Formatting your hard drive does not securely remove old data; any hacker with a little bit of knowledge could retrieve data from the drive. Writers from CNET, MakeUseOf and Geek Squad all agree that nothing beats Darik’s Boot and Nuke for securely erasing data from hard drive. If you have an SSD, Parted Magic offers a secure erase tool that works specifically with drives that use wear-leveling. A third option is to use the "wipe" command from an Ubuntu live disc. All three tools overwrite the hard drive with random ones and zeros to destroy the old data.

Darik's Boot and Nuke

Step 1

Download the DBAN ISO file from the DBAN website. Do not unzip or extract files. An ISO file is a disc image, and it must be burnt to a CD in order to function.

Step 2

Insert a blank CD into the drive; the ISO file is about 15 MB, so using a blank DVD is overkill, though it will work if that is all you have on hand. Double-click the ISO file in Explorer and select the disc burner to initiate the burn.

Step 3

Reboot the computer when your CD finishes burning. The DBAN software runs entirely from CD, allowing you to make changes to all aspects of your hard drive. DBAN has an old-school white text on a blue background and is controlled entirely by keyboard.

Step 4

Type "autonuke" to run DBAN's default erasure settings. If you want to run more than one pass to ensure that your data is completely unrecoverable, press "F3," then "M" to choose how you want the data erased. Many users select "DOD Short" to have DBAN run three passes of random ones and zeroes. Press "F10" to begin the process. It takes several hours to completely wipe a hard drive with more than one pass.

Parted Magic

Step 1

Download Parted Magic; it is available for purchase on the Parted Magic website. When the ISO download is complete, burn it to a CD or load it onto a bootable USB drive with a program like Unetbootin.

Step 2

Reboot your computer with either the CD or USB drive inserted. The media will boot into the Parted Magic system, which uses a version of Linux as a desktop environment. When prompted in the start-up menu, run with default settings.

Step 3

Click the menu icon in the lower left corner. Go to "System Tools" and select "Erase Disk."

Step 4

Choose "Internal: Secure Erase command writes zeroes to entire data area." Click "Continue," then select the disk you want to erase; Parted Magic shows a list of all hard disks connected to the system.

Step 5

Enter the password for drive when prompted if your drive has a password; if it does not, enter "NULL." You will be asked to confirm that you want to erase the disk. Click "Yes."

Ubuntu Live Disc

Step 1

Download the most recent Ubuntu release. When the ISO file is done downloading, either burn it to a blank CD or create a bootable USB drive using Pen Drive Linux's USB Installer, as recommended by Ubuntu.

Step 2

Reboot the computer with either the CD or USB drive inserted. This will boot you into a version of Ubuntu that runs from the removable media; it does not make any changes to your computer's operating system or settings.

Step 3

Click the network icon in upper right corner and connect to the Internet, or plug in an Ethernet cable if your computer does not use wireless. When the Internet is connected, press the Ubuntu icon on the side dock and type "Ubuntu Software Center." Select it when it comes up.

Step 4

Search for "wipe" in the software center; the first result should be the correct entry, called "Secure file deletion." Click "Install."

Step 5

Open the terminal and enter "sudo fdisk -l" to see a list of the currently connected drives, including internal hard drives and USB drives. The device is labeled in the format of "/dev/sda1" with some variations; for instance, USB devices may be listed as "/dev/sdb1." Identify which drive to securely erase if more than one drive is present in the machine. Windows drives will show the file system as "NTFS," at the end of the line.

Step 6

Enter "sudo wipe /dev/sda1" where the device label reflects the one used for your hard drive. You will be asked to confirm; type "yes." The terminal will begin the wipe, showing what sector it is on and how long the wipe will take. It may take several hours, depending on the size of your drive.