How to securely erase personal data from the iPhone
If you are looking to sell your iPhone, or give it to somone as a gift, you should probably ensure
that your personal data does not remain on the iPhone. Most would think that a restore via iTunes
would take care of this. But it does not! It has been proven more than once, and by more than one
person - one of them a programmer with deep routes in the iPhone community, and the other a state
police detective using a forensics data retrieval kit built by that same programmer - that your
personal data survives a restore. In the case of the detective, he purchased his iPhone via Apple
directly (refurbished). This entire process will take about an hour to complete, and your iPhone
will get a bit warm too, so don't be alarmed.
Launch the Settings application. Then press General, then Reset.
Press Erase All Content and Settings. Finally, press Erase iPhone. This will take approximately one
hour to complete, two hours if you have a 32 GB iPhone. You should probably have the iPhone plugged
in while it does this if you are low on battery power.
You will be prompted one final time, to confirm you wish to do this. You will then see this screen
for the remainder of the process.
Should your iPhone become stuck at the Apple boot logo (or your custom boot logo, remember you
haven't restored the firmware), and you see the small spinning wheel also freeze, then what you need
to do is press and hold the Sleep/Wake button and the Home button until the phone shuts off. This
will identify itself when a thin colored line appears at the top of the screen and then the whole
screen goes black. Hold the Home button, and plug it in via USB to your Mac and iTunes will
identify the iPhone as being in recovery mode. Now just press the option key on your Mac and click
the restore button and select whatever firmware you'd like to put back on the iPhone.