Recently we created a small Android challenge that we’d like to share with you guys. The goal is simple: you’re given an .apk file and you have to find out for which input (valid inputs are nonnegative integers smaller than 2^64) the app generates 0x63616c7978723078 (“calyxr0x”). The APK file is available for download here: calyxr0x.
Hope you have fun solving it! Let us know at email@example.com about your approach. Don’t hesitate to attach the resume as well if you’re interested in job opportunities. 🙂