'Returns standardized name for challenge certificate.
:param .KeyAuthorizationAnnotatedChallenge achall: Annotated
tls-sni-01 challenge.
:returns: certificate file name
:rtype: str'

def get_cert_path(self, achall):

    return os.path.join(self.configurator.config.work_dir, (achall.chall.encode('token') + '.crt'))
