Hacking SHA-1/MD5 Verify wii game disc

[Tieracloud]

So long time didn't use our Wii physical games. Were just stored away. But now that the youngest one is of age to start playing I brought back out some of our wii games. And since it was kids mostly using them years ago the discs are not the healthiest looking. But to my shock they played fine. I even completed a lego game with bad scratches as she wanted to see the game progress.

However it got me thinking how in the heck did this game play all the way through. So what I did was this:

1) With Wiiflow installed the game to HDD
2) Ran a SHA-1 check with Wii backup manager and it failed saying not matched

From my understanding this means that since it failed the checksum that the disc I have is not a 1:1 copy and is missing data. But if data is missing due the scratches interfering is it strange that it works? Or does the disc have some sort of compensation that allows for scratches to exist over unreadable data and still play through?

Sorry for the novice questions but really didn't think of the technical side of how these games work.

 

[GreyWolf]

It's likely that wherever the corrupt data is you haven't hit it yet. As far as I know the SHA validation in WBM only checks the partitions, not the whole disc.

Wiimm's ISO Tools can give you better info as to what exactly is corrupt but I don't think the system area of the disc has a hash.