If it's reversible like that it is still possible for PayPal and others to implement it too.

Its encryption, you apply a transform before putting it onto the dropbox, and then you apply a transform after you pull it back, and the key it'd be encrypted against would be per user (like most encryption)

*major mode

Yeah, that reminds me of this company https://formygrips.com/

I don't think you should ever try, but you can give cygwin a shot. You can, supposedly, get most linux packages running on Windows with Cygwin, but it would be almost as much work as Linux From Scratch.

I don't think I can do this without source access to skype, unless I'm missing something?