Re: Wiping hard drives - [OT]
On 20/09/11 00:27, Aaron Toponce wrote:
> On Sat, Sep 17, 2011 at 08:59:14AM +0200, Ralf Mardorf wrote:
>> If you want to be safe, you need to overwrite the data several
>> times,
>
> Have anything to back that up?
Try eating your own dog food - the citation in the wikipedia link (made
no more official by the circuitous url shortening) contradict your own
statements.
> If you're using drives that used the
> old MFM or RLL encoding schemes, and had massive space for bits per
> linear inch, then sure, but on today's drives, with perpindicular
> encoding, and the extremely dense bit capacity, going more than once
> is silly.
Magnetic fields decay - regardless of track layout. I don't know where
Ralf got the laser idea from - I'm only familiar with side-scanning
electron microscope techniques. Used to recover unmelted segments or S11
platters - and also to recover data from disks deliberately overwritten
many times in a futile effort to erase evidence.
>
>> 'shred' does delete data several times. We hardly are able to
>> recover data that one time really was deleted at home, but CSI is
>> able to do this
>
> [citation needed]
>
<snipped>
>
> You may want to read this, as well as the references the article
> links to:
>
> http://goo.gl/5QG4U
I'd suggest you actually *read* the material you reference. Those
conclusions are backed up in more detail for the referenced articles...
Note especially (the ones I'm familiar with):-
http://www.oregon.gov/DAS/OP/docs/policy/state/107-009-005_Exhibit_B.pdf?ga=t
http://www.dsd.gov.au/publications/Information_Security_Manual_2010.pdf
Let me summarize it for you - multiple, random. overwrites is considered
a minimum requirement for data security *onsite* *before* being taken
(by secure) methods for high-temperature destruction.
Some sites have a special device that fires a bullet through hard drives
scheduled for destruction - somehow that has led people to ignore the
"scheduled for destruction" bit and focus on the bullet. Damaging (by
bullet, degausser, or *multiple* overwrites) is an onsite measure take
prior to shipping to a smelter (in case the shipper loses a drive/tape).
The same procedures apply to tapes - 1 minute of wipes across the noisy
3M degausser before being put in the locked bins to be shipped for high
temperature destruction. Not out of uninformed paranoia - but because
data can be recovered and information can be reconstructed.
Are the same procedures necessary for home users/SMEs? No.
Does that make false statements true? No.
>
> Claiming that you can recover data after a single pass of zeros on
> today's spinning platters is urban legend.
Many companies make their living from that "urban legend".
The magnetic fields decay over time (anytime) - so recovery is always
possible provided the time, equipment, and expertise is available.
It would be more accurate to say - it's very unlikely anyone has the
equipment, skills, and motivation to recover data from a drive that has
multiple layers of data overwritten - than to make patently, and
demonstrabley absurd statements like you have.
> I guess
There's the problem.
> if you like wasting your time, go for it. I've got better things to
> do than do several passes on a 2TB SATA disk, running at 30MBps, and
> I can sleep at night knowing that no one will get access to the
> data.
>
<snipped>
The vast majority of the time your single wipe will be enough to protect
your data - though it's probably quicker, and simpler to break off the
point of a pin in the breather hole and/or damage the power connectors.
There's probably no need to shred old DVDs and CDs either.
Cheers
--
"Always question authority, and demand the truth."
— Bill Hicks
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