Android. ERROR_COULD_NOT_MOUNT while mounting complex ciphered obb file

Question

I develop Android app, which uses ciphered obb file. This obb file consists of 3 files (I created it with jobb tool). On the most devices all is ok, but on the three devices the

Answer 1

So, after all my investigations I can say. All I can to do is workaround. And I have created one file from the these 3 files by

copy /B file1+file2+file3 result_file.obb

And then I use this file as non-ciphered obb. After all this manipulations all works well.

Answer 2

I find the reason for some obb file could not be mounted. There a random solt when make obb file, an hashkey generated by PBKDF2WithHmacSHA1. the hashkey from bytes convert to hex string has a bug. I submit a patch to project : platform/framwork/base.

https://android-review.googlesource.com/#/c/230280/

I modified the jobb tool. Add check the hashkey to skip the wrong key generated. Before the Android merge the patch, you can use this patch. This patch also fix the dump files bug.

https://android-review.googlesource.com/#/c/231431/