SHRED for EXT3?

Mike McCarty mike.mccarty at sbcglobal.net
Thu Jul 28 00:28:30 UTC 2005


Damian Menscher wrote:
> On Wed, 27 Jul 2005, Mike McCarty wrote:
> 
>> Damian Menscher wrote:
>>

[snip]

>>> 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.

Thanks, that's useful info.

>> 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 

Whether it was accidental seems to be a debatable point :-)
Whether it was single pass *also* seems to be a debatable point :-)
I happen to remember some of the debate.

C Language source files are significantly non-random data.

Are you an expert in data recovery or data obliteration?

[snip]

> 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.

At a guess, it has over 2000 man years into it. It is in a very
competitive industry (health care related).

Mike
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