iphone - Protecting the app sandbox

Question

So I am working on a test app that downloads files locally to the app file storage sandbox. Some of these files may be sensitive and need to be protected. My app has a login mechanism, so you wouldn't be able to access the files if you didn't have a login, so my main concern is the ability to sniff the contents (Perhaps on a jailbroken device??).

Now I was wondering if the best method to protecting these files is to encrypt each one independently? Or perhaps there is a way to encrypt the whole sandbox? Or is it encrypted by default? Has anyone ever done anything like this before?

I apologize for the long string of questions, I am trying to gather as much info about this as possible before making a design decision...

Thanks!

Answer 1

You might want to look into the File Protection mechanisms in iOS 4 and later. That provides a way to mark a file as "protected" so it will be stored encrypted on disk at all times, only accessible when the device is unlocked (with a passcode).

See also this question