I am trying do to some minor modifications (add a log line) to a third-party android application. However, the basic issue I am facing is that the application does not start, even when the only thing I do is resign package with
apksigner and my newly generated key. I have looked into both apks (original - working and modified - not working) and MANIFEST.MF is exactly the same and CERT.SF is almost the same (differs only in X-Created-By: header).
Any idea why the application might not start? Does the application have any chance to verify the apk signature after installation (some signature registry exists or META-INF are available for the app?) or does Android itself verify it in any way (what does it compare it with)? Or is it stripped after installation and I should look elsewhere?