[https://infosec.rm-it.de/2017/06/19/google-ctf-2017-mindreader/](https://infosec.rm-it.de/2017/06/19/google-ctf-2017-mindreader/)

Original writeup (https://infosec.rm-it.de/2017/06/19/google-ctf-2017-mindreader/).