentication token by sending an HTTP GET request with the following parameters:

  No Format
  service=<Service URL> ticket=<service ticket>

  
  

• Using your URL with ticket, send your request to UH Login:

  No Format
  https://$WEBLOGIN-HOST/cas/validate?service=https://myserver/myapp&ticket=ST-95-a1kjb6g4Tcdeh17vfy6g

  
  

  Info
  Append &renew=true to disallow SSO.

  
  

• After validating the service ticket, UH Login will return a text document indicating success or failure.

  Code Block
  xml xml title On ticket validation success:
  yes<LF> username<LF>

  
  

  Code Block
  xml xml title On ticket validation failure:
  no<LF> <LF>

...

...

Ticket Validation (

...

CAS protocol 2.0, AuthN, XML response)

...

/serviceValidate

This section describes how your Web application finds out the username of a user that has successfully logged in.

...

• Here's an example of the URL used by UH Login to redirect the request back to the Web site (with a sample ticket):

  No Format
  https://myserver.example.edu/myapp?ticket=ST-7655-K6dyN9ystYwdOZynSnak-cas

  
  

• The server-side processing of your Service URL must validate the extracted authentication token by sending an HTTP GET request with the following parameters:

  No Format
  service=<Service URL> ticket=<service ticket>

  
  

• Using your URL with ticket, send your request to UH Login:

  No Format
  https://$WEBLOGIN-HOST/cas/serviceValidate?service=https://myserver.example.edu/myapp&ticket=ST-7655-K6dyN9ystYwdOZynSnak-cas

  
  

  Info
  Append &renew=true to disallow SSO.

  
  

• After validating the service ticket, UH Login will return an XML-fragment indicating success or failure.

  Code Block
  xml xml title On ticket validation success:
  <cas:serviceResponse xmlns:cas='http://www.yale.edu/tp/cas'> <cas:authenticationSuccess> <cas:user>joebogus</cas:user> </cas:authenticationSuccess> </cas:serviceResponse>

  
  

  Code Block
  xml xml title On ticket validation failure:
  <cas:serviceResponse xmlns:cas='http://www.yale.edu/tp/cas'> <cas:authenticationFailure code="INVALID_TICKET"> Ticket ST-7655-K6dyN9ysFOOdOZynSnak-cas not recognized </cas:authenticationFailure> </cas:serviceResponse>

  
  

  Info
  title Error codes
  The following values may be used as the "code" attribute of authentication failure responses. INVALID_REQUEST not all of the required request parameters were present INVALID_TICKET the ticket provided was not valid, or the ticket did not come from an initial login and "renew" was set on validation. The body of the <cas:authenticationFailure> block of the XML response SHOULD describe the exact details. INVALID_SERVICE the ticket provided was valid, but the service specified did not match the service associated with the ticket. CAS MUST invalidate the ticket and disallow future validation of that same ticket. INTERNAL_ERROR an internal error occurred during ticket validation

...

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...

Ticket Validation (

...

CAS protocol 3.0, AuthN with attributes, SAML response):

/samlValidate

This section describes how your Web application determines the username and possibly additional attributes for a user that has successfully logged in.

...

...

Logging Out (SLO)

...

/logout

Web applications that login a user must handle their own session state and should offer the user the ability to log out of their session. Without the logout service provided by CAS, a user returning to the web application's Service URL, will be automatically logged back in because of the ticket-granting cookie also provided by CAS stored by the client. This is a single sign-on feature across web applications that use UH Login. There are two basic ways to "log out"; logout from application and UH Login single sign-on or logout from application and force re-authentication to UH Login.

...

Parameters

• service (OPTIONAL)
  • the identifier of the service to redirect to after logging out
  • the service parameter must be also be a registered service URL

• url (DISABLED)

  Note

  Although Aperero's CAS protocol documentation describes the use the the url parameter, the Aperero developers have disabled it in recent versions of CAS to prevent potential abuse. Their explanation of the situation may be found in this thread from the cas-users mailing list. The url parameter defined in the former CAS 2.0 specification is not a valid parameter in CAS 3.0 anymore. CAS Servers MUST ignore given url parameters.

