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List:       gentoo-security
Subject:    Re: [gentoo-security] Secure deletion of files...
From:       Spider <spider () gentoo ! org>
Date:       2004-05-06 10:00:14
Message-ID: 20040506120014.3d046419.spider () gentoo ! org
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begin  quote
On Wed, 5 May 2004 20:04:44 -0400
Ryan Voots <simcop2387@yahoo.com> wrote:

> On Tue, 4 May 2004 09:54:36 +0200
> "Marc Ballarin" <Ballarin.Marc@gmx.de> wrote:
> > shred is not reliable on modern filesystems. Clever block allocation
> > algorithms, journalling and on-disk write-caches make secure
> > deletion from
> > userspace unreliable  (shred's man page lists even more examples).
> 
> i've actually thought about that problem and was wondering, since the
> clever file systems and such would probably not want to move the
> blocks around on every write, why couldn't you zero out the file
> backwards (i understand this could end up a buffering issue but i
> think that can be worked around) after that you just delete it like
> normal?

one word:
blockreallocation
(well.. *cough* ;)

modern harddrives are actually larger than specified, and use something
around 1Gb (perhaps more?)  to shuffle around "bad blocks" and damaged
sectors and do other black majjik.  

you cant even reach theese from software.

put simply: You can't delete things from your harddrive. You can only
reuse the space and hope for the best.

//Spider


-- 
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Tortured users / Laughing in pain
See Microsoft KB Article Q265230 for more information.
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