Apk copy/extracting/backing up protection
I hope that this is not the wrong place for my post.
I am trying to protect an apk from being copied/extracted/backed up off the phone and installed later, on another phone.
I have to mention that the app is not (and will not be) for sale on PlayStore or on any web store, being sold along with the phone. This is why I can not use apk protection offered by GooglePlay, which is anyway cracked at his time.
But I want to take advantages on this situation: every single phone will pass trough my hands (I will install myself the app) before hitting users. How can I use this advantage in order to protect my app?
At this time my app is not visible in Running Apps drawer, is having a default Android icon and the name is disguised in something pretty innocent. GUI access by dialing a code. No worries, is not malware but only a security app regarding GSM connection security.
Also, is running as a system app, which make it invisible for apps like Astro file manager, thus impossible to copy/back up by such file manager apps. Unfortunately there are a bunch of system app managers, that can convert a system app on user app, and then copying the apk file is easy.
I know that security sucks big time when it comes about Android OS, but I am determined to find a way to protect my app.
I know also that even a licensing scheme based on IMEI, WiFi MAC or Bluetooth MAC addresses can be bypassed by some skilled crackers. This values can be spoofed or even null.
I have tried apk encryption. Doesn't work: some apps supposed to encrypt other Android apps are actually encrypting only app libraries, not the apk file itself. By encrypting apk file, the app obviously will not work.
Code obfuscation is not an option as long the app can be duplicated off the phone and installed later on another phone.
The last idea that I had: pulling some app resources (like drawables) from a server. What do you think?
At this time I'm in a dead end. I have no more ideas how to protect my app. That's why I need your help. Can you give me please some feasible ideas, based on your huge experience?
Thank you very much for your time.