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This program is intended to be used in conjunction with SecureDelete to securely remove any data that might be left behind on your disk in its "unused" sectors (ie. sectors that are not used by existing files).

This is to guard against the possibility that someone with a disk editor might view your unused sectors and recover the contents of files that were previously there (but have since been deleted insecurely).

It does this by opening a file whose name you choose (the name isn't important), and then writes to it continuously until the disk fills up. It then writes another six passes of data (first pass, all one bits, other passes random data), to make sure the data can't be recovered. It then deletes this file, to free up the disk space again.


Before running this program:

  1. Delete any unwanted files, particularly "backup" files (eg. xxx.BAK) which contain sensitive data.
  2. Empty your "recycle bin".
  3. Make sure other programs are not running - if the disk fills up they may get excited.
  4. If you have more than one logical drive (eg. C, D, E) then you will need to run this program on each drive. It will only fill up the drive that it is running on.
  5. After using this program, delete any further files that contain confidential information with SecureDelete (if they are no longer wanted, of course!)
  6. You can press Ctrl+C to abort the operation, and the program will delete (ie. remove from the disk directory) your nominated file. However if the program is aborted before finishing normally then the disk is not as secure as if it had.


On the command line, specify the name of the file you want created. It will default to \UNUSED.DAT


This program does not pretend to solve all of your security problems on your PC. You are recommended to read some of the very good books on computer security and encryption to further your understanding of those issues.


To download, click on the "downloads" button at the top of this page.


This program is supplied free of charge. It is copyright 1998 by Nick Gammon. Source code is available from the downloads area.

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Page updated on Wednesday, 15 December 2004