def get_signing_key(self, algorithm, service_context):
        """
        Pick signing key based on signing algorithm to be used

        :param algorithm: Signing algorithm
        :param service_context: A
            :py:class:`oidcservice.service_context.ServiceContext` instance
        :return: A key
        """
        return service_context.keyjar.get_signing_key(
            alg2keytype(algorithm), alg=algorithm)