How to make a Deleted File Unrecoverable

What happens when we delete files from our computer using the Shift+Delete command ?? Well most of us think that the file is completely removed. But in actual case it is not.  So what happens then ?? The files are allocated a space of memory in the physical hard drive every time we move it there.

And when we perform the most common permanent deletion that very allocated space is freed & gets ready for saving another file there. The deleted file remains recoverable until something else i.e. a new file replaces it. So how to permanently delete a file which makes it un-recoverable. In this post we will see to it.

There are basically two ways that completely wipes out all the data in our hard drive making the older data un-recoverable.

1. Formatting the drive. Which is obviously the first & best choice.
2. Or as we have already figured out in our intro, replacing the old files with random data which can be achieved by using certain(or most) data wiping softwares.

Two main methods of overwriting data :

  • The Guttman Method : This theory is based upon Peter Guttman theory “Secure Deletion of Data from Magnetic and Solid-State Memory“. This is the most secured file deletion process. The data deleted using this concept is overwritten 35 times using carefully selected patterns. But like all other most effective ways, this is also very time-consuming.
  • US DoD 5220-22.M : This concept is based on the United States Department of Defense recommendation 5220-22.M. Like the Guttman concept it also overwrites the data but in this case the data is overwritten 7 times only. Well this is secured but not as much as the earlier one. But this is time saving other hand.

For MAC users :

All the Mac users have a built-in data wiping utility. To perform this follow the instructions below :

  1. Move the file/folder(that you want to be deleted permanently from your system) to the Trash Can.
  2. Now from the Finder menu select Secure Empty Trash.

mac-finder

Other than these you can also use the Disk Utility program Erase Free Space. It scans your hard drive for unused space and & deletes them securely using either US DoD 5220-22.M or the Guttman concepts(mentioned earlier). It can found in the Utilities folder.

For Windows users :

Well windows has no such built-in utilities available. So we are going to do this using a dedicated software named Eraser to solve the purpose.

Eraser is a free & open source software that works with almost all Windows Operating Systems including DOS. You can delete a file or folder or simply a complete drive using this software. Lets see how it is done.

  1. Download & install the software.
  2. Once installed you can use it to schedule an erase or do it right then.

erase-list

You can select files/folders to delete by

  1. Dragging-n-dropping selected files and folders from Explorer to the list.
  2. Copying selected files and folders to the clipboard and pasting them to the list.
  3. Or simply using the New Task command in the File menu.

NB : Using the New Task command, a window will open letting you select unused space on a drive, a folder or a file that you want to delete.

After the selection of the Files you need to select the way of removing them

  1. The Gutmann Method (Default).
  2. The US DoD 5220-22.M Method.
  3. The Pseudorandom Data Method. In the pseudorandom data method, all passes will be randomly generated data, which are highly incompressible. This method should be used when erasing unused space or data on a compressed drive. The number of passes varies from one to 65535.

After all this, you have to finally confirm the deletion in the final step. This ensures that there is no accidental deletion of files.

The last & best way……

Well all the earlier works just fine, but if you are not sure of them then use the last & final way out

  1. Remove the Hard disk from your machine.
  2. Remove the disks from the casing.
  3. SMASH it on the floor, & its done. Now all your data is securely deleted. :)

Jokes apart I must remind you one last thing.

About formatting…..

Just like overwriting any data works only formatting won’t delete your files securely. Overwriting them is also necessary. And when I’m saying “format” it strictly means full-format & not quick-format.

Well on a signing note I must accept that there are zillions of softwares that does the same job for yet many operating systems. So if you know any such then please share your experiences good or bad in the comments. Thanks in advance for that.

- the founding editor of Ampercent. Connect with him on Twitter or be his friend on Facebook.