How can I securely wipe disk drives?

When erasing sensitive data, always make sure that the data cannot be recovered. A few ways to do this include Darik's Boot and Nuke (DBAN), or various options within Mac OS X.

Using DBAN

To securely wipe a disk drive using DBAN:

1. Download DBAN.
   
   
2. Use DBAN to create a bootable DBAN CD, and then boot your computer using this CD.
   
   
3. At the boot: prompt, press Enter to start DBAN in interactive mode.
   
   
4. Press  M  (Method). On the "Wipe Method" screen, use the arrow keys to navigate to your preferred wiping method (e.g., Quick Erase [one pass], DoD Short [three passes], or DoD 5220.22-M [seven passes]). Press the Spacebar to save your selection and return to the Disks and Partitions menu.
   
   
5. If only one disk is present in your computer, select the top option that appears in the Disks and Partitions menu, and then press the Spacebar. The selection box will display "[wipe]" to indicate what will be securely erased:
   
   
   • If you see "[****]", the section of the disk you selected will also be wiped.
   • If you see "[----]", you have already selected a section of the disk for wiping. You should uncheck your selection and instead wipe the entire disk.
   
   
6. Press the F10 key to begin the secure erase process. As soon as you press F10, data erasure will begin.

The "Statistics" box in the top right corner of the screen will display an estimate of the time remaining on the disk wiping process.

Using Mac OS X

If you have a Macintosh computer running Mac OS X, you have several built-in options for securely removing data:

• For files you've deleted by dragging to the Trash, from the Finder, select Secure Empty Trash. This will overwrite and delete files in the Trash.
  
  
• For whole file systems, use the Disk Utility, which can be found either in the Applications/Utilities/ folder on your hard drive, or on the system CDs that shipped with your computer. Select the file system for which you want to securely remove data, and then select the Erase tab. On the Erase pane, the Erase Free Space... button lets you overwrite free space on the file system (i.e., space that may contain data for files deleted insecurely). The Security Options button allows you to delete or overwrite existing files. Each of these buttons gives you the option of overwriting files 1, 7, or 35 times.
  
  
• For individual files, use rm -P from the command line. This overwrites files three times before deleting them.

For more information, see the UISO article about Securely Removing Data.

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