How to properly clear data

If you want to sell or dispose of PCs, computers or hard drives, you need to be careful. Because if you don’t know what you are doing, you are putting your personal data in the wrong hands.

If the computer is to be sold or disposed of, one thing is important: make sure there is no longer any personal data dormant deep inside the system, especially if it includes data from third parties, such as relatives, acquaintances or business partners.

Data on the computer that is deleted via the recycle bin generally only superficially disappears from the scene. But they are still present on the hard drive. Because when the recycle bin is emptied, only the references to the data in the hard drive summary are deleted, warns the German Federal Office for Information Security (BSI). The data would be released for overwriting, but this may never happen.

Hammer for maximum effectiveness

If you still want to take your old hard drives or computers to the recycling yard, you can also use physical methods to delete the data. These are brutal, but at the same time more effective, says Patrick Bellmer from the specialist portal “Heise Online”. Specifically: hit it with a hammer or hit a nail in the hard drive. After that, with the best will in the world, no more data can be found. Most notebooks could easily be unscrewed to reveal the hard drive, however desktop PCs.

Picture: Jens Kalaene / dpa-Zentralbild / dpa-tmn

The first thing to check is whether the hard drive of the computer is encrypted or not, advises Patrick Bellmer from the specialized portal “Heise Online”. If this is the case, as is the case with modern Apple Macs, all that needs to be done is to remove the user account. This is done the same as when resetting the smartphone. The personal data is still there, “but encrypted so that no one can access it”.

The chips offer safety and convenience

With Apple products, encryption is performed by the T2 security chip and is usually built into all newer models. The user can also block the boot process, for example in case of theft.

Additionally, there are also free tools that overwrite the drive with “meaningless data,” Bellmer explains. These are tools like “Disk Wipe”, “HD Shredder” or “DiskPart” built into Windows computers, a command line program for partitioning the hard disk.

“Disk Wipe” does what its name promises: it completely removes data from your hard drive, so even professionals can’t restore it. The tool can also be used to clean USB sticks or SD memory cards and other mobile devices, reports «Heise Online».

I ran a system partition nut

However, the tools described cannot delete the system partitions on which the operating system is located. If your computer is to be sold or disposed of, it might be a good idea to dispose of these as well.

To do this, the computer must be started with a so-called live system or with a data shredder capable of booting the system itself. The operating system that the computer starts with is not on the hard drive, but on a USB stick or DVD. “Darik’s Boot and Nuke” (DBAN) is one such program.

While this process makes a classic hard drive with magnetic disks, the so-called hard drive (HDD), long-term “flat”, a different approach is required for modern hard drives (SSDs) that work with memory chips. Here, the Secure Erase command for secure erasing should be run through the SSD manufacturer’s SSD manager program. Alternatively, BSI recommends the “Parted Magic” program, which can also be used to restore data.

Smartphones are mostly encrypted

On the contrary, cleaning smartphones is particularly easy, says Patrick Bellmer. “The data is stored in encrypted form on all devices for the past four or five years. Without a user account, no one can access it. “This has been true at least since iPhone from iOS 8 and Google’s Android mobile operating system from version 6. Since Android 10, Google has also required manufacturers to actually enable the encryption option using factory settings.

Data overwrite tools are also available for smartphones. But resetting the device to factory settings is usually enough, says Bellmer. One thing should not be forgotten, however: it is essential to remove the SD card before sale or disposal, if available.

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