The rewritten php-saml library, check url...
http://support.onelogin.com/entries/268420-saml-toolkit-for-php

Example:
<?php

use OneLogin\Saml\Settings;
use OneLogin\Saml\AuthRequest;
use OneLogin\Saml\Response;

$settings = new Settings();
$settings->idpSingleSignOnUrl = 'https://the-sso-provider.com'; // The URL to submit SAML authentication requests to.
$settings->idpPublicCertificate = file_get_contents("cert.pem"); // The x509 certificate used to authenticate the request.
$settings->spReturnUrl = "http://localhost:8080/manageResponse.php"; // The URL where to the SAML Response/SAML Assertion will be posted.
$settings->spIssuer = "some-app-id"; // The name of the application.

$request = new AuthRequest($settings);
$authUrl = $request->getRedirectUrl();

header("Location: " . $authUrl);
exit;

// now we are redirected to the SSO provider and than back...
// now when we are back- just continue...

$response = new Response($settings, $_POST['SAMLResponse']);

if($response->isValid()) {
    $response->getNameId(); // user id
    $response->getAttributes(); // additional attributes
    $response->getSessionNotOnOrAfter(); // time the session is valid until (Unix timestamp)
}