All personal data concerning you are stored on your computer and, more precisely, on the hard disk. If you plan to sell, reuse or give it away, it is essential to ensure that your storage media are correctly erased. Permanently erasing data is relatively easy on most hard drives to provide data protection and prevent it from being recovered by a malicious person. How this is done depends on the operating system used and the type of storage device with which the computer is equipped.
What is the permanent erasure of personal data from a disk?
Most users believe they can delete a file or folder by simply placing it in the operating system’s Trash and emptying it. This is not the case because if this method is used, the file remains on the hard drive. A lot of information is saved on the hard disk and referenced in a particular table the system accesses when it has to open the documents requested by the user.
When a file is deleted by emptying the Trash, the file system tells the operating system that the space used by the document is accessible. Still, the file remains there until another file overwrites the reserved area. Therefore, permanently deleting data stored on a contained hard drive means that information is written randomly and, if possible, repeatedly to the memory space where the data to be deleted is stored.
How to permanently delete data from a hard drive?
As we have already mentioned, the best way to permanently delete data from a storage medium is to write it back. Depending on the type of hard drive you have, there are specific erasure methods you can opt for, including reinstalling the operating system or using third-party data erasure software.
HDD Mechanical Hard Drive
The process of erasing a mechanical hard drive involves overwriting data. You can go through the option of resetting the PC and deleting data from the hard drive. If you want to recycle, donate, or sell your computer, the restore feature makes data recovery much more difficult, especially if it’s more encrypted. If you are on a Windows operating system and you want to erase your files:
Go to “Settings,” then “System” then “Update and Security” and finally, “Reset”.
Click “Reset” under “Reset this PC”
Select “Erase everything” (if you don’t want to erase your computer, you can use “Save my files” to deep clean your computer and improve its performance).
You also have the option of permanently deleting your data using deletion software. These erase utilities have in common that they all rewrite passes (binary ones and zeros) on the disk you want to clean up several times in a row. The purpose of this method is to make the data stored on the disk inaccessible. To use its data erasing utilities, you need to download them to a USB drive and run them from there.
Another method of erasing data from storage media is degaussing. Degaussing is erasing a hard drive from magnetic media, which is based on magnetic fields. During this process, a strong magnetic field (more than 10,000 gausses) is created, which neutralizes the information on the hard disk.
You probably have an SSD drive if you bought your computer in the last few years. These types of hard drives are faster than older mechanical hard drives and use flash memory instead of magnetic media. However, the disadvantage of this technology is that it is tough to delete files securely from an SSD drive. SSDs use a technique called “wear leveling” to extend their lifespan.
However, a side effect of this process is that confidential data may remain on the disk even after it has been erased.
So, instead of erasing the contents of SSDs with an erasing utility, it is better to encrypt them. It’s about manipulating data using a mathematical process and a key that only you know. Without this key, files on the disk appear as garbage. Even if someone manages to recover data after they are erased, they will not be able to restore them.
Can I recover lost confidential data deleted by mistake?
The different methods mentioned below can be used to erase data permanently. However, using any of these methods, lost data is accidentally deleted from the hard drive. Although these methods are based on overwriting the disk, recovering some of the deleted information is still possible.
Because even if you erase the hard drive and overwrite all the deleted files, there are traces of the original data left. Writing on magnetic media is more precise than one might think; when a file is overwritten, the new version does not completely overwrite the old one.
The remaining information can be read through specific data remanence techniques used by data recovery professionals. It is, therefore, possible to recover confidential data deleted by mistake.
However, it is good to know that malicious people can also use these recovery techniques to recover your personal information.
The only way to make data unrecoverable is to destroy the hard drive physically it is stored on. This way, you can rest assured that no software can be used to recover your sensitive data.