Wiping data from drive question

kony wrote:

> We're not talking about a short glimpse, rather someone who
> is experienced and _trying_ to recover the data with the
> correct equipment.

You may or may not notice that just signal evaluation in a normal read
process today is just about recover. If there were any significant
redundancies left, we'd exploit them to store more data.

Sebastian Gottschalk

kony wrote:

> Now, if you were to continually overwrite the same areas,
> over and over again with zeros, this would work better, but
> not ideally, and why would one want to do that several more
> times than it would take to write randomly? There would be
> no reason to do it.

This is just bullshit argumentation.

As the rest signal is independent from the new data, there's essentially
no difference with what exactly you overwrite.

Sebastian Gottschalk

On Tue, 13 Jun 2006 22:06:43 -0500, "Steven L Umbach"
<> wrote:

>Not impossible but very unlikely without access to the proper equipment and
>having the necessary skills. It may take a little longer but it is a good
>idea to erase to DOD standards or better which most erase programs will
>allow you to do. With XP Pro or Windows 2003 you can use cipher /w to do a
>decent quick job of overwriting data. A sledge hammer and bucket of
>sulphuric acid is probably the most secure solution for permanent
>destruction of data but should not be attempted by amateurs.

I often hear of these excessive methods and just pass it off
as overkill but effective.

It isn't really effective at all. If one has done the
random-overwrite the data is already gone- end of story.
If one has not done the random overwrite and intends to
remove the drive for later destruction, it is only
subjecting the drive to more potential for it to fall into
the wrong hands, hands that would obviously be willing to go
to extremes to get it... if they're a problem making
ultimate destruction of data important in the first place.

Attended and immediate multiplass overwrite at the moment
the data is wished destroyed is the most safe method. Any
extra time spent physically destroying the medium is
probably better spent just standing around, watching those
around you for suspicious activity.

kony

On Thu, 15 Jun 2006 02:04:17 +0200, Sebastian Gottschalk
<> wrote:

>kony wrote:
>
>> We're not talking about a short glimpse, rather someone who
>> is experienced and _trying_ to recover the data with the
>> correct equipment.
>
>You may or may not notice that just signal evaluation in a normal read
>process today is just about recover. If there were any significant
>redundancies left, we'd exploit them to store more data.


In a cheap-to-make, mass produced drive this would be true.
In a spare-no-expense, recover-valuable-data scenerio, the
minor differences are what is important.

kony

On Thu, 15 Jun 2006 02:06:09 +0200, Sebastian Gottschalk
<> wrote:

>kony wrote:
>
>> Now, if you were to continually overwrite the same areas,
>> over and over again with zeros, this would work better, but
>> not ideally, and why would one want to do that several more
>> times than it would take to write randomly? There would be
>> no reason to do it.
>
>This is just bullshit argumentation.
>
>As the rest signal is independent from the new data, there's essentially
>no difference with what exactly you overwrite.


Every single article on the subject disagrees with you.
Read a few.

kony

kony wrote:
> On Thu, 15 Jun 2006 02:04:17 +0200, Sebastian Gottschalk
> <> wrote:
>
>> kony wrote:
>>
>>> We're not talking about a short glimpse, rather someone who
>>> is experienced and _trying_ to recover the data with the
>>> correct equipment.
>> You may or may not notice that just signal evaluation in a normal read
>> process today is just about recover. If there were any significant
>> redundancies left, we'd exploit them to store more data.
>
>
> In a cheap-to-make, mass produced drive this would be true.
> In a spare-no-expense, recover-valuable-data scenerio, the
> minor differences are what is important.

A very optimistic estimation gives that you can recover bits with a
median certainty of 50.4% correctly. And random overwrites don't change
anything about that,

Sebastian Gottschalk

kony wrote:

>> As the rest signal is independent from the new data, there's essentially
>> no difference with what exactly you overwrite.
>
> Every single article on the subject disagrees with you.
> Read a few.

Strange enough Mr. Gutmanm fully agrees with me. I haven't found any
scientific article disagreeing. Can you point me to one?

Sebastian Gottschalk

In article <>, says...
> kony wrote:
>
> >> As the rest signal is independent from the new data, there's essentially
> >> no difference with what exactly you overwrite.
> >
> > Every single article on the subject disagrees with you.
> > Read a few.
>
> Strange enough Mr. Gutmanm fully agrees with me. I haven't found any
> scientific article disagreeing. Can you point me to one?

I would suggest that you both read the following:
http://csrc.nist.gov/publications/dr...-Feb3_2006.pdf


--


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Leythos

On Thu, 15 Jun 2006 08:44:23 +0200, Sebastian Gottschalk
<> wrote:

>kony wrote:
>
>>> As the rest signal is independent from the new data, there's essentially
>>> no difference with what exactly you overwrite.
>>
>> Every single article on the subject disagrees with you.
>> Read a few.
>
>Strange enough Mr. Gutmanm fully agrees with me. I haven't found any
>scientific article disagreeing. Can you point me to one?

You don't bother to reference this "Gutmanm" and yet I am
supposed to find articles for you? It is well known, the
WHOLE PURPOSE of the random overwrite strategy used
countless times by anyone, anywhere (everywhere).

I suppose you mean Peter Gutman, but are you referring to
his work a decade ago (when HDD densities were a fraction of
what they are now) or something more recent? You need to
provide a specific quote, WITH the context, if you want to
claim Gutman is in agreement with what you claim TODAY...
because back then he was of the opinion that the goal was to
flip the bits back and forth unpredictably, in a random
pattern, not pseudo-random and NOT all zeros as you suggest.

kony

kony wrote:

> It is well known, the WHOLE PURPOSE of the random overwrite strategy
> used countless times by anyone, anywhere (everywhere).

It is well known to the uninitiated, but not in any scientific context.

> I suppose you mean Peter Gutman, but are you referring to his work a
> decade ago (when HDD densities were a fraction of what they are now)
> or something more recent?

Read Gutman's article and try to understand the content. He told that
his ideas exactly apply to any modern drives and about any future drive
with the same technology, and that only special cases of old, really
low-density drives must be considered carefully.

> You need to provide a specific quote, WITH the context, if you want
> to claim Gutman is in agreement with what you claim TODAY... because
> back then he was of the opinion that the goal was to flip the bits
> back and forth unpredictably, in a random pattern, not pseudo-random
> and NOT all zeros as you suggest.

No. He was the opinion that doing so is absolutely unnecessary and just
added for safety, which also applies to the large number of passes. Now
RTFA.

Sebastian Gottschalk