Well, this is unsettling. Avast, the anti-virus app makers, released a report that Android’s factory reset abilities don’t actually delete your data.
The handy infographic related to the research is all a part of a marketing ploy on Avast’s part to hawk its product, but it’s also a worthy reminder that when you sell or give up your phone, you’re actually giving up a little piece of your digital self.
Most users will feel like Android’s built-in factory reset is enough, but it’s not. When you delete data on most digital devices, Android phones and tablets included, you don't really get rid of all those 1s and 0s. Rather, you simply tell the file system "this data is safe to write over with other stuff." To do otherwise would be slow, and shorten the lifespan of your flash storage.
If you have particularly sensitive information living on your hardware or you just want a little extra peace of mind, here’s a helpful tip on keeping that data locked away forever.
Encrypt your data
You don't need fancy software to securely wipe your phone and make it ready to sell or donate, you just need to encrypt it first. This is the one and only step, and while it is a bit more time consuming than simply resetting your phone, it ensures that someone with the skills to get to the data you left behind will have to tear down one heck of a wall to do it. Bear in mind that the process can’t be reversed.
Head to the Settings app, and under Security, you’ll see a few settings for device encryption. If you’ve got an expansion slot, your device might also offer the option for you to encrypt the SD card located inside; but you don’t need to worry about that if you pop it out and keep it for yourself.
The device will take a while to encrypt depending on how much data you have, often up to an hour. But when you’re all done, you can perform that factory reset knowing that, while your data is technically still there in all the "blank" areas of your phone's storage, it's encrypted and can't be easily read.