I've been browsing around a bit learning about PS3 security in general (at a high level). From what I've gathered there's 2 things that are keeping newer games from running on 3.55:
1. They're encrypted with 3.56 public keys (which isn't really a problem since that's been leaked, so it's just a matter of decrypting the game and resigning).
2. They use functionality in the newer drivers (sprx files) that aren't present in older firmwares. It's my understanding that a few of the newer games that have been patched to work (Uncharted 3, Battlefield 3) do so because people have patched the game to work-around the new function calls, instead using the older ones. We can't just use the newer drivers present in the 3.56+ firmwares, since we don't have the keys to decrypt them, and they're signed for 3.56.
Anyways, here's my question. What would stop us from:
1. Decrypting the older 3.55 drivers and decompiling them with something like Boomerang to get a baseline (albeit ugly) C project.
2. Based on the leaked SDKs (which contain changelogs and stubs of the drivers) code in the missing functionality (at least what's relavent to games).
3. Recompile and resign the modified drivers for 3.55 and move them into a CFW.
I'm thinking I must be missing something or someone would have done this already, but I thought I'd throw this out here and see if someone could explain why this wouldn't work