Erik Norgaard norgaard at
Thu Jan 20 12:22:41 PST 2005

John wrote:
> On Thu, Jan 20, 2005 at 03:52:29PM +0100, Anthony Atkielski wrote:
>>Colin J. Raven writes:
>>CJR> I always thought that formatting/fdisk'ing twice completely erased
>>CJR> *permanently* whatever had been on the disc.
>>Information can be recovered from disks even after a dozen or more
>>overwrites.  The data is never safe with the platters intact.
> Good gosh, what are you people doing on your machines - designing
> weapons systems?
> What what you are all saying is TRUE, it is not TRIVIAL.  After
> a "security erase" on a disk drive, or a full over-write, it
> takes increasingly sophisticated levels of lab equipement and
> environments to do the sort of things that you are describing -
> including disassembly and clean-room stuff.  In otherwords, someone
> has to be willing to invest at least a few hundred dollars (if it
> has simply been overwritten) to several THOUSAND dollars to do
> these sorts of recoveries, and some patience, because it takes
> TIME, and often, like million-year-old DNA, there are gaps that
> need to be reconstructed.
> What do you folks have on your hard drives that is worth thousands
> of dollars and weeks of time for someone to recover?
> If it was as easy as you describe, we'd rarely need backups.  Your
> disk drive crash?  Oh, just bring it to the local recovery service
> and they'll get all your data back for $9.95.  NOT!!!!

Sorry, this spun of from my initial post about destroying harddrives 
before donating old machines. Many larger companies have a fixed 
upgrading schedule, a pc lives 3 years. But for many people, schools and 
developing countries such a pc is absolutely not dead.

In most cases the average home pc will not be worth throwing that amount 
of money to recover data, and hence nor will it be worth to go through 
all that trouble to destroy data.

However, it has happened that pc's donated (this was the topic) to 
schools or to developing countries by companies or government institu- 
tions still contained confidential data, personal data or industrial 
secrets, that were recovered and revealed against the will of the 
original owner.

My consideration was that it might be cheaper to donate such pc's with 
new harddrives rather than go through the trouble to overwrite the disk 
to destroy data properly.

If you are paranoid about your home pc you keep secret data on an 
encrypted partition. One should however, not neglect that most home pc's 
contain confidential or personal information such as credit card 
numbers, passwords and embarrasing photos.

In case you didn't find the top of where this discussion span of, I hope 
this clears things up.

Cheers, Erik

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