Gamecube DVDs



hi friends, just to keep you up to date on stuff you might not have been hacking around yourself with:

Gamecube disks are more or less standart dvds with some twists:

  • they use a bca
  • the sector layout is a bit different. user data starts at offset 6 in the raw sector, where normally you’d expect CPR_MAJ
  • the dmi contains “Nintendo Game Disk”

also tmbinc and i have started a wiki documenting the original firmware here:

cheers, bc


hmm seems i cannot edit my post anymore :confused:
i almost forgot the most important thing: they use custom seeds for the scrambling…


@blackcheck, you can edit your post 30 minutes after you’ve posted it, after 30 minutes it’s closed for editing. :iagree:


well yes i figured out that one, i just wanted to make the point that it sucks :iagree:
anyway its arguable and i could live with that. however the way you turn my post into one ugly advertisement is probably not making me come back here again (big loss yeh :p)
and yes i know i can log in to avoid that, but i dont see why i should have to.

i understand that cdfreaks somehow needs to make money to run, but this has simply gone beyond good taste for me.

cheers, bc


Totally agree with you. :iagree:

Advertisement? Sorry, but I don’t understand what you mean. :confused:
The 30 minutes rule ain’t coming from me. :disagree: I have zero influence overhere. :slight_smile:

Again, I don’t know what you’re referring too?
What has my post to do with how CDFreaks makes money??


hehe sorry, of course i wasnt blaming you for the advertisement thingy. maybe that formulation was a bit misleading. just try and read some threads without logging in, thats what im talking about. not your fault for sure :slight_smile:

hehe if i just could edit that post, i’d replace “you” with “cdfreaks” :stuck_out_tongue:
sorry for the confusion


Interesting. This is the only system that I have ignored, I will go and buy one today and some discs - it is intriguing, but makes sense, I guess!

Changing the scramble table IV’s would make a very simple, yet effective (against most people) mechanism for cheap “encryption”.

I’ll see what I can discover about the discs over this weekend, I have some time to spare… :wink:


These discs are intriguing.

I was only able to procure a single GameCube game (I couldn’t find any units near where I live) but examination of the 8cm disc is interesting.

From my brief investigation, it appears that the seed IV’s are stored in a descriptor in the Lead-In @ 0x02f300 and further mutated by a salt (my best guess, without the unit itself to cross check) is that the salt is simply extrapolated from the BCA.

I will get a unit sometime next week and have a closer look into the drive unit itself to confirm my suppositions.



Replication of the disc was trivial - no real challenge there. The only “issue” is with the salt value being in the BCA.

I have a theory to counter that though, but not the time to waste on it. An exercise for those intersted would be to simply re-encode the image so that the scrambling vectors are based (instead) with a salt of 0 (that is, no BCA).

I would have expected something more from Matsushita…