storage.py 文件源码

def encode_block(self, block_id, block_data):
        assert (isinstance(block_id, bytes)
                and len(block_id) == self.block_id_len)
        enc = Encoder()
        enc.encode_bytes(self.magic)
        iv = os.urandom(self.iv_len)
        enc.encode_bytes(iv)
        c = Cipher(algorithms.AES(self.key), modes.GCM(iv),
                   backend=self.backend)
        e = c.encryptor()
        e.authenticate_additional_data(block_id)
        s = e.update(block_data) + e.finalize()
        assert len(e.tag) == self.tag_len
        enc.encode_bytes(e.tag)
        enc.encode_bytes(s)
        return enc.value