From what I understand, it is rather obscured then "encrypted". I'm not sure about Assembly but most higher level languages leave function and variable names in

From what I understand, it is rather obscured then "encrypted". I'm not sure about Assembly but most higher level languages leave function and variable names in the binary. There are many programs that rename the variables and function to something random so you will have a hard time what each function does. Mojang did that for their Minecraft game but developers soon found out what each method does and strated renaming them back to something useful – this is how Mod or Plugins are available. If apple did that with their kernel, then I'd say it is pretty bad security practice. A dedicated "hacker" can always understand what each function does with good confidence, it is just a pain in the neck and most volunteers don't wanna put up with that (while a state sponsored team may very well do that). Security through obscurity is always bad and only scares away people who could help while leaving many true bad actors with just more, painful work. If apple did indeed just obscured their kernel, I think apple did that intentionally to have people besides the FBI/NSA look at their code (they have been more and more concerned with security in recent years).