Android: make a folder on external memory private or protected

Question

I want to make a folder on the external memory (could be on SD card) private or protected so that only my application/process can have access to that folder.

Can I do this? if so please let me know?

my requirement: I can use android's internal memory to store my app's files/data, but that may decrease the phone's internal memory (that can cause problems like not having enough space for other apps to install, etc)

Answer 1

Data on external storage cannot be private. It is world-readable and can be changed by the user if they enable USB mass storage.

Quoted from developer.android.com:

Every Android-compatible device supports a shared "external storage" that you can use to save files. This can be a removable storage media (such as an SD card) or an internal (non-removable) storage. Files saved to the external storage are world-readable and can be modified by the user when they enable USB mass storage to transfer files on a computer.