Re: Wiping a drive: /dev/zero or /dev/urandom better?

["Craig Wright" <craig.steven.wright () gmail com>]

The simple answer is that it does not matter. A single wipe (done
correctly) will make it infeasible for ANYONE (even governments) to
recover information.

If you go to the page:
http://seclab.cs.sunysb.edu/iciss08/program.html

There is a paper being presented:
"Overwriting Hard Drive Data: The Great Wiping Controversy"
Craig Wright, Dave Kleiman and Shyaam Sundhar R.S..

The paper details this issue. A few people have seen it already. It
will be available (published) in Dec in the Springer Verglag LNCS
series. We hope that this paper will finally put some of the silly
myths to rest.

Regards,
Craig Wright GSE-Malware, GSE-Compliance

On Wed, Oct 15, 2008 at 2:39 AM, Adriel Desautels <adriel () netragard com> wrote:
> use dban, it works wonders.
>
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>
> JW wrote:
> > I've got a theoretical question: when wiping a drive (I'm talking about Linux
> > here), which of the following is more: fill the drive with data
> > from /dev/zero or /dev/urandom?
> >
> > I ask because I often see people suggest something like the following for
> > wiping disks:
> >
> > cat /dev/zero > /dev/hda
> >
> > (and of course do it multiple times)
> >
> > I got to thinking that (if you are really paranoid) it would probably be
> > easier for "the bad guy" to recover original data if you use /dev/zero
> > because it's so uniform, the "bad guy" can just look for anything other then
> > zeros - if it's not zero, it's data.
> >
> > Which would imply that overwriting the data with /dev/urandom or /dev/random
> > would be more secure.
> >
> > But I don't know enough about the internals of hard drives to know if it
> > really matters or not.
> >
> > For clarity I'll point out that I'm not talking about wiping files in the
> > filesystem, I'm talking about wiping whole disks - I guess you'd say "at the
> > block level".
> >
> > What do the resident experts here think?
> >
> >       JW



-- 
Dr. Craig S Wright GSE-Malware, GSE-Compliance, LLM, & ...