How To Erase Your Hard Drive Like A Secret Agent

If you’re going to retire your old PC, it’s only natural that you’d want to delete all of your personal data from it. Most people will search out what personal files they can, and delete them with a simple push of the delete key. Unfortunately, when you delete a file in Windows, the operating system only removes the reference from the master file table, leaving the actual data on the drive.

If your PC were a book and your files were chapter 9, Windows delete is like removing chapter 9 from the index, but leaving the pages in tact. The data may not look like it’s there to the average user, but until you write over that space, anyone with a free file recovery tool and access to your PC has a chance of recovering your files. That’s why if you’re going to retire a PC, the best thing that you can do is to completely scrub your hard drives by overwriting every last block with multiple passes of random data. Governments, corporations, and paranoid geeks have done this for years, and in this age of identity theft, there’s no reason that you shouldn’t either.

Don’t start sweating now. You don’t have to have a room full of mainframes or know anything about Star Trek to scrub your drives clean. With a free piece of open source software and the short set of instructions below, you can ensure that your private data will be banished to the land of wind and ghosts, which is way beyond the reach of anyone without a clean forensics lab and some incredibly skilled data recovery personnel.

Warning: I’m going to spell this out on the off chance that you are skimming. Creating this disc and using it on a PC or Mac will overwrite everything on the hard drive. You won’t be able to surf the internet, chat, play games, balance your checkbook, or update your Facebook profile on it anymore because it is not going to boot. This is not a way to clean spyware or securely empty the recycle bin. This is a method to use only when a hard drive is going to leave your hands and you don’t know whose hands it may fall into. Ok? Back to skimming.

How To Securely Erase Your Personal Data Using DBAN

  1. Download DBAN. You can download the installer to create a floppy disk, or you can download the ISO to use with your favorite CD burning program to create a boot CD.
  2. Insert the CD or floppy you created in step 1 and start the machine. If your PC boots normally and not into the DBAN program, your PC doesn’t include the floppy or CDROM drive in the boot sequence. You need to go into the bios and change the boot order to include the drive that includes your DBAN disk.
  3. Press [enter] when you arrive at the Darik’s Boot And Nuke splash screen to start DBAN in interactive mode. This will take you to the drive selection screen.
  4. Select the drive(s) you want to erase using the arrow keys and space bar.
  5. Press M to set the erase method. There are six choices, including standards from the Department of Defense and the Royal Canadian Mounted Police, but most are rated only medium security options. The only two that are rated high security are the Gutmann method and the PRNG Stream. The Gutmann method does 35 passes of data, but it takes much longer and provides no extra benefit over the PRNG stream on modern drives.
  6. Select PRNG Stream by using the arrow keys and space bar.
  7. Press R, [backspace], 8, [enter] to set the number of rounds to 8. Most of the methods only use one round and multiple passes, but because the PRNG Stream only makes 1 pass, we have to set the rounds to 8 to ensure a high security wipe. You should now see rounds set to 8 at the top of the main screen.
  8. Press [F10] to start the wipe, and walk away for a while because properly scrubbing your personal data off of a hard drive can take several hours to complete.

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