multibackend.py 文件源码

def create_cmac_ctx(self, algorithm):
        for b in self._filtered_backends(CMACBackend):
            try:
                return b.create_cmac_ctx(algorithm)
            except UnsupportedAlgorithm:
                pass
        raise UnsupportedAlgorithm("This backend does not support CMAC.",
                                   _Reasons.UNSUPPORTED_CIPHER)