GMK File Format Cracked

Scorptek has confirmed that hackers have been busy cracking the key to unlocking Game Maker 7’s infamous file format, GMK.

Not only can GMK files be decrypted, but they can also be converted to the older more familiar GM6 format.

IsmAvatar has provided full documentation on the inner workings of the GMK file here.

A basic GMK converter can be found on this forum post on the G-Java website.

Basically this means there is full backwards/forwards computability between the two versions now, and any of the following can be accomplished:
– Publishing a game in GM6 and GM7
– Converting a project file from GM6 to GM7
– Converting a project file from GM7 to GM6
– Converting a GM6 executable to “GM7 executable” (Vista compatibility)


22 Responses

  1. How “complete” is it, will it work 100% everytime?

  2. Let’s see how YoYo will react to this new development.

  3. Let’s see how YoYo will react to this new development.
    Read the file from IsmAvatar

  4. Me thinks GM6 users are gonna like this 😛

  5. By the way, the unthinkable happened: YoYo updated their blog.

  6. Now *this* is news! I knew it was only a matter of time…

  7. Good work ISMAvatar. I agree with celebraces.

  8. is this out for download? if so whats the link? how will this affect the future?

    exactly my point. i think that so people arent able to unwise an executable unless they know the game id. the only problem is that using gm’s default gamesave action includes this in the filename. but there are ways to easily force-change the games id and stuff but i think that the future of gm will be chaos because people will download this and want to hack hackitty hack-hack-hack

  9. umm… not really. the same stuff was known for the gm6 (and probably gmd, I’m not sure) formats. it wasn’t chaos then, so it probably won’t be now. besides, what would they want to hack?

  10. not really, mark himself has told me that you can’t convert a gm exe back to editable- I accidentally overwrote the source to one of my games and he couldn’t help me.

  11. Probably because if there was a way to get it back, he didn’t want word of it going around. If other people found out he could undo .exe files, people would spam him with stupid questions like “can i maek Internet explorr into a gm??” and “How I get this progarm? :o” and other annoying questions. Plus it would spark a huge wave of hacking EXEs.

    I don’t really care if there’s a way to undo .EXEs or not, I’m just glad .gmk files can go back to .gm6. I accidentally ported many of my projects to it once.

  12. There are 3 parts to this, and you only seem to have 2 of them.

    1) GMK is encrypted. The scheme was fairly simple and was cracked by Quadduc, who then created a python script to do so. From this script, I learned the scheme and documented it in layman’s terms. That documentation can be found here:

    2) Once decrypted, the resulting data follows the basic format that you already linked:

    3) Once the data is read in to variables and such in a supporting IDE such as LateralGM, you may then re-save it as a GM6 file, discarding exclusively latter data and defaulting exclusively prior data (that is, anything specific to GM7 goes away, and anything specific to GM6 is substituted with default values). This is available as of LGM 1.6. As of this post, LGM 1.6 has no stable release, and must either be downloaded from the SVN or from G-Creator’s premature release of LGM 1.6 in their forum topic:

    As for hacking EXE’s, the LGM team will do everything in its power to prevent any such methods from reaching the public, in order to prevent it from being used for obvious malice and to prevent mass panic. We’ve also encouraged the G-Creator/G-Java team to do the same. If we were to have the technology, we would be sure to only use it if it complies with legality/licenses, and only for good purposes with the full consent of the game author. I can assure you that the three links/parts I’ve given above are entirely insufficient to hacking exes, thus your exes are safe in that respect.
    The technology Josh @ Dreamland uses is entirely different, and not affiliated with LGM in any way. Knowing him, he will use what he knows only for good, to further help protect exes from exploitation.

    At this time, I have no further comments, except to say that if you have not already, please support GameMaker, Mark Overmars, and YoYoGames, through donations and likewise, to help further development. From what I’ve heard, they have some very promising changes that may eliminate/alleviate the need for third party software such as LateralGM and the late G-Java.

    (For this and other LateralGM breakthroughs, formats, and projects, please visit our forum at )
    -IsmAvatar, cmagicj at nni dot com

  13. yeh, anyway. Bit late i guess ^^

    I found out the EXE can NOT be converted back to gmk or gm6…BUT! Scripts sprites and sounds can be extracted from it =\

  14. yes it can

  15. I love that word, “technology.”

    That was before it was realized you could take apart GM, at least a lot of it, with a hex editor, and a bit of GML. Which is <_<.

  16. Hi! rather righteous labour!
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  17. Well, IsmAvatar, you sound like a weapon constructor for me…

    “I only created the gun, but I did not shot with it! It meant for keeping peace… I never thought that it could have been put onto bad use…”

    Bullshit, simply…

  18. Hello webmaster
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  19. hello everybody ;
    there is no a converter to convert THE exes made with GM7 to the editable version because i need this to convert my Game to the GM7 file , I have lost my GM7 file .
    thanks .wait answers

  20. Perhaps back then we still had a memory of a better time to keep us hoping that it would come around again, sometime. ,

  21. This is surely one of the most elementary characteristics of the human rhythmic response, and one that is displayed spontaneously by young children. ,

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