How To Securely Delete Data On Your Computer

I promise that after reading this post, you will be able to securely delete any digital data you have on your computer to the point where recovering it will be extremely difficult next to impossible. Pretty much just like what a paper shredder will do for your documents. Except that this time around, we are substituting actual paper with your digital data which could consist of anything including but not limited to your word document files, photos, classified PDF documents, music files, video files etc.

When we talk about data that is on your computer, there is always the chance that you have some type of important document that you never want a stranger to see. Now you’re probably scratching your head wondering isn’t that the job for the recycle bin? To delete my data? Technically speaking, yes, the recycle bin is there to help you delete your data but to be more precise and detail, it doesn’t actually help you ‘securely’ wipe out the data. What I mean is that by using some type of file recovery software ranging from various freebies you can download to the very expensive programs that professionals use, they are able to scan your hard drive and reconstruct what you thought you have deleted by emptying your recycle bin!

To better understand this, there is an excellent analogy that I use every time that will put everything into perspective about how a hard drive stores and deletes data. First, imagine that the data you have on your hard drive as books and that your hard drive is actually a library. A library has tons of books and your hard drive have a ton of files. Now picture yourself entering this humongous library trying to find a book. It would be very unproductive if you were to just blindly stumble in any direction without knowing exactly where the book is located. Instead, you would most likely consult with a catalog or some sort of index the library has maintained detailing where each book is stored and under which category. Armed with this information, it is now much more easier to locate the book you are looking for. The same scenario is true when we are talking about how a computer locates files that you want to access. There is a catalog that it consults (NTFS, FAT32 etc) to find out where the files are. Now can you guess what happens when you ‘delete’ a file from the recycle bin?

That’s correct, the file themselves do not actually get deleted! Instead, what happens is that the file’s entry in the ‘catalog’ gets erased and the hard drive location space which the unwanted files have occupied will now be marked as empty. Therefore, the next time you save a new file to your computer, it will now know that it can write the new files that you want to save in the location of the previous occupied files. It will then overwrite that hard drive location with the new data and then will your previous files get overwritten and usually deleted. This also serves as another reminder. If you accidentally deleted an important file that you need to recover and have no backup of it (shame on you!), then what you need to do is immediately stop using the computer as much as possible. Why? Well, the more you use the computer, the more files will get written on the hard drive and with more files being written, the more chances of those files overwriting your previous files which you need to recover.

So now that you have a general knowledge of how data is stored, it will be easier to understand how secure file deletion applications work. Just like how overwriting your previous file locations will get rid of the unwanted files themselves, secure deleting applications work almost the same way. They ‘securely’ delete your important files by ‘overwriting’ them with random gibberish. That way, recovering them will be pretty difficult if at all possible. That is why you must be absolutely sure that you want to securely delete a file/hard drive before doing so because there is usually no going back. With that understood, I will now show you two awesome methods of securely wiping data on your hard drive.

The first is a awesome freeware tool called DeleteOnClick which is developed by a company called 2BrightSparks. This tool will integrate with your Windows right click menu so using it is extremely easy. Whenever you want to securely delete a file, all you need to do is to right click on that file and from the menu choose the option of ‘Securely Delete’. Of course, it will ask for a confirmation so if you selected it by accident, you can simply cancel the operation. If you do want to proceed, then simply hit the ‘Yes’ button. In the background, it’s overwriting that file location numerous times with random data so that it will not be recoverable anymore. One thing to remember is that because it needs to overwrite that file location numerous times with random data, the larger the file you want to securely delete, the longer the process will take.

DeleteOnClick By 2BrightSparks

The DeleteOnClick method works well for individual files but what if you want to securely erase all the remaining space on your hard drive? For that I will show you a secret method of erasing your hard drive that even some professional computer gurus do not know about! There is no install necessary. Why?! Are you ready for this? The tool is built directly inside Windows! So why haven’t you heard of this feature before? Simple. It’s command line based. That’s right. No pretty pictures for you to look at and certainly no icons to double click on to start the process. The Cipher command is used in the command line environment for encryption tasks like encrypting and decrypting a file/folder on your hard drive. The secret is when using this command with the /W switch. Using this will tell it to securely erase all of your remaining hard drive space three times over. First it will write all zeroes. The second pass will write the number 1. Then the third and final pass will overwrite the space with random numbers making this method really secure. I will now show you how to use this awesome feature.

#1 Open a command prompt
For XP users, hit the Start Menu, click on the run box and type in cmd, then press OK. For Vista, type in the word cmd in the search box and then right click on the command prompt application and run it with Administrator rights.

#2 Starting the deletion process
Once inside the command prompt, type in cipher /w:C: You can substitute the letter C: for whatever drive letter you want to erase data on.

#3 Wait…Wait…..and….Wait some more
Now you simply sit back, relax and let the process take place. The more empty space you have on your hard drive, the longer the process will take. If you have several hundreds of empty gigabyte space, then it’s best to run this process before you hit the bed to let it run overnight. Once the process finishes, your hard drive should now be securely wiped out and it will now be really difficult to recover any meaningful data.

Securely wiping out your data definitely has its advantages. For one, if you travel a lot with your laptop, then it is even more important that you securely delete your important data. If you lose your laptop, the attacker can simply use file recovery tools to check out what you have deleted and see if they can use any of that information. Also if you are planning on selling your hard drive, you best believe that a simple reformat of the hard drive is not enough. I have heard horror stories of researchers buying used hard drives on Ebay, running recovery tools on those hard drives and finding tons of secret information that should have been securely deleted. There was even a time when some person found that a used hard drive he bought from Ebay contained top secret, confidential military secrets! Luckily, he turned the drive over to FBI. However, others might not be so lucky.