  
  

Examples

• To logout a user and prevent her from automatically logging back into a Web application, the Web application can forward the user to the Logout URL of UH Login. That URL will destroy the ticket-granting cookie that enables the single sign-on feature and gives the user a page that informs them that they have logged out of UH Login.

  No Format
  https://$WEBLOGIN-HOST/cas/logout

  
  

• To logout a user and prevent her from automatically logging back into a Web application, the Web application can forward the user to the Logout URL of UH Login. That URL will destroy the ticket-granting cookie that enables the single sign-on feature and redirect the user to the URL identified by the service parameter.

  No Format
  https://$WEBLOGIN-HOST/cas/logout?service=https://myserver/myapp

  
  

  Info
  The URL provided by the service parameter must be registered to use UH Login.

  
  

...

Access Control

It is every developer's responsibility to perform any necessary access control (authorization, AuthZ) after a user has logged on to their Web site. This is may be done by using information as attributes for the user. The affiliation, campus, or campus affiliation data should be enough to filter out unauthorized users. Alternatively, you choose explicitly may allow or disallow by username. Ultimately, it is up to each developer to determine how to implement access controls based on available information.

...

Sample Clients

• Apereo documentation on CAS clients
• Jasig CAS Client for Java - Spring Boot Support

...

Java client

Aperero provides an example of SAML 1.1 Ticket Validation Filter.

...

...

UH CAS Demo in Java

UH ITS' own Frank Duckart wrote the following CAS demo using Java and Servlets:

...

Probably not a great idea, but it is also possible to create a CAS client login using JSP only:
Project Repo:  https://github.com/fduckart/uh-jsp-casdemo

...

phpCAS client

The phpCAS module is a PHP library that interacts with CAS and allows you to work with user and authentication objects. It also allows for attribute release. You can download and extract the The latest phpCAS version from http://downloads.jasig.org/cas-clients/php/current.tgz. may be obtained from the phpCAS Github page. Documentation for phpCAS can be found here.

It is recommended after you extract the release that you create a symlink in the directory to the CAS folder. For example, if your phpCAS release is located in /usr/lib/php/CAS-1.3.1, you would create the symlink in /usr/lib/php. This allows you to have multiple versions of phpCAS without the need to continually overwrite folders.

...

<?php

/**
 * The purpose of this central config file is configuring all examples
 * in one place with minimal work for your working environment
 * Just configure all the items in this config according to your environment
 * and rename the file to config.php
 *
 * PHP Version 57
 *
 * @file     config.php
 * @category Authentication
 * @package  PhpCAS
 * @author   Joachim Fritschi <jfritschi@freenet.de>
 * @author   Adam Franco <afranco@middlebury.edu>
 * @license  http://www.apache.org/licenses/LICENSE-2.0  Apache License 2.0
 * @link     https://wiki.jasig.org/display/CASC/phpCAS
 */

$phpcas_path = '/usr/lib/php/CAS-1.3.1/CAS../../source/';

///////////////////////////////////////
// Basic Config of the phpCAS client //
///////////////////////////////////////

// Full Hostname of your CAS Server
$cas_host = '$WEBLOGIN-HOSTcas.example.com';

// Context of the CAS Server.
// The phpCAS client will use this as the root directory for the CAS server and
// append the required page calls.
$cas_context = '/cas';

// Port of your CAS server. Normally for a https server it's 443
$cas_port = 443;

// Path to the ca chain that issued the cas server certificate (see above)
// If you are unable to set this path, you will not be
able to use the
// phpCAS::setCasServerCACert($cas_server_ca_cert_path) method
$cas_server_ca_cert_path = '/path/= '/path/to/cachain.pem';

//////////////////////////////////////////
// Advanced Config for special purposes //
//////////////////////////////////////////

// The "real" hosts of clustered cas server that send SAML logout messages
// Assumes the cas server is load balanced across multiple hosts
$cas_real_hosts = array('$WEBLOGIN-HOSTcas-real-1.example.com', 'cas-real-2.example.com');

// DatabaseClient config for PGT Storage, if used.
$db the required domain name, should be protocol, hostname and port
$client_service_name = 'pgsql:host=localhost;dbname=phpcashttp://127.0.0.1';

