def _get_cn_cert():
    """Get the public TLS/SSL X.509 certificate from the root CN of the DataONE
    environment. The certificate is used for validating the signature of the JWTs.

    If certificate retrieval fails, a new attempt to retrieve the certificate
    is performed after the cache expires (settings.CACHES.default.TIMEOUT).

    If successful, returns a cryptography.Certificate().

    """
    try:
        cert_obj = django.core.cache.cache.cn_cert_obj
        d1_common.cert.x509.log_cert_info(
            logging.debug, 'Using cached CN cert for JWT validation', cert_obj
        )
        return cert_obj
    except AttributeError:
        cn_cert_obj = _download_and_decode_cn_cert()
        django.core.cache.cache.cn_cert_obj = cn_cert_obj
        return cn_cert_obj
Get the public TLS/SSL X.509 certificate from the root CN of the DataONE
    environment. The certificate is used for validating the signature of the JWTs.

    If certificate retrieval fails, a new attempt to retrieve the certificate
    is performed after the cache expires (settings.CACHES.default.TIMEOUT).

    If successful, returns a cryptography.Certificate().