Most computer users aren’t aware of how persistent the data on their computer really is. The truth is that placing files into the recycling bin and emptying it doesn’t really erase the files. Installing a new operating system or reformatting the hard drive will make files more difficult to recover, but they are still there if a determined or lucky thief knows how to look for and recover them.
When a file is created, space on the disk is used to store the file, and then the address of this space is stored by the operating system. The deletion actions of an operating system will destroy this address, but not bother with the actual contents of the file. In a pragmatic way, this makes sense – without the address stored, the are on the disk where the file used to be will be over-written by another file eventually – so there’s no pressing need to erase it now. Besides, users change their minds from time to time and might want a file back.
The solution is to use a different kind of deletion program. These are “block eraser” programs, so named because they erase whole blocks of hard drive data at a time. This means that the entire drive will be erased and over-written so that the files can not be retrieved at all. It also means that the operating system will be permanently erased, so this should only be done if you are completely finished using a hard drive.
A popular block erase program is Darik’s Boot and Nuke (DBAN – www.dban.org). It completely erases the contents of any and all hard drives that it can detect. Once you have a DBAN diskette or CD, using the program is fast and simple:
* Turn on the computer, booting from the DBAN diskette/CD. See notes below if needed.
* The DBAN application will load. It uses a text only interface, so you will enter all commands with the keyboard only.
* Press -Enter- to start DBAN in interactive mode. It will take a moment to load.
* It is advisable to leave all default setting in the Options menu. Instead, go to the Disks and Partitions menu.
* Use -J- and -K- to navigate to the hard drive you want to erase, and select it with the spacebar.
* Press F10 to start the erasure.
* Once DBAN is finished you will get a confirmation message “DBAN succeeded”
Instead of using a block erase program, many modern hard drives’ firmware also includes a utility for complete drive erasure called Secure Erase. This can also be downloaded for free (from http://cmrr.ucsd.edu/people/Hughes/HDDEraseWeb.zip). Secure Erase works faster than DBAN, but might require more technical knowledge. Also, depending on your computer manufacturer, their BIOS settings may or may not allow Secure Erase to run on the drives plugged into your computer (this is meant to prevent hackers or malicious software from erasing your drives).
The process for running Secure Erase is very similar to that of DBAN:
* Boot from a bootable disk, CD, or USB on which the Secure Erase application (HDDErase.exe) is stored.
* If you boot into DOS, you will be given a comman prompt. Type “hdderase” and press -Enter- to start Secure Erase.
* A text based interface will display the available disks and inform you of the options available for erasing each of them. Most of the time you will want to select “secure erase.”
Some computers may not automatically load from a CD. If this is the case, you will have to change the load settings in the computer’s BIOS.
* Restart the computer. As the computer is loading, it will go through several screens. Look for commands along the bottom of the screen that reads something like “
* In the BIOS screen, you will have several menus to choose from. The boot order information is usually under “Advanced BIOS Settings”.
* Depending on the BIOS of the computer, you will have a number of different options available. The important thing is that the “Primary Boot Device” is set to the device you are using. That is, select “CD” if you are booting from a CD. Some systems can even boot from a USB device.
* Save your changes and exit BIOS. The computer will restart with the new settings, now booting from your selected device.
By completely erasing the data on your hard drive, you can be sure that no personal or private information will be misused. If you must, physically destroying the disc is also a fast, secure method of file destruction.