[TriLUG] Disk Wipers
bitmage at pobox.com
Thu Aug 23 16:09:56 EDT 2007
On Thu, Aug 23, 2007 at 04:00:56PM -0400, Warren Myers wrote:
> the only drawback to dd is that you have to run it a bunch of times to get
> "good" overwriting...
This is only true if you expect extraordinary measures to be taken against you.
Once you've written a zero to a spot on the drive, the drive will return a zero
whenever that spot is read. To do otherwise would be a failure of the drive to
return valid data.
Overwrite the whole platter with zeroes once, and there is no way short of
replacing the drives electronics with custom hardware that you're going to get
the old data back. Or opening it up and attacking it with a magnetic force
If you think that governments and three-letter agencies are after your data,
then by all means smash the drive and boil it in acid. But they've probably
already installed a keylogger on your system...
Otherwise a single zero-overwrite will do fine. Or you can use Secure Erase
from http://cmrr.ucsd.edu/people/Hughes/SecureErase.shtml which calls the
internal secure-wipe routine present in modern HD's.
Be it thy course to busy giddy minds
With foreign quarrels; that action, hence borne out,
May waste the memory of the former days.
Henry IV, Part 2
Brian Daniels bitmage at pobox.com
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