Job well done! I tried reverse engineering the encryption on Yamaha's midi files. I thought it would be super complex but it turned out to be ridiculously easy. It's funny when you're preparing mentally for some long slog and turns out to be an hour at best. In case you're interested: they used a fixed block of 256 bytes that they xor'd the data with in a cyclic fashion.
Another day another hardware manufacturer rolling their own encryption. We are lucky these companies don't really know what they are doing or they could actually make it close to impossible to hack the firmware.
Ham radio is well worth getting into if you come from a software background but want to get more hands-on with embedded electronics. Radios are ubiquitous in modern technology, and getting a deeper understanding of how they work can have surprising career benefits too!