On Wed, 27 Jul 2005, Mike McCarty wrote:
Damian Menscher wrote:
On Wed, 27 Jul 2005, Michael Hennebry wrote:
I think something like this will come close.
lots of random writes
tune2fs -O ^has_journal device
shred shreddees
tune2fs -O has_journal device
My first thought when seeing this thread a few days ago was:
remount as ext2; shred files; remount as ext3
I'm fairly certain that meets DoD standards.
DOD standard is probably beyond what I need. Umm, how
does one unmount/remount one's root?
Simplest method: modify your /etc/fstab to say ext2 instead of ext3,
then reboot. It will then mount it without using the journal. (The
method the other poster gave, of using tune2fs to remove the journal,
may or may not work on an ext3 filesystem mounted read/write.) After
you've wiped the data, change /etc/fstab back to ext3 and reboot.
Not sure why there's so much discussion here....
I think it's because there is a significant issue, and not much
real information.
Not much information here, perhaps. But there was a good discussion on
it on bugtraq just last week.
BTW, you will be amused to hear I wiped a drive for someone a few years ago
via the (wipe|shred) /dev/hda method. 25 passes of patterns and random
data. No way any government could get that data back. Doubtful
Presumably, you have never heard of the Watergate Tapes and the
"erased" tapes which were later recovered.
Accidental erasure with a single pass with non-random data to cover a
signal that is highly redundant is hardly a comparison. DoD standards
specify 7 passes (various patterns) to eliminate confidential data. The
state of Illinois requires 10 passes (they're just being silly). I'm
quite certain that 25 passes is extreme overkill. A single pass will
make the data unrecoverable to anyone with less than a few thousand
dollars. Two passes will make it unrecoverable to those with less than
$10,000. Three passes probably puts it at the NSA level. Anything
beyond that is probably a waste of time.
As I pointed out earlier, *my* interest is (almost) purely ethical.
How much is their data worth? Probably not that much, or they wouldn't
have let you take it home. So delete it to the point that it would no
longer pay to recover it. If it is no longer worth recovering, it has
been effectively deleted.
Damian Menscher
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