class aes {         static public $mode = MCRYPT_MODE_NOFB;             static public function generateKey($length=32) {          if (!in_array($length,array(16,24,32)))              return False;             $str = '';          for ($i=0;$i<$length;$i++) {              $str .= chr(rand(33,126));          }             return $str;      }         static public function encrypt($data, $key) {             if (strlen($key) > 32 || !$key)              return trigger_error('key too large or key is empty.', E_USER_WARNING) && False;             $ivSize = mcrypt_get_iv_size(MCRYPT_RIJNDAEL_256, self::$mode);          $iv = mcrypt_create_iv($ivSize, (substr(PHP_OS,0,1) == 'W' ? MCRYPT_RAND : MCRYPT_DEV_URANDOM ));          $encryptedData = mcrypt_encrypt(MCRYPT_RIJNDAEL_256, $key, $data, self::$mode, $iv);          $encryptedData = $iv . $encryptedData;             return base64_encode($encryptedData);      }         static public function decrypt($data, $key) {             if (strlen($key) > 32 || !$key)              return trigger_error('key too large or key is empty.', E_USER_WARNING) && False;             $data = base64_decode($data);          if (!$data)              return False;             $ivSize = mcrypt_get_iv_size(MCRYPT_RIJNDAEL_256, self::$mode);          $iv = substr($data, 0, $ivSize);             $data = substr($data, $ivSize);             $decryptData = mcrypt_decrypt(MCRYPT_RIJNDAEL_256, $key, $data, self::$mode, $iv);             return $decryptData;      }}