Fix byte-safety issues & actually test for them
diff --git a/system/libraries/Encryption.php b/system/libraries/Encryption.php
index 74832ed..c1e454d 100644
--- a/system/libraries/Encryption.php
+++ b/system/libraries/Encryption.php
@@ -135,11 +135,11 @@
 	);
 
 	/**
-	 * mbstring.func_override flag
+	 * mbstring.func_overload flag
 	 *
 	 * @var	bool
 	 */
-	protected static $func_override;
+	protected static $func_overload;
 
 	// --------------------------------------------------------------------
 
@@ -161,7 +161,7 @@
 			show_error('Encryption: Unable to find an available encryption driver.');
 		}
 
-		isset(self::$func_override) OR self::$func_override = (extension_loaded('mbstring') && ini_get('mbstring.func_override'));
+		isset(self::$func_overload) OR self::$func_overload = (extension_loaded('mbstring') && ini_get('mbstring.func_overload'));
 		$this->initialize($params);
 
 		if ( ! isset($this->_key) && self::strlen($key = config_item('encryption_key')) > 0)
@@ -911,7 +911,7 @@
 	 */
 	protected static function strlen($str)
 	{
-		return (self::$func_override)
+		return (self::$func_overload)
 			? mb_strlen($str, '8bit')
 			: strlen($str);
 	}
@@ -928,7 +928,7 @@
 	 */
 	protected static function substr($str, $start, $length = NULL)
 	{
-		if (self::$func_override)
+		if (self::$func_overload)
 		{
 			// mb_substr($str, $start, null, '8bit') returns an empty
 			// string on PHP 5.3