Hacking How do I downgrade a game's FW requirement?

[ikynx]

Hello,
I'm failing to find a tutorial / post here or elsewhere that explains how to proceed to:
1) assess if a game that has a high FW minimal version requirement (and therefore refuses to install using DBI on a lower firmware) can actually run on a lower FW version (in which case: what is that lower FW version it can run on without technically glitching)
2) patch the minimal FW version requirement for that game accordingly.

I've just come across City Hunter that just got released, that seems to be requiring FW 21.2.0, that I can't install using DBI because I'm on FW 20.5.0. I'd like to use this example as an exercise to learn on this topic.

Many thanks in advance

 

[AllOver]

It depends on the SDK version the game was built with.

There is a soft check for the minimum fw version in the cached cnmt, however most installers (should) set that to 0 by default as it doesn't modify the game content and only the cached data, which HOS only seems to check.

Once that check is passed, it tries to decrypt the game. It checks the keygen and if the key is available, it decrypts the game. A way around this is to decrypt the game and then encrypt it with a lower key (usually key0). This allows for the game to launched on all fw versions. However it will likely crash if using a sdk version that isn't supported on this fw.

With the above, some installers should be able to do this on the fly. DBI likely can, sphaira can, tinfoil can (or it used it). This option might be called "convert to standard crypto". It's called this way because it concerts title key (ticket) encrypted titles to "standard" ticketless crypto.

As this can be done on the fly, it's worth just trial and error and see what works.

 

[digdat0]

If you have SAK, you can load the NSP/XCI and choose the "Patch XCI" or "Patch NSP" option. You will then open the file, and it will patch the min FW requirement. I'm still on 19.0.1 and have had pretty good results for base game + updates which require 20.+, but some have failed. I think thats because those require a new SDK, which this tool (I dont think) can or does patch. I recall reading the a newer version of DBI was allowing patching the SDK requirement, but I've not seen a standalone app. I'm not 100% on the difference between FW version and SDK to be honest, so take this with a grain of salt

 

[ikynx]

thanks!

 

[Taffer]

thanks!

One game I tried all above listed solutions for was System Shock Remake and it wouldn't work until I updated to 20+