Delete and erase computer traces in Windows

This article was modified on 2012-06-05 16:02:39


If you`re here you already know that deleted data can be recovered from Windows. If what you want is to erase files permanently using a free software, my current recommendation is Eraser.

Short Eraser Review: The most important thing - this is a free, open-source security tool. It means that anyone can look at its source code. This is a great advantage when compared with similar shareware programs. What Eraser does is to allow you to select the data that you want to permanently remove and then it will overwrite the data several times with a pattern ( algorithm ) such as those designed by Peter Gutmann or Bruce Schneier.

Note: Technology evolved and as I am writing this, traditional hard drives ( the ones with platters that has magnetic disks ) are about to be replaced by solid state hard drives also known as flash-based solid state drives ( they use a flash chip ). They are already popular and the main reason is this: superior speed. According to a recent study conducted by several engineers at the University of California ( source here )  data recovery is possible on securely erased flash-based solid state drives ( SSDs ). If you will read the Secure Deletion of Data from Magnetic and Solid-State Memory ``Epilogue`` of Peter Gutmann computer scientist, I can`t only think at this phrase ``To erase SSDs...well, you`re on your own there.`` Based on this, I do have a recommendation: do not use Eraser or any other program to permanently delete data on SSD drives, unless you`ve found a tool that guarantees the deletion - which I doubt.

Quick Guide: You can download the latest version from Eraser homepage. The installation will look different on Windows XP and 7. If you don`t have the Microsoft Framework already installed in XP you will be required to download and install version 3.5. In Windows 7 you don`t need to - Microsoft framework 3.5 is already included. If you installed Eraser, locate the desktop icon:
Eraser Desktop ShortcutWhen you start Eraser for the first time - that`s how it looks like. At a first look it has only three main areas: ``Erase Schedule``, ``Settings`` and ``Help``.

Eraser interface

You might be tempted to go directly to first tab but before you do that, go to ``Settings`` section and choose your ``Default file erasure method`` ( my choice is Schneier 7 pass ) and ``Default unused space erasure method`` - I will choose the same method. Make sure that you also check ``Force locked files to be unlocked for erasure`` ( by default is selected ). Don`t forget to click on ``SAVE SETTINGS`` before you move on.

Note: There are several overwritting patterns or secure deletion methods. It is widely believe that more passes also means more secure. However, while this is true, keep in mind that it will also increase the time required to overwritte data. If the files that you want to delete are large it will also require even more time. My advice is to use Gutmann (35 passes) for secure deletion of extremely sensitive files in order to obtain maximum of security. If you don`t care that much and you just want to prevent recovery 1-2 steps should to the job. However, 7 passes seems to be the best compromise between paranoia and reality.

Eraser Settings

Let`s start to ``erase`` something so if you saved your preferences ( if you didn`t, go back ) return to first tab ``Erase Schedule``. From there, select ``New Task``

Add New Task

Once you do that, a new window will open. You can choose from several actions such as run this task: manually, immediately, on restart or recurring. In most of the cases you will probably want to use manually - that`s what I am going to use in this example.

Task Properties
Great, now we need to specify what to remove. Click on ``Add Data`` and another window named ``Select Data to Erase`` will open. As you can see there are several options to choose from such as ``Unused Disk Space`` or ``Recycle Bin``.
Select data to Erase
To keep things easier to understand, in this example I will choose a file located on my Computer.

Open file from My Computer
I will select that file and it will take me back to the previous window. Click on ``OK`` to confirm.

Select file to erase

It`s the same window but there is one exception. I can view the path of the data that it`s going to be deleted. I will click ``OK`` and it will be added on the main software interface. All I need to to is to perform a right-click and select ``Run Now`` and the erasing procedure will start.

Run Eraser Task

I have added a small file approximately 3 MB - this will work fast ( a couple of seconds ) even if I would choose a method that requires more time to complete such as Gutmann (35 steps). Here`s how it looks when it`s processing the operation.

Secure deletion of files in progress

If everything went well you should see the following confirmation inside of Eraser interface.

Deletion process completed

If I would want Eraser to permanently erase recycle bin files, I would return to his interface, select a ``New Task`` ( CTRL+N) and perform the same steps. Add Data, select ``Recycle Bin`` and ``OK`` 2 times.

Eraser steps to follow if you want to delete Recycle Bin content

Finally, I will be redirect to main software interface and I would just repeat the same thing. Right-click on the task and select ``Run Now`` - the files will be permanently erased.

Delete Recycle Bin content

Conclusion: If you need to prevent data recovery this is going to work - permanently and irreversible for everyone with one exception: government agencies. You can`t find a single evidence on the Internet that overwritten data has been recovered and still some people believe that government agencies can recover at least a part of the deleted data. I can tell you that this is one of the safest methods that can stop both software and hardware recovery for normal people. Perhaps a secret agency or people willing to invest millions of dollars in high technology equipment and human resources ``could`` ( theoretically ) recover some parts of deleted information or better said, overwritten. However, for normal people and even for others, deleted data that use a security level such as Gutmann algorithm will remain deleted forever.



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