//$db = 'mysql:host=localhost;dbname=phpcas';
$db_user Client config for cookie hardening
$client_domain = 'phpcasuser127.0.0.1';
$db$client_passwordpath = 'mysupersecretpassphpcas';
$db$client_tablesecure = 'phpcastabel'true;
$driver$client_optionshttpOnly = '';

true;
$client_lifetime = 0;

// Database config for PGT Storage
$db = 'pgsql:host=localhost;dbname=phpcas';
//$db = 'mysql:host=localhost;dbname=phpcas';
$db_user = 'phpcasuser';
$db_password = 'mysupersecretpass';
$db_table = 'phpcastabel';
$driver_options = '';

///////////////////////////////////////////
// End Configuration -- Don't edit below //
///////////////////////////////////////////

// Generating the URLS for the local cas example services for proxy testing
if (isset($_SERVER['HTTPS']) && $_SERVER['HTTPS'] == 'on') {
    $curbase = 'https://' . $_SERVER['SERVER_NAME'];
} else {
    $curbase = 'http://' . $_SERVER['SERVER_NAME'];
}
if ($_SERVER['SERVER_PORT'] != 80 && $_SERVER['SERVER_PORT'] != 443) {
    $curbase .= ':' . $_SERVER['SERVER_PORT'];
}

$curdir = dirname($_SERVER['REQUEST_URI']) . "/";

// CAS client nodes for rebroadcasting pgtIou/pgtId and logoutRequest
$rebroadcast_node_1 = 'http://cas-client-1.example.com';
$rebroadcast_node_2 = 'http://cas-client-2.example.com';

// access to a single service
$serviceUrl = $curbase . $curdir . 'example_service.php';
// access to a second service
$serviceUrl2 = $curbase . $curdir . 'example_service_that_proxies.php';

$pgtBase = preg_quote(preg_replace('/^http:/', 'https:', $curbase . $curdir), '/');
$pgtUrlRegexp = '/^' . $pgtBase . '.*$/';

$cas_url = 'https://' . $cas_host;
if ($cas_port != '443') {
    $cas_url = $cas_url . ':' . $cas_port;
}
$cas_url = $cas_url . $cas_context;

// Set the session-name to be unique to the current script so that the client script
// doesn't share its session with a proxied script.
// This is just useful when running the example code, but not normally.
session_name(
    'session_for:-'
    . preg_replace('/[^a-z0-9-]/i', '_', basename($_SERVER['SCRIPT_NAME']))
);
// Set an UTF-8 encoding header for internation characters (User attributes)
header('Content-Type: text/html; charset=utf-8');
?>

...

//<?php

//**
phpCAS simple* clientAdvanced //example for require_once 'Config.php';

// import phpCAS lib
require_once $phpcas_path . 'CAS.php';

// This file will capture debugging output, useful to see what your client is doing.
// Make sure your application has read/write permissions.
phpCAS::setDebug( "/filepath/to/your/log/file" );

// initialize phpCAS
// If you are interested in the return of user attributes, use the following
// parameter
phpCAS::client( SAML with attributes and single logout
 *
 * PHP Version 7
 *
 * @file     example_advanced_saml11.php
 * @category Authentication
 * @package  PhpCAS
 * @author   Joachim Fritschi <jfritschi@freenet.de>
 * @author   Adam Franco <afranco@middlebury.edu>
 * @license  http://www.apache.org/licenses/LICENSE-2.0  Apache License 2.0
 * @link     https://wiki.jasig.org/display/CASC/phpCAS
 */

// Load the settings from the central config file
require_once 'config.php';
// Load the CAS lib
require_once $phpcas_path . '/CAS.php';

// Enable debugging
phpCAS::setLogger();
// Enable verbose error messages. Disable in production!
phpCAS::setVerbose(true);

// Initialize phpCAS
phpCAS::client(SAML_VERSION_1_1, $cas_host, $cas_port, $cas_context, $client_service_name);

// However, if you are only interested in user authentication, you can use
// the following:
// phpCAS::client( CAS_VERSION_2_0, $cas_host, $cas_port, $cas_context );

