ROM Hack Question How to properly replace & resign edited save data to NAND

kimbra · Jun 9, 2019

Hello! I think I've made a lot of progress figuring out how to extract game save data from a NAND and inject it back to play on an OFW Switch, but I'm running into a hiccup. If anyone has any insight or can tell me exactly what I'm doing wrong, it would be wonderfully appreciated!

Here's my exact process step by step:

Use Lockpick payload to create prod.keys on microSD
Use Hekate payload to create boot & NAND backup on microSD
Insert microSD to PC and use HacDiskMount and corresponding appropriate keys to mount and explore the NAND User partition
Copy the game save I want to edit from the save folder within the NAND User partition
Place the save data file and prod.keys in my hactoolnet folder and create both a "sav" and "out" folder as well, then copy the save data file into the "sav" folder too

Create extract.bat in the hactoolnet folder:

Code:

hactoolnet.exe -k prod.keys
hactoolnet.exe -t save "sav/0000000000000019" --outdir "out/0000000000000019"

Run extract.bat and find the workable save data in the out/0000000000000019 folder (file is ffx_002)
Edit the save data (in this case FF10) with a save editor and save the changes to my hactoolnet folder
I now have the edited ffx_002 file, the original 0000000000000019 save data file from the NAND User partition, and an inject.bat in the hactoolnet folder as well:
Code:
```
hactoolnet.exe -k prod.keys
hactoolnet.exe -t save 0000000000000019 --replacefile /ffx_002 ffx_002
```
Running inject.bat replaces (and supposedly resigns) my edited ffx_002 save file within the original 0000000000000019 save data taken from the NAND User partition as both are in my hactoolnet folder
Copy the resulting edited 0000000000000019 save data file and, with HacDiskMount still running, explore to the NAND User partition save folder, and paste to replace the 0000000000000019 save data file with the edited one
Unmount the NAND User partition, remove the microSD card from PC, and restore the boots and resulting altered NAND to the OFW Switch using the Hekate payload again
Once completed, take out microSD and reboot Switch to run normally, attempt to play FF10 cart, loading ensues shortly followed by a black screen popup informing the save data has been corrupted with an offer to send a report to Nintendo (I just shut down the console and successfully restore the original boots and NAND at this point to fix)

So I believe I've done everything I need to in order to run edited saves on my OFW Switch, but I'm clearly missing something as it appears the edited save data isn't replacing & resigning correctly. As I said, I would be super appreciative of any insight or solutions anyone can offer. Thanks!

EDIT: Here is a list of resources I've been consulting throughout my trials:

NAND and boots backup tutorial: http://guide.sdsetup.com/gettingstarted/safetyprecautions
Info on save file extracting: https://gbatemp.net/threads/safest-...witch-to-a-hacked-switch.536619/#post-8603706
Info on key loading: https://gbatemp.net/threads/anyone-...data-extracting-pls-help.534451/#post-8568492
Info on extraction & injection process: https://gbatemp.net/threads/libhac-hactoolnet-v0-1-3.521599/#post-8431352
Info on signing save data: https://github.com/Thealexbarney/LibHac/issues/19
NAND and boots restore tutorial: https://nh-server.github.io/switch-guide/extras/nandrestore/
Info on key files: https://github.com/Thealexbarney/LibHac/blob/master/KEYS.md

masagrator · Jun 10, 2019

Easier wouldn't be:
1. Make nand backup
2. Use Checkpoint to load save
3. Make another nand backup
4. Copy folder with save from second backup to first backup
5. Write to nand first backup
?
Because I assume you want to avoid making crash reports on ofw.

kimbra · Jun 10, 2019

masagrator said:
Easier wouldn't be:
1. Make nand backup
2. Use Checkpoint to load save
3. Make another nand backup
4. Copy folder with save from second backup to first backup
5. Write to nand first backup
?
Because I assume you want to avoid making crash reports on ofw.

