[PKG Format] Game Archive Research

I’d like to use this thread for discussion and research of the game’s .pkg file format. Feel free to post any information you find and I will update the OP with highlights.

One thing I’ve found so far is that the pkg files are RSA signed (SHA256 RSA signature) and part of what is signed contains hashes of the data in the file. From what I can tell, the file entries are hashed along with some other information about the pkg, all of the file entries also contain an SHA-1 of the data, so no ISO modification.