// For production use set the CA certificate that is the issuer of the cert
// on the CAS server and uncomment the line below.  Otherwise comment out this
// line and uncomment the phpCAS::setNoCasServerValidation() one
// Note, however, that if your App does not reside on the same server as CAS,
// you may run into problems determining the path to the certificate.
// port, $cas_context, $client_service_name);

// For production use set the CA certificate that is the issuer of the cert
// on the CAS server and uncomment the line below
phpCAS::setCasServerCACert($cas_server_ca_cert_path);

// For quick testing you can disable SSL validation of the CAS server.
// THIS SETTING IS NOT RECOMMENDED FOR PRODUCTION.
// VALIDATING THE CAS SERVER IS CRUCIAL TO THE SECURITY OF THE CAS PROTOCOL!
// phpCAS::setNoCasServerValidation();

// Handle SAML logout requests that emanate from the CAS host exclusively.
// Failure to restrict SAML logout requests to authorized hosts could
// allow denial of service attacks where at the least the server is
// tied up parsing bogus XML messages.
phpCAS::handleLogoutRequests(true, $cas_real_hosts);

// Force CAS authentication on any page that includes this file
phpCAS::forceAuthentication();

// Renew CAS authentication with renew=true on any page that includes this file
// Use this in place of phpCAS::forceAuthentication();
// phpCAS::renewAuthentication();

// Some small code triggered by the logout ifbutton
desired
if (isset($_REQUEST['logout'])) {
    phpCAS::logout();
}

?>

<html>
  <head>
    <title>phpCAS simple client< client with user attributes</title>
  </head>
  <body>

    Authentication succeeded for user
    <strong><?php echo phpCAS::getUser(); ?></strong>.

    <h3>User Attributes</h3>
    <ul>
    <?php
    foreach ( phpCAS::getAttributes() as $key => $value )
    {
        if ( is_array( $value ) )
        {
            echo '<li>', $key, ':<ol>';
            foreach ( $value as $item )
            {
                echo '<li><strong>', $item, '</strong></li>';
            }
            echo '</ol></li>';
        }
        else
        {
            echo '<li>', $key, ': <strong>', $value, '</strong></li>';
        }
    }
    ?>
    </ul>

    <p><a href="?logout=">Logout</a></p>g
  </body>
</html>

Theoretical examples of using CAS authentication across multiple pages, combined with using custom session variables.

==========================================
index.php (summarized)
This page authenticates the user to my application.  Here I check if the user
is authenticated, and if so, I capture the CAS3CAS session values and user
attributes.
==========================================
<?php

include_once( "../../lib/cas3cas.class.inc.php" )  
// This file is similar to the phpcas-test.php example
// The inclusion of this file activates the phpCAS client, and can
// trigger the authentication of the user if they're not logged in.
// My cas3cas.class.inc.php file is below this example.

// Display session values, to double-check what we have
// The value of $DEBUG is set in my app's configuration file.
// You will notice that the session id and name are set by CAS3.
if ( $DEBUG ) {
    if ( isset( $_SESSION ) ) {
        print "<p />SESSION values set<br />";
        print "Session ID: " . session_id() . "<br />";
        print "Session Name: " . session_name(). "<br />";
        print_r( $_SESSION );
        print "<p />";
    }
}

// Save the attributes
$cas_attributes = array();
foreach ( phpCAS::getAttributes() as $key => $value ) {
    $cas_attributes[$key] = $value;
    $DEBUG && print "phpCAS attribute: $key, Value: $value<br />";
}

// Save the token
$cas_token = session_id();

<!-- HTML form to log user into my application.  I've cut out elements like -->
<!-- the text fields  for username and password entry to focus on CAS3 session -->
<!-- Here, I am submitting the user attributes as hidden fields to the -->
<!-- next page that does the app authentication -->
<form action="app_authentication.php" name="logging_in" method="POST">
    <input type="hidden" name="state" value="cas3cas_authenticated" />
    <?php
    foreach ( $cas_attributes as $name => $attribute ) {
        if ( ! is_array($attribute) ) {
            print '<input type="hidden" name="cas_attributes['.$name.']" value="'.$attribute.'" />';
        }
        else {
            // Some CAS3CAS user attributes are multi-valued.
            foreach ( attribute as $sub_name => $sub_attr ) {
                print '<input type="hidden" name="cas_attributes['.$name.']['.$sub_name.']" value="'.$sub_attr.'" />';
            }
        }
    }
    ?>
    <input type="hidden" name="cas_token" value="<?php print $cas_token; ?>" />
</form>
?>

