Eraser – Recommended File Shredding Tool Guideline
What is Eraser?
Eraser is file shredding tool that allows you to completely remove data from your system by overwriting it several times, thus sanitizing (sometimes referred to as shredding) the data and making it unrecoverable.
Why use Eraser?
To ensure confidentiality, it is a good idea to use a file shredder to permanently remove data from your system. Similar to shredding a paper document, when you shred a file on your system, it cannot be recovered.
Normally, when deleting a file from your system, the space that the data occupies is simply marked as available for the system to use. The file itself is removed from the directory list, but the actual data is still on the physical disk. Eventually, during normal use, this space will be overwritten, but in the meantime it can still be recovered using special utilities and forensic tools.
How does it work?
File shredding works by overwriting this space with random data. For sensitive information, it is recommended this data be overwritten several times. The Department of Defense standard (DOD 520.22) is three times.
How do I install Eraser?
Run the download file. The default options are fine, so click “Next” until the setup is complete.
How do I use Eraser?
The easiest way to use Eraser is to find the file you wish to delete in Windows Explorer. Right-click the file, then click the “erase”. Click “yes” to confirm. The file is now securely shredded and CANNOT BE RECOVERED. Afterwards, it will show a summary dialog box.
What else can Eraser do?
The main Eraser program can be found by clicking Start -> All Programs -> Eraser -> Eraser. There are several options, including scrubbing the free space on your drive to ensure that old deleted files are securely deleted. It can run scheduled erasure of particular data at regular intervals. There is also an On-Demand option in which you can drag and drop files into Eraser, then erase them all at once as a task item.
Can I remove Eraser when I’m done?
Of course, Eraser can be removed if you no longer have a need for it. The files that were securely shredded will still be gone.
When I erase a file, is it really gone?
Yes, when you use Eraser to securely delete a file, it truly is gone from the physical media. Unless there are copies left in other places (email, USB drives, CD), when using Eraser, the file is unrecoverable.
Can I get it back if I erased it by mistake?
No, once you securely delete a file using Eraser, it is gone and cannot be recovered. Unless of course there is a copy of the file somewhere else.
What if I need help?
In the Eraser application itself, after going to Start -> All Programs -> Eraser -> Eraser, there is a Help menu item if you require further assistance.
What are the other erasing methods?
There are three basic methods or theories of securely wiping data.
- The Gutmann method is based on Peter Gutmann’s paper “Secure Deletion of Data from Magnetic and Solid-State Memory”. He uses 27 different pattern passes used in random order to overwrite the data. Eraser also uses four passes of its own random data (generated using a secure formula) before and after, making a total of 35 passes!
- The Pseudorandom Data method uses an algorithm called the ISAAC to generate cryptographically strong pseudorandom data which is then used to overwrite the data. The number of passes can be user defined but the default is 1.
What is the best method to use for data wiping?
That depends on the data being erased. The most secure is the Gutmann method, but this is also the slowest method. For everyday use, the default pseudorandom method is fast and should be just fine. NOTE: For very sensitive information the Gutmann method would be preferable.