I would like to know what he used to write that coded message.

我想知道他用什么写下了那条密码信息。

Barbier pokes a series of holes into a sheet of a paper with his blade, creating a coded message that can be deciphered by fingertip, even in the pitch black.

Barbier 用他的刀片在一张纸上戳出一系列的洞，创造出一条可以用指尖破译的编码信息，即使是在漆黑的环境中。