Index: kernel/user/module.php
===================================================================
--- kernel/user/module.php	(revision 23151)
+++ kernel/user/module.php	(working copy)
@@ -104,7 +104,7 @@
 $ViewList['register'] = array(
     'functions' => array( 'register' ),
     'script' => 'register.php',
-    'params' => array( ),
+    'params' => array( 'redirect_number' ),
     'ui_context' => 'edit',
     'default_navigation_part' => 'ezmynavigationpart',
     'single_post_actions' => array( 'PublishButton' => 'Publish',
Index: kernel/user/register.php
===================================================================
--- kernel/user/register.php	(revision 23151)
+++ kernel/user/register.php	(working copy)
@@ -28,6 +28,7 @@
 
 $http = eZHTTPTool::instance();
 $Module = $Params['Module'];
+$redirectNumber = $Params['redirect_number'];
 
 if ( isset( $Params['UserParameters'] ) )
 {
@@ -57,6 +58,34 @@
 // Create new user object if user is not logged in
 if ( !$http->hasSessionVariable( "RegisterUserID" ) )
 {
+    // flag for user client that supports cookies and session validates
+    $userClientValidates  = true;
+    $doValidationRedirect = false;
+    if ( !eZSession::userHasSessionCookie() )
+    {
+        if ( $redirectNumber == '2' )
+            $userClientValidates = false;
+        else
+            $doValidationRedirect = true;
+    }
+    else if ( !eZSession::userSessionIsValid() )
+    {
+        if ( $redirectNumber == '2' )
+            $userClientValidates = false;
+        else
+            $doValidationRedirect = true;
+    }
+
+    if ( $doValidationRedirect )
+    {
+        return $Module->redirectTo( '/user/register/2' );
+    }
+    else if ( !$userClientValidates )
+    {
+        return $Module->handleError( eZError::KERNEL_ACCESS_DENIED, 'kernel' );
+    }
+    // else create user object
+    
     $ini = eZINI::instance();
     $errMsg = '';
     $checkErrNodeId = false;
@@ -94,7 +123,7 @@
                                                        'is_main' => 1 ) );
     $nodeAssignment->store();
 }
-else if ( $http->hasSessionVariable( "RegisterUserID" ) )
+else
 {
     $userID = $http->sessionVariable( "RegisterUserID" );
 }
Index: lib/ezutils/classes/ezsession.php
===================================================================
--- lib/ezutils/classes/ezsession.php	(revision 23151)
+++ lib/ezutils/classes/ezsession.php	(working copy)
@@ -104,9 +104,16 @@
      *
      * @access protected
      */
-    static protected $hasSessionCookie = false;
+    static protected $hasSessionCookie = null;
 
     /**
+     * Flag if user session validated when reading data from session, set in {@link eZSession::internalRead()}.
+     *
+     * @access protected
+     */
+    static protected $userSessionIsValid = null;
+
+    /**
      * User session hash (ip + ua string), set in {@link eZSession::registerFunctions()}.
      *
      * @access protected
@@ -187,8 +194,13 @@
                     eZDebug::writeNotice( 'User ('. $sessionRes[0]['user_id'] .') hash did not match, regenerating session id for the user to avoid potentially hijack session attempt.', 'eZSession::internalRead' );
                     self::regenerate( false );
                     self::$userID = 0;
+                    self::$userSessionIsValid = false;
                     return false;
                 }
+                else if ( self::$userSessionIsValid === null )
+                {
+                    self::$userSessionIsValid = true;
+                }
                 self::$userID = $sessionRes[0]['user_id'];
             }
             $ini = eZINI::instance();
@@ -586,6 +598,33 @@
     }
 
     /**
+     * Returns if user had session cookie at start of request or not.
+     * 
+     * @return bool|null returns null if session is not started yet.
+     */
+    static public function userHasSessionCookie()
+    {
+        return self::$hasSessionCookie;
+    }
+
+    /**
+     * Returns if user session validated against stored data in db
+     * or if it was invalidated during the current request.
+     * 
+     * @return bool|null returns null if user is not validated yet.
+     */
+    static public function userSessionIsValid()
+    {
+        // force a session read if session has started but not yet used
+        if ( self::$userSessionIsValid === null &&
+             self::$hasSessionCookie === true )
+        {
+            $tempSession = $_SESSION;
+        }
+        return self::$userSessionIsValid;
+    }
+
+    /**
      * Adds a callback function, to be triggered by {@link eZSession::triggerCallback()}
      * when a certan session event occurs.
      * Use: eZSession::addCallback('gc_pre', myCustomGarabageFunction );