Cave Story DSiWare checksum fix

So I was just messing around Cave Story DSiWare just doing my usual shenanigans and I found myself save editing for one reason or another, only to be greeted with this.

Confused, I made two new save files and diffed the two of them, and sure enough, they were indeed checksum'd. Sidenote this has to be like the only version I'm aware of that has this kind of protection, wack.

So I pulled up Ghidra and No$GBA, only to find out that it was just calculating the CRC-32 of a 0x800 block, minus the checksum obviously.

So anyway I wrote a simple python script to fix it, and sure enough it worked.

 

im no tech nerd to understand what this is, but i will say it's honestly really cool how we're still discovering stuff about the game after so long. good find! can't wait for andwhy to add this discovery/fix to the site.

 

im no tech nerd to understand what this is, but i will say it's honestly really cool how we're still discovering stuff about the game after so long. good find! can't wait for andwhy to add this discovery/fix to the site.

To put it simply the game checks if the save file has been tampered with and refuses to load it if it sees that it has been.

 

did nicalis foresee people tampering with save data? why add this protection only to this version of the game? i understand if there was a competitive challenge mode or something, but i dont think there should be any need to prohibit save modification for a game like cs where it's just you playing on your own for fun.