When you delete a file in MS Windows (also true to almost all the other operating systems) it just ‘lazily’ removes the file only from its index, rather than individually cleaning up (deleting) each ‘sector’ that constitutes the file. This is also the reason why anyone can attempt a recovery of deleted files later (might not always work though).
An operating system does not try to ‘securely delete’ a file simply because it can take a considerable amount of time (depending on the file’s size and many other factors, such as due to limitations of the file system for instance) and for most people, under most circumstances, securely deleting files might not be necessary at all.
But, let’s say that you’re giving away your PC or HDD for example and got worried that even after removing all the partitions and reformatting the disks etc, someone might still be able to recover your data (highly possible!), then you should use some sort of a secure file deleting utility.
If you’re looking for a extremely small (about 36 Kilobytes!) and a portable tool, then try ‘Blank And Secure’.
What it does is simple, just like any other application, it first scans the file and finds the sectors that hold the file’s data and then simply overwrites all those sectors with ‘NULL data’ (‘zero byte’ files, garbage content in other words :D).
Main features …
*. No installation is required, just extract the ‘executable’ inside the compressed archive, save it to somewhere (say on an USB drive) and then simply double click on it to run.
*. Pretty easy to use as you can just drag and drop files or folders for deleting.
*. Overwrite the file from ’1′ to ’32′ times.
*. Has an option to delete the ‘free space’ of your storage device.
This is another important factor when it comes to this, because, even if you securely deletes a file, a copy of it might be available in the ‘free space’ in that drive, but how?,
Well, there can be multiple scenarios, but one way that could happen is that; let’s say that you copied a file to a new location (in the same HDD) and then deleted the original file later. Now those sectors will be marked (added) as ‘free space’ (meaning that all the data is still there in those individual sectors, unless it’s over written by the data of an another file) by the operating system.
But still, because deleting that previous copy of it doesn’t securely remove it, and unless it’s overwritten by another file (say that you copied another file to the ‘free space’ of that location, actually even that won’t do it sometimes but I won’t go into all the details as the article could more boring that it is already :D), one would still be able to recover it by scanning the ‘free space’ of that storage location.
So, if you’re quite paranoid about the safety of your privacy ;-), then having the ability to wipe out the ‘free space’ too should be a necessity.
*. Change the ‘delete delay’ (by default, when you press the ‘delete’ button, it gives you ’5′ seconds before starting the process).
*. You can cancel the process anytime by pressing the ‘Esc’ key on your keyboard.
That’s pretty much it.
Does it really work?
Well, in theory, a secure file deleting tool should be able to wipe out data without the possibility of recovery. However, due to various reasons (as said early, due to file system’s limitations for example) all the data might not be securely removed.
Now I didn’t test it with like millions of recovery tools ;-), but after deleting a file (‘iTunes’ setup, 73.2 MB) I did try to recover it using a popular tool called ‘Recuva’ and another one called ‘Freerecover’. At the end, they both failed.
‘Recuva’ however, after about 40 minutes of scanning in its ‘deep scan mode’ (its best ‘mode’) found a file about the same size (but with a fake name) that had been deleted, and gave me the below ‘comment’ in its ‘Info’ window …
This file is overwritten with “D:\?\DEL_0WVC4_R301516_XRXXX03.cap”
Now I assume that the ‘DEL_0WVC4_R301516 …’ file is the ‘NULL’ data that ‘Blank And Secure’ used and again, they both were unable to recover the deleted file nonetheless. So yes, ‘Blank and Secure’ works really well it seems.
If interested, you can get it from this ‘Blank And Secure’ home page.
Please use it at your own risk though (just in case! ;-)) and also remember that, after deleting a file using such tools, recovery will become an impossible task (most of the time). So be careful.