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Selling your phone or tablet? Here’s how to ‘completely wipe’ your Android device

Our smartphones are privy to some of our most important secrets. Sensitive business emails, financial details, contact information, and even the odd risqué photo are not things you want falling into the wrong hands.

Performing a factory reset is always a good idea, but it might not be enough. For example, the security firm Avast bought 20 Android smartphones from eBay recently and was able to recover photos, Google searches, emails, text messages, and contact details.

We’re going to show you how to make sure that can’t happen to you.

How does a factory reset it work?

When you do a factory reset on your Android smartphone it’s supposed to wipe it clean, but it doesn’t. It deletes the addresses of all of your data, so it no longer knows where it is stored, but it doesn’t actually overwrite the data. It’s possible for someone to employ off-the-shelf recovery software and get some of that data back. Let’s look at how to wipe your Android smartphone properly.

Encrypt your dataScreenshot_2014-07-24-10-38-50

The first step is to encrypt your data. This option is built in to Android and it requires you to put a PIN or password in every time you turn the phone on. It means that anyone attempting to recover data from your phone after you will need a special key to decrypt it, and they won’t have the key.

  1. Charge your phone fully or keep it plugged in to the charger while this process is running because it can take hours depending on how much data you have.
  2. Go to Settings > Security > Encrypt phone. You have the option to encrypt the SD card, but if you’re passing the phone on we would recommend removing it instead.

Factory reset the phoneScreenshot_2014-07-24-10-39-20

Make sure that you have anything you want to keep backed up before you do this because it will wipe everything.

  • Go to Settings > Backup & reset > Factory data reset and then tap Reset phone.

When it’s done your phone will be wiped and any data that could be recovered will be encrypted and should be impossible to decrypt. It’s now safe to sell your Android smartphone or pass it along to someone else.

Overwriting with junk dataiShredder

If you want to be absolutely certain you can overwrite the encrypted data with junk data and then perform another factory reset and it would be genuinely impossible to recover any of your old data. This is probably overkill. If you want to do it, then simply load a bunch of dummy data onto the phone until the storage is full (a few large video files should do the trick) and then perform another factory reset.

You can get an app to do it for you. There are a few options in the Play Store, like Secure Erase with iShredder 3.

There you have it. That’s how you completely wipe your Android phone. Let us know if you have a better technique.