Or mark the flash memory pages as clean making them available for future use, and leaving the data as is? I'm preparing my iPhone 4S for sale having upgraded to iPhone 5 and want to make sure the data is actually erased. If it is not, are there any apps that bit-erase the data? I used to SSH into my jali-broken iPhone 3 running iOS 3 and could see all the files. I have a nagging feeling that the new owner of the iPhone 4S could do the same by jail-breaking it, if the data still exist.