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How can I securely wipe disk drives?

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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:

  • Download DBAN.
  • Use DBAN to create a bootable DBAN CD, and then boot your computer using this CD.
  • At the boot: prompt, press Enter to start DBAN in interactive mode.
  • 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.
  • 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:
  1. If you see "[****]", the section of the disk you selected will also be wiped.
  2. If you see "[----]", you have already selected a section of the disk for wiping. Uncheck your selection and instead wipe the entire disk.
  • 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
Mac OS X has several built-in options for securely removing data:

  • To overwrite and delete files you've dragged to the Trash, from the Finder, select Secure Empty Trash.
  • For whole file systems, use the Disk Utility, which can be found in any of the following places:
  1. In the Applications/Utilities/ folder on your hard drive
  2. In the Recovery HD partition (Mac OS X 10.7 and later)
  3. On the installation DVDs (Mac OS X 10.6 and earlier) that shipped with your computer - In Disk Utility, choose the file system for which you want to securely remove data, and then select the Erase tab. To overwrite free space on the file system (i.e., space that may contain data for files deleted insecurely), click Erase Free Space.... To delete or overwrite existing files, click Security Options.

For individual files, use rm -P from the command line. This overwrites files three times before deleting them.

Category: 
Security