Android Hacking Event 2017: Why Should I Pay?

[cTFk1ller]

How to solve this challenge: could you please give me a hint? I was able to get the key, which is "|yuiuiq|yyu.".
I think the problem should be related to Mac because Mac could be passed in a different way.

1. I used ghidra to reverse the function, but still nothing.
2. I also used Frida to hook the JNI_method, but still nothing.

Please provide some help.
The flag should be approximately "HE17{pr3mium4tiv4te}"