Delete Doesn’t Mean It’s Gone Part 2

Secure deletion of single files

Deleting single files in a secure and final manner is not as easy as it sounds. In most current operating systems, deleting files only means that they are moved to the recycle bin from where they can easily be restored. Even if the bin is emptied afterwards the data may still be recoverable. Therefore, we are going to detail the various options you have to delete data in Windows on HDD and SSD drives .

Side note: Mac OS X allows to choose ‘secure empty trash’ when emptying the recycle bin to safely get rid of data. This option, however, was removed with the introduction of Mac OS 10.10 Yosemite and only works on regular hard drives.

Deleting data on HDD

There are several different applications that can delete single files on HDD drives on Windows.
Eraser is an open source tool that allows for intentionally delayed deletion of files. It features a well-structured user interface and reliably deletes files. The user can choose between 13 different deletion methods. The option ‘Only first and last 16kb’ should not be selected as files are not completely overwritten. The ‘Gutmann-method’, on the other hand, goes far over what can be considered reasonable. With modern hard disks overwriting files once is generally enough, since afterwards recovery of files is almost impossible.
Eraser can also overwrite the space marked as empty on hard disks to make sure that any possible remnants of deleted files are gone as well.

BleachBit is a system cleanup tool that is able to delete temporary data created by other applications. The program is contextually aware of which temporary data is still in use and what files can safely be deleted without impacting the operation of other software or the operating system. BleachBit can not only delete cache data, but also error reports created by Windows and similar remnants. Additionally, it can overwrite free space on the hard disk and delete clipboards. BleachBit is very easy to use and a manual can be found here.

If files cannot be deleted because they are still in use by other applications, LockHunter and Unlocker may be of help. LockHunter enables the user to delete files in Windows even if they are locked by one or more processes. It shows which processes are holding on to a file and enables a circumvention of the lock they create. LockHunter can also stop processes or delete them entirely. The app integrates with the context menu and can be used from anywhere in the system with a simple right-click. Caution: The files that are deleted with LockHunter are not completely erased, but are moved to the recycle bin to allow for easy recovery.
Unlocker can also be used in case some application is blocking access to a file so it can still be deleted or moved. Similar to LockHunter, it integrates with the context menu and can be started with a right-click. This allows the user to delete a folder or a single file without having to end other processes. This free tool even deletes files that are locked by Windows because they are in use or because they need different user privileges (be careful with system data). You can find more information on the differences between Unlocker and LockHunter in this article. Using Unlocker is easy: Simply right-click a file or folder and select ‘Unlock All’.

Deleting data on SDD

Single files cannot be deleted securely on SDDs. Some drive manufacturers provide specific instructions or even a program but not all of them erase their data reliably.
Rather than using secure wiping tools, you should just enable file-drive encryption. Windows 10 has Device Encryption enabled on many new PCs, and Professional versions of Windows also offer BitLocker. Mac OS X offers FileVault encryption, Linux offers similar encryption tools, and Chrome OS is encrypted by default.

When you use full-drive encryption, you do not have to worry about someone getting access to your drive and scanning it for deleted files.
Encryption will be the main subject of our next blog post where we will explain the most important aspects of it.

Conclusion

The importance of privacy in the digital realm has only increased with the new possibilities of collecting and disseminating data, not only for companies, but also for individuals. The methods detailed in this and the previous blog post of deleting single files and entire hard drives are intended to enable users to prevent misuse of their private data. Naturally, responsible handling of information guards against unintended circulation of data and shields against prying eyes in private areas. Depending on the storage medium, however, there are certain limits to the secure deletion of data. If you are considering to completely get rid of certain data, you can always find help with the Neptun Help Points in Zurich, Basel, and Lucerne. Still, reliable backups are a key part of safe data management. You can find more information on this topic in our post ‘Backup – a basic necessity’.