We get presented with the following challenge:

John bets nobody can find the passphrase to login!

GPG key: viphHowrirOmbugTudIbavMeuhacyet'

crack-me-if-you-can

 

The file extracts to an apk (Android package file). Running strings on it doesn't give us any insight into what's going on. Let's load it into Genymotion: