How does Game Jackal work under the covers?

Discussion in 'GameJackal' started by nrnoble, Jul 11, 2007.

  1. nrnoble

    nrnoble Member

    I understand what it does for me, allows me to run games without having to insert the game CD, and I know it doesn't create copies of games CD.

    I am simply curious as to how it works so that most games think that the game CD is in the drive. My guess is that GJ is monitoring the IO APIs while the game is playing, but I sure it is more than that.

    If this has been asked and answered in another thread, point me in the right direction.

  2. evlncrn8

    evlncrn8 Well-Known Member

    yup, monitoring the communications... filter driver style...
  3. mad_fr34k

    mad_fr34k Well-Known Member

    something tells me that they arnt going to tell you how it works under the bonnet, you might be a developer trying to make your own product :D
  4. evlncrn8

    evlncrn8 Well-Known Member

    well if he was he could just throw maplom.sys into a disassembler and work from there couldnt he
  5. Mr. Vage

    Mr. Vage New Member

    My best guess is that both Game Jackal and AnyDVD insert themselves between the drive and the program. Game Jackal's version dialog has a driver version, so it's possible that it replaces the disc drive's driver with it's own. That would mean that all of the I/O operations would go through Game Jackal. Game Jackal could then choose to send whatever data it wants back and the game would think that the data is coming from the CD when, in fact, the drive never even spun.
  6. evlncrn8

    evlncrn8 Well-Known Member

    erm, and that is a filter driver to all extents and purposes...
  7. nrnoble

    nrnoble Member

    Thanks for the info. Yeah, I wasn't expecting them to send me the code so I could spend the next 10 years trying to figure it out. I was just curious about the high level stuff. :)
  8. Targon

    Targon Well-Known Member

    The best way to explain is to cover the basics of how a profile is made, and that may help.

    In Game Jackal, you tell it you want to create a new profile. The normal behavior is for the CD/DVD to NOT be in the drive at the time. So, you are then prompted to either use a pre-created profile, or let Game Jackal do everything automatically.

    Now, it prompts you to insert the CD/DVD, and then the game launches when you insert the game disc(based on the profile or what file you told it to run in profile creation). The game launches, and you then exit quickly(once you are in far enough for the copy protection to have been activated).

    During that process, Game Jackal has been monitoring the CD/DVD drive activity, so it can see what sectors are being scanned by the copy protection. At that point, the details are not known, just which sectors are being checked.

    On exiting the game, Game Jackal now goes to work doing an analysis of the sectors accessed when the game was launched. That analysis goes into the profile so that they can be emulated when the profile is active.

    Once the analysis is done and the information captured, Game Jackal now knows how to respond when the game checks for the game disc. It's as simple as that(on the surface).

    Now, there are some copy protection methods that check different sectors based on the day of the month, so for SOME games, you need to update the profile to add the missing sector information. This is why you get SOME games where it works, but not all the time. If the game profile works sometimes, but not others, it indicates that the game in question checks different sectors each time you run the game. This is why the pre-made game profiles are useful, because they will include a list of sectors to add to the profile.

    Note that at this point, Tages protection(used on The Witcher and a few other games) is not supported by Game Jackal, though it has been indicated that it is on the list to be worked on this year. Tages is probably the most successful copy protection at this point because it is not used by many games(perhaps 5 or so), but with the popularity of The Witcher, there is more pressure to have Game Jackal and other applications deal with it properly.
  9. evlncrn8

    evlncrn8 Well-Known Member

    how's tagés the most successful when..

    1. its used on considerably less titles than say for example safedisc, starforce or securom
    2. its emulatable by daemon tools
    3. its cracked quickly too

    the only thing that sets it apart is the fact it can't be easily physically burned due to the duplicate sector thing
  10. Targon

    Targon Well-Known Member

    I didn't say it was the most secure, just that because it isn't used extensively, there are relatively few programs that will emulate it. Anything can be cracked quickly, and there is NOTHING out there that can't be cracked these days.
  11. evlncrn8

    evlncrn8 Well-Known Member

    nope, you said it was the "most successful... ".. im asking you how you came to that conclusion...
  12. Blazkowicz

    Blazkowicz Well-Known Member

    Regarding cracked quickly:

    Just look at Daemon Tools Pro, 3 latest versions uncracked.