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So, for the last few days, I've been working on this problem. I've been trying to gain access to an Android app's code, and have managed to narrow it down (probably) to the app's .OBB file. I can open the .OBB file just fine using 7zip. It has 4 files that I can recognize, 3 images and an audio file, with a 5th file that contains nothing and has a random name to it. Then, there is a bin directory leading to a .Data directory, which then contains the majority of the game files in formats that I don't understand. Most of the information stored in the files is a garbled mess, but some of the files have legible names, some of them are .resource files, and a few are of other types like .split<#>. Is there any way for me to deobfuscate these files into something legible? Are they encrypted somehow? If they are usable by the application in this form, is there some kind of translation or decryption going on within the phone between the APK and the OBB, in order to allow them to become usable? Could I take advantage of this translation to gain access to legible files? One of the last leads that I have to work off of is the Android Studio JOBB program, which seems to be involved in extracting information from OBB files. But when I try to use that one, I get a statement about how the OBB footer didn't match the magic string, which seems to be a certain string that a file uses to identify itself as an OBB file. Any help would be appreciated. Here is a link to a previous question where I was trying to work out this problem.

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  • I am not an OBB/game expert but I if there is a protection than it is game specific. Have you tried to identify the unknown files using Linux file command`. If that does not help you have to reverse engineer the app and check where and how it load those files. If you are lucky the game is implemented in Java/Dex code so you can use Jadx. If not you have to decompile the so files using Ghidra/IDAPro/JEB ...
    – Robert
    Jan 21 at 12:17

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