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Xbox Sphinx Protocol

October 20th, 2013 by Multimedia Mike

I’ve gone down the rabbit hole of trying to read the Xbox DVD drive from Linux. Honestly, I’m trying to remember why I even care at this point. Perhaps it’s just my metagame of trying to understand how games and related technologies operate. In my last post of the matter, I determined that it is possible to hook an Xbox drive up to a PC using a standard 40-pin IDE interface and read data sectors. However, I learned that just because the Xbox optical drive is reading an Xbox disc, that doesn’t mean it’s just going to read the sectors in response to a host request.

Oh goodness, no. The drive is going to make the host work for those sectors.

To help understand the concept of locked/unlocked sectors on an Xbox disc, I offer this simplistic diagram:


Xbox locked disc diagram

Any DVD drive (including the Xbox drive) is free to read those first 6992 sectors (about 14 MB of data) which just contain a short DVD video asking the user to insert the disc into a proper Xbox console. Reading the remaining sectors involves performing a sequence of SCSI commands that I have taken to calling the “Sphinx Protocol” for reasons I will explain later in this post.

References
Doing a little Googling after my last post on the matter produced this site hosting deep, technical Xbox information. It even has a page about exactly what I am trying to achieve: Use an Xbox DVD Drive in Your PC. The page provides a tool named dvdunlocker written by “The Specialist” to perform the necessary unlocking. The archive includes a compiled Windows binary as well as its source code. The source code is written in Delphi Pascal and leverages Windows SCSI APIs. Still, it is well commented and provides a roadmap, which I will try to describe in this post.

Sphinx Protocol
Here is a rough flowchart of the steps that are (probably) involved in the unlocking of those remaining sectors. I reverse engineered this based on the Pascal tool described in the previous section. Disclaimer: at the time of this writing, I haven’t tested all of the steps due to some Linux kernel problems, described later.

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