base.py 文件源码

def decryptor(self):
        if isinstance(self.mode, modes.ModeWithAuthenticationTag):
            if self.mode.tag is None:
                raise ValueError(
                    "Authentication tag must be provided when decrypting."
                )
        ctx = self._backend.create_symmetric_decryption_ctx(
            self.algorithm, self.mode
        )
        return self._wrap_ctx(ctx, encrypt=False)