This is a great and entertaining read about reverse engineering. It's such a good read that this is almost beside the point... but, as it happens, I worked on

This is a great and entertaining read about reverse engineering. It's such a good read that this is almost beside the point... but, as it happens, I worked on and reverse-engineered this same "encryption" scheme (I hesitate to use the word) for an iOS app that never shipped. I just dumped the code (which seems to have been written in late 2008) up on github... it's old, and messy, but hey, maybe it's fun for someone: https://github.com/davepeck/puzfile https://github.com/davepeck/puzfile