Ok, I've searched around a bit but I couldn't find much in terms of sonys encryption method for firmware files. I know that sony uses their own private 1024 bit key. I want to know : is it possible to encrypt prx files using the same METHOD as sony (the private key isn't important), and what is that method?
My logic is this (assume I'm using firmware 1.52):
1) Take a relatively small encrypted prx file from the flash (eg. usersystemlib.prx)
2) Using a PBP unpacker/prx decrypter get the decrypted usersystemlib.prx
3) Make a bruteforce program that encrypts the decrypted usersystemlib.prx, then compare it with the original one.
4) A match, and bingo.
I would have tried my hand already, but I couldn't find the encryption method sony uses. Instinct tells me that if it was that simple it would have already been done, but then I'm not that knowledgable when it comes to cryptogrophy. Are there any sites/books/etc about that would help?