How Do I Zero My Hard Drive?

Zeroing your hard protects sensitive information without physically destroying the drive.

Whether you'll be selling your old hard drive or throwing it out, when the time comes for your next system upgrade, you'll want to be sure that your personal data doesn't fall into the wrong hands. Criminals who get hold of hard drives know exactly where to look to steal your identification and financial information. Merely formatting your drive leaves behind footprints that a tech-savvy individual can use to recover data. The only way to completely protect your data is to zero your hard drive.

Instructions

Linux Live CD

1. Download a Linux live CD and burn it to a disc. Live CD images allow you to run a full operating system from a CD or DVD. This particular operating system, Linux, has a number of useful disk utilities.

2. Remove all hard drives from your computer except for the one you will be erasing. This ensures that you will not accidentally erase data from another drive. Insert the live CD into your CD drive and reboot the computer. Follow any prompts that come up to configure basic settings like language and display settings.

3. Pull up a terminal by pressing "Ctrl-Alt-F1." Use the "ls" command to determine the name by which the system identifies your hard drive. This is typically "/dev/hda" or "/dev/sda." Use the following commands to determine which name is being used:

   ls /dev/hda*

   ls /dev/sda*

   The command that does not produce an error message is the one that identifies your drive. In the same terminal, use the "dd" command to write zeroes to the entire disk:

   dd if=/dev/zero of=/dev/sda bs=512 count=1

   Replace "/dev/sda" with "/dev/hda" if appropriate. This step may take some time to complete, especially if you have a large hard drive.

4. Verify that your disk has been properly zeroed by pulling up a hex editor and looking at the data on the drive you just wiped. Type in:

   vi /dev/sda

   :%!xxd

   Replace /dev/sda with /dev/hda if appropriate.

   You are now looking at the data on your hard drive. Each sector should read "00." Quit the hex editor by pressing "Esc," then typing ":q"; press "Enter."

DBAN

1. Download DBAN (see References) and burn it to a CD. Remove all of your hard drives except for the one you will be erasing. This will prevent unintentional data loss.

2. Insert the DBAN CD into your disk drive and reboot your computer. Select the "Quick Erase" algorithm. This will simply fill your drive with zeroes. If you would like a little more security, you can instead select the DoD 5220.22-M algorithm. This is a Department of Defense security standard which will complete zero your drive, then fill the drive with "1"s, then fill the drive with random data.

3. Verify that your data has been erased by removing the DBAN CD and rebooting your computer. If it does not start up, you are in good shape.

KillDisk

1. Download KillDisk (see References). The free version of this software contains everything you need to zero your drive. Burn it to a CD, insert it into your drive, and reboot your computer.

2. Select the disk you wish to erase, then press "F10." Press "Enter" to select a custom wipe method. Select "One Pass Zeros," then press "Enter." Select the "Confirm and Wipe" option using the arrow keys, then press "Enter" again. Type in the security code when prompted, and then press "Enter" to begin zeroing your drive.

3. Remove the CD from your disk drive and turn on the computer. Your computer should not boot up properly, confirming that your data has been successfully erased.

Tips & Warnings

• Make sure to properly back up any data you wish to keep. Without special forensics equipment, all data will be irrecoverable after this process.

References

• Delete Files Permanently: Wiping Schemes
• die.net: dd Linux Manpage
• Darik's Boot and Nuke: DBAN Documentation
• Active@ KillDisk: Active@ KillDisk User's Guide
• KP Solutions: How to edit HEX file in VI?