Interesting. What precautions would I take while running CFW for Checkpoint? I’d ultimately like to have no CFW run on my clean Switch whatsoever, but this appears to be a very difficult option. I feel like it’s possible to do from reading through this thread though: https://github.com/Thealexbarney/LibHac/issues/19

masagrator · Jun 10, 2019

Just turn on airplane mode before making first backup and turn it off after restoring first backup with modified save

bootmonster · Jun 11, 2019

kimbra said:
Hello! I think I've made a lot of progress figuring out how to extract game save data from a NAND and inject it back to play on an OFW Switch, but I'm running into a hiccup. If anyone has any insight or can tell me exactly what I'm doing wrong, it would be wonderfully appreciated!

Here's my exact process step by step:

Use Lockpick payload to create prod.keys on microSD

Use Hekate payload to create boot & NAND backup on microSD

Insert microSD to PC and use HacDiskMount and corresponding appropriate keys to mount and explore the NAND User partition

Copy the game save I want to edit from the save folder within the NAND User partition

Place the save data file and prod.keys in my hactoolnet folder and create both a "sav" and "out" folder as well, then copy the save data file into the "sav" folder too

Create extract.bat in the hactoolnet folder:

Code:

hactoolnet.exe -k prod.keys hactoolnet.exe -t save "sav/0000000000000019" --outdir "out/0000000000000019"

Run extract.bat and find the workable save data in the out/0000000000000019 folder (file is ffx_002)

Edit the save data (in this case FF10) with a save editor and save the changes to my hactoolnet folder

I now have the edited ffx_002 file, the original 0000000000000019 save data file from the NAND User partition, and an inject.bat in the hactoolnet folder as well:

Code:

hactoolnet.exe -k prod.keys hactoolnet.exe -t save 0000000000000019 --replacefile /ffx_002 ffx_002

Running inject.bat replaces (and supposedly resigns) my edited ffx_002 save file within the original 0000000000000019 save data taken from the NAND User partition as both are in my hactoolnet folder

Copy the resulting edited 0000000000000019 save data file and, with HacDiskMount still running, explore to the NAND User partition save folder, and paste to replace the 0000000000000019 save data file with the edited one

Unmount the NAND User partition, remove the microSD card from PC, and restore the boots and resulting altered NAND to the OFW Switch using the Hekate payload again

Once completed, take out microSD and reboot Switch to run normally, attempt to play FF10 cart, loading ensues shortly followed by a black screen popup informing the save data has been corrupted with an offer to send a report to Nintendo (I just shut down the console and successfully restore the original boots and NAND at this point to fix)

So I believe I've done everything I need to in order to run edited saves on my OFW Switch, but I'm clearly missing something as it appears the edited save data isn't replacing & resigning correctly. As I said, I would be super appreciative of any insight or solutions anyone can offer. Thanks!

EDIT: Here is a list of resources I've been consulting throughout my trials:

NAND and boots backup tutorial: http://guide.sdsetup.com/gettingstarted/safetyprecautions
Info on save file extracting: https://gbatemp.net/threads/safest-...witch-to-a-hacked-switch.536619/#post-8603706
Info on key loading: https://gbatemp.net/threads/anyone-...data-extracting-pls-help.534451/#post-8568492
Info on extraction & injection process: https://gbatemp.net/threads/libhac-hactoolnet-v0-1-3.521599/#post-8431352
Info on signing save data: https://github.com/Thealexbarney/LibHac/issues/19
NAND and boots restore tutorial: https://nh-server.github.io/switch-guide/extras/nandrestore/
Info on key files: https://github.com/Thealexbarney/LibHac/blob/master/KEYS.md

The thing you are doing wrong here is splitting the -k prod.keys on a separate line. You are essentially running the program twice the way you are doing it so how would it know what keys to apply when injecting the save?

Combine that into one line and your should be good.

ROM Hack Question How to properly replace & resign edited save data to NAND

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