Re: libgpod and ipod touch 4g database checksum hash

Christophe Fergeau <[email protected]>
Newsgroups gmane.comp.ipod.gtkpod
Message-ID <[email protected]>
2011/1/2 Jim Doyle <[email protected]>:
> I'm not 100% sure I understand why changing the database version back
> helps.  Does it mean that the ipod doesn't bother checking a checksum
> when the older database version is in place?  Or does it mean it still
> uses a checksum, but the checksum is computed differently from the newer
> database version?

It means the latter, DBVersion 2 will make it use the same hashes as a
Nano 5g which we know how to compute.

> I think I see.  How does the ipod touch 3g work compared to the 4g?
> Does it also require computing a hash, but with a different hash
> algorithm?

Yes, the iTouch 3g has DBVersion 4. Basically there are 3 hashes,
DBVersion 3 used by the iPod Classic and Nano 3g+, DBVersion 4 used by
older iOS devices, and DBVersion 5 used by A4 iDevices. DBVersion 3
and 4 are known, DBVersion 5 isn't.

>  It must have been reverse engineered rather than released
> by Apple, right?
>

Yes

Christophe

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