diff --git a/Classes/Controller/SsoController.php b/Classes/Controller/SsoController.php
index c46dae0..8adc214 100644
--- a/Classes/Controller/SsoController.php
+++ b/Classes/Controller/SsoController.php
@@ -35,6 +35,13 @@ use \TYPO3\CMS\Extensionmanager\Utility\ConfigurationUtility;
 class SsoController extends ActionController
 {
 
+    /**
+     * Configuration Utility (see definitions in ext_conf_template.txt).
+     *
+     * @var    \TYPO3\CMS\Extensionmanager\Utility\ConfigurationUtility $configurationUtility
+     * @inject
+     */
+    public $configurationUtility;
 
     /**
      * Compare if signed data matches given signature.
@@ -70,10 +77,12 @@ class SsoController extends ActionController
      */
     public function authenticateAction()
     {
-        /** @var \TYPO3\CMS\Extensionmanager\Utility\ConfigurationUtility $configurationUtility */
-        $configurationUtility = $this->objectManager->get(\TYPO3\CMS\Extensionmanager\Utility\ConfigurationUtility::class);
-        $extensionConfiguration = $configurationUtility->getCurrentConfiguration('tx_dj_discourse_sso');
+        $extKey = 'dj_discourse_sso';
 
+        /** @var \TYPO3\CMS\Extensionmanager\Utility\ConfigurationUtility $configurationUtility */
+        $extensionConfiguration = $this->configurationUtility->getCurrentConfiguration($extKey);
+
+        GeneralUtility::devLog('authenticateAction', $extKey, 0, array('config' => $extensionConfiguration));
         // Check mandatory settings.
         if (isset($extensionConfiguration['redirect_url']) === false) {
             $errorText = '<div><b>ERROR!</b> '
@@ -105,8 +114,11 @@ class SsoController extends ActionController
             $redirectStatus = 303;
         }
 
-        $hmac = hash_hmac('sha256', $sso, $this->settings['discourse_sso_shared_key']);
+        $sso  = urldecode(GeneralUtility::_GP('sso'));
+        $sig  = GeneralUtility::_GP('sig');
+        $hmac = hash_hmac('sha256', $sso, $sharedKey);
         if ($this->_hashsAreEqual($hmac, $sig) === false) {
+            GeneralUtility::devLog('authenticateAction bad request', $extKey, 0, array('sso' => $sso, 'sig' => $sig, 'hmac' => $hmac));
             header('HTTP/1.1 403 Forbidden');
             $this->throwStatus(403, 'Bad SSO request');
         } else {
@@ -121,8 +133,6 @@ class SsoController extends ActionController
             }
 
             if (isset($user) === true) {
-                $sso         = urldecode(GeneralUtility::_GP('sso'));
-                $sig         = GeneralUtility::_GP('sig');
                 $userId      = $user['uid'];
                 $userEmail   = $user['email'];
                 $userName    = $user['username'];
@@ -139,6 +149,7 @@ class SsoController extends ActionController
                 $signature   = hash_hmac('sha256', $payload, $this->settings['discourse_sso_shared_key']);
                 $query       = http_build_query(array('sso' => $payload, 'sig' => $signature));
                 $redirectUrl = $redirectUrlRoot.'/session/sso_login?'.$query;
+                GeneralUtility::devLog('authenticateAction successful, redirecting', $extKey, 0, array('redirectUrl' => $redirectUrl, 'status' => $redirectStatus));
                 $this->redirectToUri($redirectUrl, 0, $redirectStatus);
             } else {
                 // No user logged in.
@@ -147,6 +158,7 @@ class SsoController extends ActionController
                     .'You should not see this message!<br />'
                     .'This plugin should be made available only, if a Frontend User is logged in.<br />'
                     .'Please change this in the setup of this content element.';
+                GeneralUtility::devLog('authenticateAction bad configuration', $extKey, 0, array('error' => $errorText));
                 return $errorText;
             }//end if
         }//end if