==========================================
cas3cas.class.inc.php
simplified version
==========================================
<?php
require_once "PHPCAS_CONFIG.php";       // this is my config file
require_once $phpcas_path . "CAS.php";  // import phpCAS

phpCAS::setDebug( "/filepath/to/where/i/store/app/logs/cas_debug.log" );
phpCAS::client( SAML_VERSION_1_1, $cas_host, $cas_port, $cas_context, $client_service_name );
phpCAS::setCasServerCACert( $cas_server_ca_cert_path );
phpCAS::handleLogoutRequests( TRUE, $cas_real_hosts );

// If the user isn't authenticated, force authentication
// Here is where we determine if a user has logged in via CAS3CAS
if ( ! phpCAS::isAuthenticated() ) {
    phpCAS::forceAuthentication();
}

if ( isset( $_GET['logout'] ) ) {
    phpCAS::logout();
}
?>

==========================================
app_authentication.php
This page just handles authenticating my application, as users have passwords
that are not the same as their UH account passwords.
==========================================
<?php

// IMPORTANT!
// Note that I do not include cas3cas.class.inc.php in this page!  If I did,
// phpCAS removes my app's session in order to use its own, and I end up losing
// the user-submitted form in the same process.

// Check if we have the POSTed "state" value of "cas3cas_authenticated" from index.php
if ( (! isset( $_POST['state']) ) || ($_POST['state'] != 'cas3cas_authenticated') ) {
    header( "Location: index.php?error=unauthenticated" );
    exit();
}

// Grab the username, app password, and CAS values
$entered_username   = $_POST[ 'username' ];
$entered_password   = $_POST[ 'password' ];
$cas_attributes     = $_POST[ 'cas_attributes' ];
$cas_token          = $_POST[ 'cas_token' ];

// Start a new session (non CAS session)
session_name( $PHP_SESS_ID );  // This is set in my app's config file so I can reuse and recall anywhere
if ( ! session_start() ) {
    die( "Could not start non-CAS session!" );
}

// Debugging statements, to ensure the values and constants are what I expect them to be.
// Note here that the session id and name should be values that I just set.
$DEBUG && print "
    <p />
    Session Name: ".session_name()."<br />
    Session ID: ".session_id()."<br />
    APP HOST: $APP_HOST<br />
    LDAP: $LDAP_HOST<br />
    Location: ".$_SERVER['PHP_SELF']."
    <p />
";

// Assume I have code to validate the user's name and password.
// Next I store the CAS attributes and token into my currently-active session ($PHP_SESS_ID)
if ( $user_validated ) {
    $_SESSION[ $CAS_ATTRIBUTES  ] = $cas_attributes;
    $_SESSION[ $CAS_TOKEN       ] = $cas_token;
}
?>

==========================================
all other pages in my application
Now that I have stored the CAS3CAS token and attributes, I can access them
in the rest of my application.
==========================================
<?php

// I still do not include the cas3cas.class.inc.php page

# Start a new session (non CAS session)
session_name( $PHPSESSID );
if ( (! isset( $_SESSION)) || (! $_SESSION) ) {
    if ( ! session_start() ) {
        die( "Cannot start non-CAS session!");
    }
}

// Here I check that the user has a CAS3CAS token (which was set in app_authentication.php)
if ( (! isset( $_SESSION[$CAS_TOKEN] )) || ($_SESSION[$CAS_TOKEN] == $EMPTY_STR) ) {
    $file->write_log_file( "Unauthenticated access to ".$_SERVER['PHP_SELF'], $LOG_DIR.$LOG_WEBLOG );
    header( "Location: index.php?error=unauthenticated" ); // index.php has an error-handler.
    exit();
}

$cas_attributes         = $_SESSION[ $CAS_ATTRIBUTES ];
$uh_username            = $cas_attributes[ $UID ];
$uh_number              = $cas_attributes[ $UHUUID ];

// session id and name should still be the values I set, not CAS3CAS's values.
// You could also include the CAS3CAS values in this debug statement if you
// wanted to verify retention and accuracy.
$DEBUG && print "
    <p />
    Session Name: ".session_name()."<br />
    Session ID: ".session_id()."<br />
    APP HOST: $APP_HOST<br />
    LDAP: $LDAP_HOST<br />
    USER: $uh_username<br />
    UHUUID: $uh_number<br />
    Location: ".$_SERVER['PHP_SELF']."
    <p />
";
?>

...

