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iPhone forensics expert Jonathan Zdziarski, who
recently released
the AMBER Alert for iPhone app, has a new app designed to help keep deleted data from being recovered from your iPhone. Called
iErase
, the app "zeros" all the free space on your iPhone and makes sure trashed files stay, well, trashed.
The iPhone, like most computing devices, doesn't actually remove files from you iPhone when you delete them. The bits are all there; the file system merely marks the space that the file was using as available. "The iPhone retains data better than most laptops because its solid state disk is designed to minimize writes," Zdziarski told Ars. "As a result, deleted photos, e-mail, keyboard caches, and other personal data are likely to stay on the device for a very long period of time. All of this information is available to someone who steals or 'borrows' our device."
He should know—Zdziarski has taught law enforcement agencies how to recover such data from iPhones seized as evidence. But, he says, "most of the trace data I teach about in my forensics course is also quite valuable to identity thieves or other malicious individuals. And if you've ever taken an embarrassing photo or exchanged confidential email, that's even more reason you want to make sure your free space is wiped periodically."
iErase is a simple application that can easily take care of this. It does so using the same technique as Mac OS X does when you "zero all free space" in Disk Utility—it creates a file made of just zeros as large as the free space on your iPhone or iPod touch. "Incidentally," added Zdziarski, "it's impossible for the app to delete anything because all it does is create a large temp file—it doesn't have code to actually delete any files, or permission to delete anything outside its sandbox."
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iErase's basically non-existent interface befits the simplicity of what it does. On launch, the user is presented with a warning about how the Auto-Lock setting can interrupt iErase's function, and then gives the option to cancel or continue. Also, the process can be cancelled at anytime by pressing the Home button. After changing my phone's Auto-Lock setting to "Never," I fired up iErase and hit the "Continue" button.
A simple progress bar shows how far along the zeroing process is, and gives a total of the space that's been zeroed so far. Fair warning: the process is slow—it took about 36 minutes to zero the 3GB of free space on my iPhone. For this reason, Zdziarski recommends having the device connected to a power source, though mine worked just fine with a full battery charge. Once finished, the app simply displays the text, "Operation Complete."
iErase is simple enough to use and does its job. If the security of your personal data is important to you—and Zdziarski believes it ought to be—then iErase is easily worth its $2 price tag.
Name:
iErase: Zero Free Space (
iTunes Link
)
Publisher:
Jonathan Zdziarski
Price:
$1.99
Platform:
iPhone and iPod touch
