Secure deletion of files in a directory

[David Shaw]

On Tue, Jun 15, 2004 at 06:25:06PM +0200, Albert wrote:
> Am Dienstag, 15. Juni 2004 17:39 schrieb David Shaw:
> 
> Thanks David!
> 
> > On Tue, Jun 15, 2004 at 04:56:05PM +0200, Albert wrote:
> > > I have to return a new hard drive in warranty and to delete a
> > > lot of directories which contain private data. Unfortunately
> > > the data of S.M.A.R.T are erased too, if I use badblocks -w to
> > > overwrite the _whole_ drive.
> > >
> > > I know there is a possibility to shredder a file with gpg, but
> > > not a directory. What do you recommend?
> >
> > GnuPG does not have a file shredder.  It is not possible to write
> > such a thing to be portable to as many platforms at GnuPG runs
> > on.
> 
> I use SuSE 9.1 and when I install KGPG there is an option to install 
> a shredder (Reißwolf, german) and it looks like it works.

SuSE is Linux.  GnuPG runs on Linux, various BSDs, Windows, RISCOS,
VMS, etc.  A shredder that works on one is likely to not work on
another.

> > I'd look at "shred", but keep in mind the caveats the author
> > gives in the man page.
> 
> shred doesn't work with directories and has problems with ext3 and 
> reiser. Any other ideas? Are you all returning your harddrives with 
> files on it :-)

As I said, keep in mind the caveats the author gives.  He says that it
doesn't work with journaling filesystems.

You must decide your paranoia level.  If it is high enough, you
*don't* return hard drives once they have data on them.  Most people
are content with overwriting the data a few times.  Let's put the
problem into perspective : not many people are concerned with very
well funded adversaries using magnetic force microscopy.

David