'Return the DER encoding of this name
:return: A :py:class:`bytes` instance giving the DER encoded form of
this name.'

def der(self):

    result_buffer = _ffi.new('unsigned    char**')
    encode_result = _lib.i2d_X509_NAME(self._name, result_buffer)
    if (encode_result < 0):
        _raise_current_error()
    string_result = _ffi.buffer(result_buffer[0], encode_result)[:]
    _lib.OPENSSL_free(result_buffer[0])
    return string_result
