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"How It Works" - Preventing Backups From Being Played

Discussion in 'PS2' started by duerra, Jan 17, 2007.

  1. duerra

    duerra Guest

    Hey all,
    I'm curious how the technology works that makes it so that consoles refuse (without mod chips) to play backup discs. Why can't a burner make an "exact" copy of exactly what it sees on the surface of the original disc? I don't understand how the encryption/protections/whatever work that prevent this from being a possibility. Couldn't a burner and/or burner software be developed that simulated some of the physical protections ("intentional unreadable sectors") or whatever other protections are put in place?
     
  2. steimy

    steimy Active member

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    That is a very good question indeed. I do not know the technology behind it, just that there is an area pressed into a disc called the BCA (Burst Cutting Area) that a DVD Burner can not copy.
     
  3. janrocks

    janrocks Guest

    Some of us know why and how..
    The original disks are printed, this info is contained in sector0 of the disk.. It's called a media check and is hard coded in the bios of the machine. There may be more than one, with the loading instructions containing a direct physical address, with a jump to instruction for any others. Looking at an unburned dvd disk will reveal a very fine ring near the centre hole.. This contains disk data..manufacturer, speed and disk type. The info that follows immediately is the where to go instruction, which pushes the hardware to the "user data" area..first thing it finds there is whether the disk is a dvd film, game, audio cd or data disk.
    Watching a laser on a console in operation gives another clue to how they do it.. Direct sector addressing, not menu based but rather to a certain position on the disk..then dither a little looking for the data start code. Look at a swap magic disk and you will see tracks, distinct data areas, and further investigating will show that the bootloader files are actually crazy taxi, which is also the media check printed on the disk.
    Now why we can't burn an exact copy..
    From the above it becomes obvious that we can't print disks at home without a major investment in hardware, the best we can hope for is to burn them.. Fail media check 1
    Then, because of the way most (yup most) burning software works we can only burn sequentially track afer track, in a sensible pc readable format..with no whitespace between tracks, which makes a nonsense of any direct sector addressing.. Fail media check 2
    It's perfectly possible to make an exact data copy of a disk..identical in every way except for the disk info, using some old disk copy tools like sector-burn or rawdump/cdrecord (early versions of CCcopy also.. It's how we used to make sega-megaCD disks, because there was no media check all the disk needed to be was an exact sector replica, but who could afford a burner in those far off days?) but as the disk info is still printed on the disk by the manufacturer we will always fail media check 1 unless we modify the hardware, or the bootloader software to defeat the disk check.
    It's an interesting subject, disk copy security and how it works. That's only a basic intro to it. There is quite a lot more to it, but that's all we really need to remember.
     
    Last edited by a moderator: Jan 18, 2007
  4. duerra

    duerra Guest

    janrocks,
    Thanks for the more in-depth analysis. Based on your response, it would still seem like it is technically possible to create an exact replica of a production disk, just that it would require slightly modified media, software, and hardware. Given the tremendous amount of public support out there that there would be for the ability to play backup media (or even, the demand for even black market media in general), I don't understand why we haven't seen appearances of this modified media and hardware (I would presume that the software is the easiest and/or already existing part of this equasion). While it would certainly cost a bit more, at the very least it would be profitable for at least a select few that were to exploit it. We have already seen hardware come to the market that takes much more complex design in order for users to be able to get backups of their software (any non-disc based gaming media in the past), so why haven't we seen this modified hardware for the latest generations of consoles???
     
  5. AngelusX

    AngelusX Member

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    Does that outer silver ring contain any data? It's all around the outer edge of the DVD. I'm hearing conflicting reports about it. Some say it has the data to determing if it's legal, some say it has the region check, and others say it's completely blank. Personally, I thought it was where the data ends and it's blank. Can you clear this up for me? It's bugging me for a while now.
     

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