Question

I am downloading files from a remote server to be saved for use on an android device. These files are mostly images and audio but I would like it so that a user cannot access this data using methods other than the app.

The issue is that these files could be large and that’s why I use external storage. The problem here is that users can access the data stored on external storage by hooking the phone up to a computer.

Apart from using internal storage, do I have any options to secure the files written to disk?
If I do have to use internal storage, are there any other disadvantages other than the fact that some users might have a small amount of internal storage?

Thanks for your time! Any help will be much appreciated! 🙂

EDIT 1 :
The data being downloaded is paid content (via In App Billing). This is why I’m concerned about restricting access.

EDIT 2 :
I am already adding a “.” before the folder I’m saving my data to. I’m more concerned about ‘power’ users who would know to look in hidden folders.

Answer 1

Seems like you are populating app’s cache from web. It is always recommended to use external storage for such purposes because some users may not have enough internal memory to accommodate this.

Since you downloading includes images and audios, i wouldn’t suggest you to use encryption/decryption as it will slow down the app’s processing. So there’s nothing much you can do to secure your data if you want to put on external memory and skip its encryption.

I personally don’t think any harm/disadvantage to leave such data as it is (not encrypted). But if you have some of the files important, perhaps you may perform encryption on those particular files only.