In a recent article I explained why it is impossible to recover data from a hard drive after overwriting it. In that post I mentioned that simply deleting files or formatting your hard drive typically does not remove or overwrite files at all, meaning they can still be recovered.
If this information made you a little nervous, let me connect the pieces for you and show you how you can terminally and permanently delete files, not only from your hard drive, but also from other re-writable storage devices.
Low Level Formatting
The kind of formatting most of us do is known as high level formatting, and whether you perform a quick format or not, your data won’t be deleted. What high level formatting does is set up the file system from scratch and in the process the information where files were stored is removed.
Low level formatting on the other hand re-initializes the disk and resets the values of each and every magnetic domain, which represents one bit, to zero. We have thoroughly covered formatting on MakeUseOf and if you would like to look into the details, I recommend the following articles:
- How To Format A New Internal Hard Drive
- The Difference Between Windows Full Format & Quick Format [Technology Explained]
- How To Completely & Securely Erase Your Hard Drive [Windows]
Low level formatting isn’t 100% efficient and may leave traces of data. If you wish to wipe an entire disk before you dispose of it, I recommend Darik’s Boot and Nuke, a boot disk that will automatically and completely delete data on any detected hard disk.
A walkthrough of Darik’s Boot and Nuke can be found in this article:
If you are already using CCleaner, you should know that it contains a Drive Wiper.
Open CCleaner and go to > Tools > Drive Wiper. You can wipe only free space or the entire drive, and you can choose up to 35 passes, meaning data will be overwritten with random strings of binary code 35 times. This very complex overwrite should make it impossible for anyone to restore the data originally saved in this space. When you’re happy with your settings click > Wipe and wait patiently.
Microsoft made it very easy to not delete files thoroughly. To make up for this potential security hole, they released a free command line utility called SDelete. This doesn’t make removing data any more convenient, but it can be considered a step in the right direction. Unfortunately it is a very small step, since Microsoft fails to provide instructions on how to properly open SDelete in the first place. Well, that’s what MakeUseOf is here for.
- the ZIP archive containing the tool and extract the folder.
- Click > [WINDOWS] + [R] to open the Run window.
- Type > cmd and click > OK to open the command prompt.
- Then move the > SDelete.exe file to the directory > C:\User\yourusername
- Now type a command in the command prompt, for example > sdelete -z to cleanse free space on your C: partition. A full list of commands is shown in the screenshot below.
Eraser is a freeware and open source security tool to completely remove data from your hard drive. It can overwrite data several times using randomized patterns of binary code. It essentially is a file shredder.
Eraser is more convenient than CCleaner’s Drive Wiper because it can delete and shred single files, rather than just wiping all free space on a drive, and it is integrated with Windows Explorer (right-click menu). Moreover, Eraser provides you with a host of advanced settings, for example different file and space erasure methods, the option to replace erased files with other files to allow plausible ‘deniability’, and schedule erasure of files, folders, recycle bin, or unused disk space.
The tool is also available as a portable app called EraserDrop Portable. It is part of the PortableApps suite.
We have covered Eraser in its (and MakeUseOf’s) very beginnings four years ago. Both have come a long way since. Feel free to check out the article here - How To securely Retrieve and Delete PC Files
There are several more file shredders that can securely delete files from your hard drive. Some of them were covered in the article 4 File Shredders to Make Deleted Data Unrecoverable. If you need to secure sensitive data without deleting it, you should seriously look into encryption and the article Encrypt Or Completely Wipe Files With the Axcrypt Encryption Utility [Windows] provides an excellent start.
Do you have nightmares of what someone might find on an old hard drive you discarded?
Image credits: R. MACKAY PHOTOGRAPHY, LLC