Clear data before giving away or selling your devices


Virtually every ‘smart’ device and of course computers, smartphones and tablets have local storage. Often in the form of a flash memory or SSD, or even as a hard disk if necessary. Just quickly formatting that storage is often not enough to ensure that others can no longer access your data after selling or giving it away! This way you can erase all data from your devices.

Few Windows users use full disk encryption via Bitlocker. For Apple users, that looks a lot more favorable. More recent iMacs and MacBooks have built-in hardware to enable encryption in real time and on the fly. But it is precisely the older Macs that do not have that trick on board. You can enable full encryption (just like with the new Macs via File Vault), but many people don’t because it takes time to realize it. Now that encryption has another advantage, in addition to the fact that if your computer is stolen, no one can access your data without a password, fingerprint, PIN or whatever. We’ll be right back!

Wipe

In short: many systems will contain unencrypted data. Are you still under the illusion that by simply formatting the hard drive in your PC or notebook you have destroyed everything that was ever stored on your system? Then the harsh reality is different. Via a simple free tool like Recuva any malicious brute can retrieve the vast majority of your ‘erased’ data in an instant. That this is possible is a godsend if you accidentally delete files. But it is a curse when selling or giving away your computer. To prevent your data from being recoverable, it is necessary that your storage medium is thoroughly erased. This is also called wiping and in short it means that your storage is filled with – preferably random – numbers. And preferably a few times in a row. This ensures that even with advanced equipment it becomes almost impossible to recover anything useful from such a wiped medium.

Built into Windows 10 (and 8)

You guessed it: that is a rather time-consuming job, especially with large traditional hard drives. Moreover, hours of sequential writes to a modern storage medium such as an SSD are very unhealthy for that. SSDs therefore often have an option built into the controller to safely wipe that thing, without excessive wear and tear. You can usually find that option in the tool that comes with the SSD (or downloadable). Make use of that and then ignore third-party software. Furthermore, Windows 10 – finally – has a built-in disk wipe tool. You reach it by clicking Settings clicking the Start menu. Then click Update and Security, followed by a click on System recovery. Then, under the Reset this PC heading, click the To work. In the window that opens, click Delete All. In the Additional settings step, click on the link Change settings.

Click here on Change settings.

Beware of SSD

Turn on the switch under Delete data and click Confirm (see image at the top of this article) to go through the rest of the wizard. As you can read in the ‘footnote’ to this option, this process will take a few (to many…) hours. That’s right: your disk is overwritten several times with random or non-random numbers. External software is therefore no longer necessary. It still exists, by the way, for enthusiasts who want to have more control over the entire process. You can read how to proceed in this article. And – again – to protect your SSD from overheating and (or) too many write cycles, use the wipe tool provided with your SSD!

mac

Macs also have a built-in tool for securely and thoroughly erasing storage media in them. on this page Apple itself explains in great detail how to do that, so it makes little sense to type it again here. Be especially alert at step 8: (Optional) Click on ‘Security options‘ if this button is available. Then use the slider to specify how often the erased data should be overwritten and click ‘OK’. It is here that you specify how securely your drive is erased; the more often overwrite, the safer. Once or seven times is very sufficient, once or three times is sufficient if you are in a hurry.

iPhone & co

Mobile devices usually also have an erase function. On the iPhone and iPad, for example, you can find it in the Settings app. Click on it General and then Reset. Then click on the link Clear all content and settings and follow the further instructions. Because the storage of these devices is completely encrypted, you will see that the ‘wiping’ is quite fast. If the key that gives access to your system is deleted from the security chip (core), the data on your storage will only be a mush of random numbers. Exactly what we want. The encryption in these systems is so strong that you cannot break through it with even the most advanced equipment. That same full disk encryption also makes Macs extremely secure, provided you had that option turned on. Combine it with overwriting your storage a few times and you can be 100% sure that no one will ever get any meaningful information from your system again.

Safely wiping an Apple mobile device is a breeze.

android

Android devices can also be ‘wiped’ via the settings and advanced options (see, for example, this article. But there is a catch: it turns out that certain data can still be retrieved if your phone was not fully encrypted before the ‘factory reset’ aka You can read how to enable encryption – in addition to various other security tips for Android – in this article. Keep in mind that if your Android phone or tablet is not yet encrypted and there is a lot of data get up, this process can take several hours, so leave the device on the charger, a great job for nighttime hours.

Router, smart TV, streamer…

Think carefully before you give away another smart device. Your router contains all kinds of privacy-sensitive information. Including at least login details for your provider. And with advanced types, there may be a range of other things like VPN credentials, files stored on internal storage, Wi-Fi data and so on. A factory reset prevents potential woes. The fact that you wipe a NAS before giving it away goes without saying, but something as banal as a smart speaker already contains a lot of information about you. Including at least the account details of, for example, Google, Amazon or Apple. If you leave it behind when giving away or selling, everyone can find out your entire usage history via your account. We don’t think it’s a pleasant thought. Every smart device (just to name a few examples: smart TV, set-top box, media player, etc.) you really need to clean before it leaves your house. If that is not possible for whatever reason, then it is better to just put the thing in the attic or come up with another application for it.

Car

Last but not least is your car. Many modern cars have an on-board computer and built-in navigation. This way, a buyer of your car can easily find out your address, even if that car is sold through an intermediary or dealer (although you can hope that the latter thoroughly deletes all usage data before selling). Also keep in mind that many cars offer the possibility to perform actions such as hands-free calling via speech recognition. Phone numbers from your mobile can often be transferred to the on-board computer. Handy, because you can call your contacts from any phone. Only: those contacts remain present when your car is sold. Read the instructions on how to delete that data.

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