How can I protect my app from Google itself?

Question

I made a simple app that stores bank account, money transactions and other sensible data. Stored data is already encrypted, with no network access at all and closed to itself. But how can I make sure that other apps or the OS itself is not trying to read data the app generates? Are there trustable methods to see when and/or how my app is being tracked or read, even by the OS and log that "suspicious" activity?

I Tried to google that and read Developers manuals, but found nothing.

Answer 1

If you are saying that your data is

already encrypted

And not looking for a better encryption methods. Then you are basically asking a question not much different from: "Can I forbid for an OS an access to the screen buffer, and render my decrypted data directly on a hardware?"

The only totally safe solution to this problem is to create your own OS.

But then again... you must ask yourself: do you trust hardware manufacturers? Or that you hardware won't be somehow infected. https://www.symantec.com/connect/forums/bios-level-malware

Other options are:

1. Trust in open source.
2. Participate in open source and audit software you are using.
3. And there is always a security through obscurity: if you are not a millionaire bad guys won't bother wasting their time to break even a simplest protection.