Please Try again!
How Do I Securely Erase My Phone Before I Sell It?

How Do I Securely Erase My Phone Before I Sell It?

Eric Ravenscraft, Gawker Media

How Do I Securely Erase My Phone Before I Sell It?

Dear Lifehacker,
I'm about to sell my phone, and I want to erase my data. Are the built-in methods secure? Could someone with data recovery software still uncover my private information?

Total Wipe of the Phone

Dear Vague Bonnie Tyler Reference,
good news is that, in general, most phones are pretty good at securely
removing your data when you're done with the device. There are still
some measures you need to take to protect yourself before you pass the
handset off, though.

What Everyone Should Do

How Do I Securely Erase My Phone Before I Sell It?

No matter what type of smartphone you use, there are a few basic things you should check outside of wiping your phone:

    • Remove your SIM card: While most of the data that you store is kept
      on your internal storage or micro SD card, it's still possible for
      contacts or call logs to be kept on your SIM card. The person you're
      selling it to has no need for this, so always be sure to remove it.
    • Remove
      your micro SD card: Similarly, if your phone has a micro SD card,
      chances are you don't really want or need to give it away. To truly
      ensure that the data on your micro SD card is secure, keep it to
    • Erase and format your SD card: If you absolutely have
      to include your micro SD card with your phone, then you'll at least want
      to erase and format it. You can usually do this via the Settings app.
      You can also do it by connecting it to a PC, but if you format it with
      the wrong file system for your phone, it might not recognize the card.
      Again, though, the best way to secure your data is to keep your card.

    you've taken care of all this, the only thing that's left should be
    your device's internal storage. iOS and Android have slightly different
    ways of handling this, but both are mostly straightforward.

    How to Securely Wipe Your Phone

    How Do I Securely Erase My Phone Before I Sell It?

    the rest of this, we're going to talk about how to secure your internal
    storage, but first it's worth explaining a bit about how flash memory
    works. As you're probably aware with normal platter hard drives, data
    isn't really erased when you delete something. The internal flash memory
    in your smartphone isn't quite the same. Because it's not a magnetic
    storage medium, the methods used to recover data on an old hard drive
    won't be the same as tools to pull from your phone. Among other things,
    this means that while rewriting data seven times is a standard method
    for erasing magnetic media, it won't do much to make your data more

    That being said, for most of the average user's needs,
    your phone already has the tools built in to securely erase your phone's
    data. If you carry military secrets around on your unprotected Galaxy
    S4, well...for starters, you probably shouldn't. But if you do, you
    should probably consult someone with a PhD in something before you lose
    your phone in a bar. Everyone else may continue.

    iOS: Use the Default Erase Setting

    How Do I Securely Erase My Phone Before I Sell It?

    iOS users, your job is pretty simple. The iPhone has built-in options
    that securely erase your phone. On old phones, it goes through a long
    secure erase process, but on the iPhone 3GS and iOS 3.0, Apple moved to
    hardware encryption on its phones. From that point on, all data you
    store on the internal storage (which, aside from anything on the SIM
    card, is everything) is automatically encrypted. Your phone uses a
    device-specific key that's never stored anywhere but your handset.

    supported iOS devices wipe your phone, what's really happening is that
    the hardware-specific encryption key is securely wiped. Everything else
    on your phone is left an unintelligible mess ,
    even if someone were to use a fancy forensics lab to physically examine
    the memory chips which 99% of you will probably never have to deal

    So what do you need to do to securely erase your phone? Just head t

    Settings > General > Reset > Erase all Content and Settings.

    it. On any iPhone including or following the iPhone 3GS (as well as all
    iPads and any iPod Touch 3rd Generation and later), this will use the
    hardware encryption method described above. It will be very fast, yet
    still leave your data secure. For any older devices, the process will
    actually take a lot longer, as iOS will overwrite all of your data with
    random information to prevent it from being read later. Either way,
    though, this should be as secure of a wipe as you can get.

    Android: Encrypt Your Phone, Then Erase

    How Do I Securely Erase My Phone Before I Sell It?

    phones are set up a little differently from iPhones (shocker, I know),
    and they vary somewhat from manufacturer to manufacturer. However, in
    general the default options are mostly secure. We talked with Android
    security researcher and Elite Recognized Developer on XDA jcase and he gave us a few pointers in the right direction.

    Unlike the iPhone, Android encryption
    is not done on a hardware level. For starters, this means if you want
    to have your phone encrypted, you'll need to enable it manually in
    Settings. This process will take a while and, from then on, you'll need
    to enter a PIN when you first boot your phone (not to be confused with
    your lock screen PIN). It can also cause some slight performance
    decreases, so keep that in mind. This process also can't be reversed
    without wiping your phone, so consider carefully before you commit.

    on Android, you have two options for wiping your phone: you can either
    do a factory reset (located in different places depending on your phone,
    but should be under something like "Backup & reset") which will
    wipe everything you've ever stored in any user-accessible area of storage . For most people, this will be enough to ensure that no one will be able to access data you've ever stored.

    effective a basic wipe is can depend on how well the manufacturer
    implemented its factory wipe. When we spoke to jcase, he said that some
    manufacturers' methods can still leave behind recoverable data.
    Additionally, if you root your phone and use a custom recovery, wiping
    via the recovery might not do everything properly.

    While, ideally,
    you shouldn't have to overwrite your phone to erase data using a
    factory reset, if you're unsure or want to be extra safe, encrypting
    your phone (usually found in Settings under "Security") before wiping it
    can provide some reassurance. Just be aware that it may be redundant on
    certain phones. Still, better safe than sorry.

    Of course, the last line of defense before you sell your phone is to vet your buyer .
    If you're using a CDMA device, be sure to deactivate your phone with
    your carrier before handing it off. And while you're at it, make sure
    you've taken care of your phone and are selling it for as much as possible . Alternatively, there's the ultimate security tool if you're worried about someone pulling data from your phone: don't sell it.


    Photos by Jack Spades , and warrenski .

    Contribute to LifeHacker

    Write for Us

    Subscribe for latest stories