diff --git a/lib/installer.php b/lib/installer.php
index 49ba44926323c8eb6054c8cdf58ceacd911db7d1..dcd29f9e1ade6571e44f49f62c0aa1f14df1da7d 100644
--- a/lib/installer.php
+++ b/lib/installer.php
@@ -436,10 +436,30 @@ class OC_Installer{
 
 		$blacklist=array(
 			'exec(',
-			'eval('
+			'eval(',
 			// more evil pattern will go here later
-			// will will also check if an app is using private api once the public api is in place
 
+			// classes replaced by the public api
+			'OC_API::',
+			'OC_App::',
+			'OC_AppConfig::',
+			'OC_BackgroundJob::',
+			'OC_Config::',
+			'OC_DB::',
+			'OC_Files::',
+			'OC_Helper::',
+			'OC_Hook::',
+			'OC_Image::',
+			'OC_JSON::',
+			'OC_L10N::',
+			'OC_Log::',
+			'OC_Mail::',
+			'OC_Preferences::',
+			'OC_Request::',
+			'OC_Response::',
+			'OC_Template::',
+			'OC_User::',
+			'OC_Util::',
 		);
 
 		// is the code checker enabled?
diff --git a/lib/public/image.php b/lib/public/image.php
new file mode 100644
index 0000000000000000000000000000000000000000..dcecc077e2f501d0541ceed61938a2d5460b370e
--- /dev/null
+++ b/lib/public/image.php
@@ -0,0 +1,29 @@
+<?php
+/**
+* ownCloud
+*
+* @author Bart Visscher
+* @copyright 2013 Bart Visscher <bartv@thisnet.nl>
+*
+* This library is free software; you can redistribute it and/or
+* modify it under the terms of the GNU AFFERO GENERAL PUBLIC LICENSE
+* License as published by the Free Software Foundation; either
+* version 3 of the License, or any later version.
+*
+* This library is distributed in the hope that it will be useful,
+* but WITHOUT ANY WARRANTY; without even the implied warranty of
+* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+* GNU AFFERO GENERAL PUBLIC LICENSE for more details.
+*
+* You should have received a copy of the GNU Affero General Public
+* License along with this library.  If not, see <http://www.gnu.org/licenses/>.
+*
+*/
+
+namespace OCP;
+
+/**
+ * This class provides functions to handle images
+ */
+class Image extends OC_Image {
+}
diff --git a/lib/public/user.php b/lib/public/user.php
index 9edebe0e7cf5ccc822b84f59193867403ba3b6d7..23ff991642dfb7e9c457bb34c5c5698c9eaeceb0 100644
--- a/lib/public/user.php
+++ b/lib/public/user.php
@@ -40,7 +40,7 @@ class User {
 	 * @return string uid or false
 	 */
 	public static function getUser() {
-		return \OC_USER::getUser();
+		return \OC_User::getUser();
 	}
 
 	/**
@@ -50,7 +50,7 @@ class User {
 	 * Get a list of all users.
 	 */
 	public static function getUsers($search = '', $limit = null, $offset = null) {
-		return \OC_USER::getUsers();
+		return \OC_User::getUsers($search, $limit, $offset);
 	}
 
 	/**
@@ -58,7 +58,7 @@ class User {
 	 * @return string display name
 	 */
 	public static function getDisplayName($user=null) {
-		return \OC_USER::getDisplayName($user);
+		return \OC_User::getDisplayName($user);
 	}
 
 	/**
@@ -68,7 +68,7 @@ class User {
 	 * Get a list of all display names and user ids.
 	 */
 	public static function getDisplayNames($search = '', $limit = null, $offset = null) {
-		return \OC_USER::getDisplayNames($search, $limit, $offset);
+		return \OC_User::getDisplayNames($search, $limit, $offset);
 	}
 
 	/**
@@ -78,7 +78,7 @@ class User {
 	 * Checks if the user is logged in
 	 */
 	public static function isLoggedIn() {
-		return \OC_USER::isLoggedIn();
+		return \OC_User::isLoggedIn();
 	}
 
 	/**
@@ -88,14 +88,14 @@ class User {
 	 * @return boolean
 	 */
 	public static function userExists( $uid, $excludingBackend = null ) {
-		return \OC_USER::userExists( $uid, $excludingBackend );
+		return \OC_User::userExists( $uid, $excludingBackend );
 	}
 	/**
 	 * @brief Loggs the user out including all the session data
 	 * Logout, destroys session
 	 */
 	public static function logout() {
-		\OC_USER::logout();
+		\OC_User::logout();
 	}
 
 	/**
@@ -107,7 +107,7 @@ class User {
 	 * Check if the password is correct without logging in the user
 	 */
 	public static function checkPassword( $uid, $password ) {
-		return \OC_USER::checkPassword( $uid, $password );
+		return \OC_User::checkPassword( $uid, $password );
 	}
 
 	/**
diff --git a/lib/public/util.php b/lib/public/util.php
index d69602f4507af9654c60cc54b95aeaae544fd284..7205950d149803c44c69d86f0e59f108ee845bf4 100644
--- a/lib/public/util.php
+++ b/lib/public/util.php
@@ -77,6 +77,15 @@ class Util {
 		\OC_LOG::write( $app, $message, $level );
 	}
 
+	/**
+	 * @brief get l10n object
+	 * @param string $app
+	 * @return OC_L10N
+	 */
+	public static function getL10N( $application ) {
+		\OC_L10N::get( $application );
+	}
+
 	/**
 	 * @brief add a css file
 	 * @param string $url