Rockbox Development > New Ports
Creative Zen Vision:M
saratoga:
--- Quote from: iSE on March 30, 2007, 05:53:40 PM ---A hash by using an algorithm then?
--- End quote ---
A hash is just a number produced by an algorithm, so yes.
--- Quote from: iSE on March 30, 2007, 05:53:40 PM ---I was meaning by using it size and properties to calculate a checksum, by updating the file the checksum would change however.
--- End quote ---
Generally checksums are computed using the contents of a file, not its size (since size is already just a number, which would make creating a checksum from it pointless), but otherwise, this is also what I meant.
--- Quote from: iSE on March 30, 2007, 05:53:40 PM --- So how to Creative get the firmware to pass then which otherways can't?
--- End quote ---
The most obvious way is to compute the hash, and then store it in the header of the file. Then the bootloader or firmware update program can simply read off the expected hash, and then compute the hash over the rest of the file. If the computed and read hashes match, then you know the file has not been tampered with. If we knew where the hash was stored, and how it was generated, we could also produce our own firmware updates.
Now, its not clear to me how this works, but it seems people in the above thread determined that the firmware update utility itself does a hash check. The bootloader may or may not, but if it does, hopefully its the same one as the update utility. So one way to proceed would be to look at the update utility and see if theres any clues in it as to how the hash is made. At least thats my understanding from reading the various stuff posted here ( I don't have a Creative player).
--- Quote from: iSE on March 30, 2007, 05:53:40 PM --- Would simply replacing the file on the HD cause an abort when switching it on then?
--- End quote ---
On the Sansa and many other players, this is exactly what happens.
iSE:
So once we have a new firmware we have to convince the player that its legit by getting it to pass the same checksum tests which the legit version would. I don't suppose we could just ring up Creative and ask?
saratoga:
--- Quote from: iSE on March 30, 2007, 06:18:58 PM ---So once we have a new firmware we have to convince the player that its legit by getting it to pass the same checksum tests which the legit version would. I don't suppose we could just ring up Creative and ask?
--- End quote ---
Check page 4 or 5 of this thread.
iSE:
Ok I've read everything now, there seems to be a lot of things starting and very little finishing. If money is a problem, I will be willing to donate some for this cause as I've already spent a fortune on this player, I'd be willing to pay some more to get it to work well!
I have already tried posting in the creative forums, no one seems to help, I'll try emailing and nagging creative until they give me a response worthwhile. If anyone can tell me how I can safely take apart my Zen to gain direct access to the harddrive I will give it a go. In the meanwhile I'm going to do what I can to dissect the update program and continue to try to force mount the zen. If only I knew what filesystem it supported it would be so much easier to gain access to it.
jhulst:
--- Quote from: iSE on March 30, 2007, 07:44:03 PM ---I have already tried posting in the creative forums, no one seems to help, I'll try emailing and nagging creative until they give me a response worthwhile.
--- End quote ---
The most worthwhile response I got was where they told me to go buy a different player if I wasn't happy with what I had.
As for the test machine, I got it, took it apart, and am now trying to figure out what kind of an adapter is needed for the harddrive and how it would hook up. I'll post pictures when I get a chance. It seems that there are two different hard drives. A Toshiba and a Hitachi. The Toshiba seems to have an IDE interface, the Hitachi we think is ZIF but are having a hard time getting the ribbon detached.
jwh
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