'Verifies the certificate presented at name is cert'

def certificate(self, cert, name, alt_host=None, port=443):

    if (alt_host is None):
        host = socket.gethostbyname(name)
    elif isinstance(alt_host, six.binary_type):
        host = alt_host
    else:
        host = alt_host.encode()
    name = (name if isinstance(name, six.binary_type) else name.encode())
    try:
        presented_cert = crypto_util.probe_sni(name, host, port)
    except acme_errors.Error as error:
        logger.exception(error)
        return False
    return (presented_cert.digest('sha256') == cert.digest('sha256'))
