Hacking Questions about headers and save games

[paulie]

I have some questions about the issues that arise from using .3dz files and save games.
What exactly is it that makes save games from "headerless" roms incompatible with .3dz roms that do have a header?

If I understand correctly, "headerless" simply means that the header is empty/contains only 0's.
Is this correct?

Does the save incompatibility issue arise due to the save file referring to the specific header, or is it encrypted by the header in some way?
Does this issue only arise when the .3ds extension is changed to .3dz? AKA if I use a rom with header, but leave it as .3ds, would the save file still work on headerless roms?
Would a .3dz save file from a rom with header work on a .3ds rom without header?
Would the header be extractable from the save file?

I am asking all this because I am worried that uploading save files from my legit rom dumps could lead to me sharing my header with basically anyone that gets ahold of the save file.


Any help and clarification on these issues is greatly appreciated!

 

[Huntereb]

What exactly is it that makes save games from "headerless" roms incompatible with .3dz roms that do have a header?

Haven't looked into it, but it's probably a security feature used by Nintendo to make sharing saves impossible. It compares the header in the encrypted save with the header on the game. If they don't match, it flags it as corrupted.

If I understand correctly, "headerless" simply means that the header is empty/contains only 0's.
Is this correct?

It's all F's, but yes.

Does the save incompatibility issue arise due to the save file referring to the specific header, or is it encrypted by the header in some way?
Does this issue only arise when the .3ds extension is changed to .3dz? AKA if I use a rom with header, but leave it as .3ds, would the save file still work on headerless roms?
Would a .3dz save file from a rom with header work on a .3ds rom without header?

If a save file was created on a legitimate header, and you tried to use it on a dump with a blank header, it would not load the save. Reason being what I said in the first answer.

Would the header be extractable from the save file?

There is no public way to decrypt saves... Yet.

I am asking all this because I am worried that uploading save files from my legit rom dumps could lead to me sharing my header with basically anyone that gets ahold of the save file.

If you created the save using your own dump, there's no point in releasing it here. You'd have to give your header out for people to use it. Once decrypting saves is possible, we'll likely have access to your header. Can't right now, though.

 

[paulie]

Ok thanks, that clarified all I wanted to know!