def _encode_asn1_utf8_str(backend, string):
    """
    Create an ASN1_UTF8STRING from a Python unicode string.
    This object will be an ASN1_STRING with UTF8 type in OpenSSL and
    can be decoded with ASN1_STRING_to_UTF8.
    """
    s = backend._lib.ASN1_UTF8STRING_new()
    res = backend._lib.ASN1_STRING_set(
        s, string.encode("utf8"), len(string.encode("utf8"))
    )
    backend.openssl_assert(res == 1)
    return s