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hugthebed2, posted Thu Jun 16, 2016 3:11 am (14503)

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Hi all, on steam there is a localized Japanese doujinishi game called 100% Orange Juice. The Steam version has many features that the original Japanese version does not. It is on PC and the store page for the game is here (there is also a demo available, which may use the same type of files).

The game's folder in the steam "common" folder has a folder with lots of data files all ending in .pak. The .pak files containing audio can be opened up with audacity or other sound software and are some sort of .ogg vorbis files.

The .pak files containing things other than audio can be extracted using file compressors like winRAR or 7zip, however the items extracted are just .dat files. That's where I've gotten stuck. I have no idea how to open these .dat files. I believe the game uses the Luna 3D Japanese engine, as stated in one of their blogposts (may refer to an old engine?).

Quote:

Tony: We also changed the texture format. Sora uses a Japanese engine called Luna3D, which is also used by our earlier title 100% Orange Juice. The engine handles a lot of things well, but its texture handling has problems. There's an issue with texture drawing that causes all textures to appear blurrier and the engine's own texture format is somewhat slow and also takes up a lot of space. We changed 100% Orange Juice's texture format some months ago and brought these changes to Sora as well. As result, our version should have faster load times despite having bigger images and the required hard drive space for textures is down to less than 100mb instead of the original's 1gb.

I have attached a few of the .dat files as well as the .paks that they reside in inside of a zip file. Any help would be appreciated, thank you.

As a side note, another game by the same company had its audio files investigated here, but I don't know if that would be of any help, as they may use different engines.

Ekey, posted Thu Jun 16, 2016 11:51 am (14510)

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*.PAK - simple ZIP
*.DAT - obfuscated / encrypted - seems xor

hugthebed2, posted Sun Jun 19, 2016 7:51 am (14602)

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Where do we go to next to try and decrypt the data?
I've gone through quite a bit of random programs with no luck in opening the files inside of the .pak files (the non-audio ones, at least).

Ekey, posted Sun Jun 19, 2016 8:14 am (14603)

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Debugging game, to find encryption algorithm