Required before smartphone disposal!How to erase the data without completely

When dispatching or selling smartphones that are no longer needed due to model changes, security is security.If you inadvertently, there is a risk that your personal information will reach the hands of a third party as it is, so delete the data firmly.

■ Whatever the OS is, the first thing to do

No matter what smartphone you use, you need to check some basics before the data is erased.

If you check all of the above, only the internal storage device of the mobile device remains.The iOS and Android have slightly different ways to erase the data in the internal storage device, but both are almost easy.

■ How to safely erase smartphone data

From now on, I will introduce how to erase the data of the internal storage device safely, but before that, it is better to explain a little about the flash memory mechanism.

As you know, with regular hard disks, the data is deleted does not mean that the data is actually erased from the magnetic storage medium (platter).The flash memory inside the smartphone is slightly different.The smartphone storage device is not a magnetic storage medium, so you can't restore smartphone data by restoring old hard disk data.Conversely, the standard way to erase the magnetic storage medium was to write the data seven times, but this method is not very useful for completely erasing smartphone data.

Nevertheless, most smartphones have a built -in functions to save data safely.Average users should be able to fulfill their needs.If you are saving military secrets in Galaxy S4, which is insufficient security (although it is wrong to do that in the first place), in that case, before you lose your mobile phone at the bar,It's better to consult a great person or something.If the average is not, please read more.

■ iOS: Use the default erasure settings

iOSのユーザーなら、データの消去はとても簡単です。iPhoneには、スマートフォンのデータを安全に消去するオプションが内蔵されています。古いモデルの場合、安全に消去するためには長い手順を踏む必要があるのですが、iPhone 3GSとiOS 3.0からは、ハードウェアベースの暗号化が導入されました。それ以降のモデルでは、内部記憶装置に保存されるすべてのデータ（SIMカードのデータを除くすべてのデータ）が自動的に暗号化されます。各スマートフォンで端末固有のキーが使われ、このキーが端末の外に保存されることは、絶対にありません。

Erasing the data using this function of the iOS device will completely delete this hardware -specific encryption key.Then, all data stored on the smartphone will be messed up and cannot be deciphered.Even if someone asks a scientific investigation team that appears in the drama and physically verifies the memory chip, it is impossible to decod.However, 99 % of you will not have to worry about such a situation.

So how do you specifically to erase iOS devices such as iPhone / iPod safely?Please operate as follows.

「設定」＞「一般」＞「リセット」＞「すべてのコンテンツと設定を消去」Appleサポートより

Only this.In the iPhone 3GS or later iPhone (and all iPads and the 3rd generation iPod touch), the data is erased using the hardware encryption method described above.It ends in no time, but the data will definitely be erased.In the case of an earlier terminal, it takes more time to erase it.In this case, there is a method in which iOS overwrites all data with random information and cannot be read.Either way, the data will definitely be erased.

■ Android: Encrypt your smartphone and then erase it

The setting of the Android device is slightly different from the iPhone.The settings vary slightly depending on the manufacturer.But the most secure is the default option.JCASE, who is studying Android security and has been recognized as a "developer with excellent knowledge and proven track record" in the XDA developer forum, taught some guidelines.

Unlike the iPhone, Android encryption is not performed at the hardware level.In other words, if you want to encrypt your smartphone, you need to manually enable encryption from the setting menu.This process takes a little time.

After encryption, you need to enter the PIN code every time you turn on the smartphone (it is different from the PIN code to be entered when unlocking the screen).Also be prepared for the case where the performance is slightly reduced.Once you encrypt it, you will not be able to restore it unless the data is initialized, so please think carefully before execution (reference).

Android has two options for erasing data.One of them is to reset it to the state of the factory.The operation method varies depending on the terminal, but it should be found in a menu such as "backup and reset".

In this method, all data stored in the storage area that the user accesses is deleted.Most people can think that just performing this procedure will not access the data you saved.

How effective this basic erasing method depends on how much the manufacturer has reset.According to JCASE, some manufacturers may have restorable data.Also, if you have rooted and introduced custom recovery, you may not be able to completely delete it with recovery data.

If you reset to the state at the time of the factory and delete the data, you do not need to overwrite the data theoretically.However, if you are uneasy or if you want to be careful, if you encrypt your smartphone and then execute it from the "security" "settings), you can get a sense of security.It is.Some smartphones have a setting that doesn't have to be done manually, but you won't be careful.

Of course, the last fort for selling smartphones safely is to strictly examine the buyer.If you are using a CDMA mobile phone, be sure to cancel your contract with a telecommunications carrier before letting go.And if you sell it anyway, do it properly and sell it at a high price as much as possible.

If you are worried that data will be stolen, let's teach the ultimate security measures -not selling smartphones in the first place.

Eric RavenScraft (Original / Translation: Tomoyo Umeda / Galileo)

Photos by Jack Spades, and Warrenski.