My question is related to the repackaging of a mobile app. This app uses v1 signing scheme and I did the following:

I fetched the apk file from the playstore using adb and I signed with my keystore using apksigner. Now, when I launch this app on my smartphone, it is showing the following exception.

enter image description here

I took the original apk, I change the format to *.zip and unzipped it, and then again, converted back to apk and I applied zipalign on the apk. The apk gets successfully installed on the smartphone but when I launch this app, I am getting the following exception. enter image description here

In this scenario, I didn't modify any file. In the past, I have done this same process for few app's apk and the app is running successfully.

If you observe the above two exception's image, the 1st three lines are same.

My doubt is:

  • Irrespective of the signature change, we are getting the same exception (atleast the 1st three lines). What can be the reasons regarding the same? (Also, I have used the zipalign for the proper alignment)
  • Which type of framework this app is using such that even without changing the source code, the app is getting crashed?

Any help/inputs regarding this domain is highly appreciated.

  • The app seems to be obfuscated and may use invalid file names, therefore just unpacking and repackaging can already change the app. Make sure to unpack only on Linux as it has best support for abnormal file-names, is case-sensitive by default and has less restrictions regarding special file-names.
    – Robert
    Dec 15, 2020 at 12:56
  • Hi @Robert, I tried Linux also. But for that case, the apk generated file seems to be invalid. Hence the app won't even install. But when I used the WinRar Software on Windows OS, atleast, I am able to install. Dec 15, 2020 at 13:43


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