*tl;dr: each stage constructs a part of the flag* [full writeup here](https://blackbeard666.github.io/pwn_exhibit/content/2020_CTF/RaziCTF/android_lock/lock_writeup.html) (https://blackbeard666.github.io/pwn_exhibit/content/2020_CTF/RaziCTF/android_lock/lock_writeup.html)