Array ( [0] => yes [1] => jschmidt [2] => )

...

cURL client (no attributes requested)

Below is a PHP script using cURL to establish a connection with the CAS server.

...

<?php
# Test CAS URLs
$CAS_LOGIN_URI      = "https://$WEBLOGIN-HOST/cas/login";
$CAS_VALIDATE_URI   = "https://$WEBLOGIN-HOST/cas/validate";
$CAS_LOGOUT_URI     = "https://$WEBLOGIN-HOST/cas/logout";

$single_signon = TRUE;

# Here is where we check if the user has authenticated.  If we cannot find a ticket,
# redirect the user to the CAS login page.
if ( ! isset($_GET["ticket"]) )
{
    $location = "Location: ".$CAS_LOGIN_URI."?service=".urlencode($_SERVER["SCRIPT_URI"]);

    # If we haven't enabled single sign-on, the user has to renew each time.
    if ( ! $single_signon )
    {
        $location = $location."&renew=true";
    }

    header($location);
    exit();
}
else
{
    # Initialize our CURL session with the CAS validation URL.  Supply the server script and ticket.
    $validate_string    = $CAS_VALIDATE_URI."?service=".urlencode($_SERVER["SCRIPT_URI"])."&ticket=".$_GET["ticket"];

    $ch = curl_init($validate_string);

    # set the option to return the results
    curl_setopt($ch, CURLOPT_RETURNTRANSFER, TRUE);

    $cas_return = explode("\n", curl_exec($ch));

    # This dumps out the return values from our cURL request.  Later we check whether or not the user successfully authenticated.
    echo "CAS return via cURL: ";
    print_r($cas_return);
    echo "<br />";

    if ( $cas_return[0] == "yes" )
    {
        echo "User successfully authenticated via CAS<br />";
        for ( $i=0; $i<count($cas_return); $i++ )
        {
            echo "Cas Return #$i: ".$cas_return[$i]."<br />";
        }
    }
    else
    {
        echo "User not validated<br />";
    }
}

?>

...

...

Spring Security CAS Authentication

...

• http://docs.spring.io/spring-security/site/docs/4.0.4.RELEASE/reference/htmlsingle/#cas

...

Frequently Asked Questions (FAQ)

Why does my site automatically login a returning user after they logout of their session with my site?

...

A future enhancement could make single sign-on an option for the user so the default will be no single sign-on. If the user chooses to enable single sign-on when authenticating to UH Login, only those apps that don't use the renew parameter will permit single sign-on if the user doesn't logout via the Logout URL from a previously visited app.

Why can't I login successfully to the CAS test environment?

There are several reasons for this and one or both may be applicable:

1. Currently you need to use a UH VPN to access CAS test.  (not a requirement for production CAS, nor will it ever be)
2. CAS test points to a test LDAP instance that may not have your current password.  Send an email to the IAM team to request a "password sync" if needed.

Can anyone use my Web site?

Anyone that is in the UH Core LDAP Directory Service. In other words, current people in the UH System (ten campuses, system offices, some RCUH employees) and visitors (temporary guest accounts) managed by VIA. See the overview 13402875 above.

Why is the UH CAS Server sending requests to my webapp?

...

Since this feature is not compatible with our existing business rules, IAM will be disabling this feature during the 2014 calendar year.

...

Troubleshooting

...

Application Not Authorized to Use UH Login

Problem:

Your application cannot successfully authentication against CAS.

Example error message:

Solutions:

...

Reference: CAS Users mailing list thread on time synchronization

...

...

Technical Support

There is an active UH community of developers and a good chance that at least one of them has experience with your scenario.  It is well worth joining this community's email list if you've not already done so.  For details, visit App Developers Forum page.  Note that the ITS Identity and Access Management team also participates on this list.