I'm trying to extract asset from this mobile game run on cocos2d for archival purposes, but completely stumbled upon these texture files. The file extension is .astc which is a graphic file format. But upon inspecting the file with hex editor the only thing i can find is that they have a fixed 15-byte sequence (47 76 52 67 62 75 4B 66 5A 33 38 A1 4A 51) at the beginning of the file and it does not match astc specification so i assume they are encrypted. Does anyone face similar case before and is there a suggested route to take to actually read these files? I would prefer static analysis approach but any help is appreciate. sample files are attached to this post so you can check it out.
About the game, its name is パズルガールズ and its package name is jp.spacegirl.fleet
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