multibackend.py 文件源码

def load_der_private_key(self, data, password):
        for b in self._filtered_backends(DERSerializationBackend):
            return b.load_der_private_key(data, password)

        raise UnsupportedAlgorithm(
            "This backend does not support this key serialization.",
            _Reasons.UNSUPPORTED_SERIALIZATION
        )