Phil Lewis wrote:
> On Thu, 2009-02-26 at 14:59 +0000, David Greaves wrote:
>> Err, that would be the point...
>>
>> And given that your plot would even work, how many spods on eBay have access 
>> to
>> a magnetic force microscope?
>>
>> Obviously the word spods includes BBC reporters (note, not "journalist")
>> incapable of entering
>>   "wiped disc recovery scanning electron paper"
>> into Google and getting as the second hit:
>>   http://sansforensics.wordpress.com/2009/01/15/overwriting-hard-drive-data/
>>
>> Which makes a mockery of the whole thing (as do any number of other 
>> references
>> that are not obtained from companies making a living from BS).
> 
> Then there is the paper (read the epilogue especially) which debunks
> this above linked article by the Author (Peter Gutmann) on who's
> out-of-date material they based it!! 
>
> It was published in 1996 and the epilogue was written this year as a
> strong rebuttal to the sansforensics article.
> 
> http://www.cs.auckland.ac.nz/~pgut001/pubs/secure_del.html
> 
> Well worth a read and very insightful...

I read this some time ago and actually that was the link I was looking for -
sadly my search-fu let me down - thanks for sharing.

My reading of the epilogue is that they don't debunk it so much as critique it.
I think the main point of the sansforensics article is the statistical analysis:

"Therefore, there is a chance of correctly choosing any bit in a selected byte
(8-bits) – but this equates a probability around 0.9% (or less) with a small
confidence interval either side for error."

In any case the summary of the 'epilogue' is:

"Any modern drive will most likely be a hopeless task, what with ultra-high
densities and use of perpendicular recording I don't see how MFM would even get
a usable image, and then the use of EPRML will mean that even if you could
magically transfer some sort of image into a file, the ability to decode that to
recover the original data would be quite challenging."

ie: Even with super-advanced tech like MFM it is not feasible to recover data
from a wiped drive - although secret squirrel level security people may be nuts
enough to try.

So I'm not sure how it classes as a "rebuttal" when the conclusion is the same?
(Although I do agree that they disagree on the technique used to reach the
conclusion).

By all means get the reporter to attempt this technique - the paper does say:
"Even for a relatively inexperienced user the time to start getting images of
the data on a drive platter is about 5 minutes."

*That* would be a fascinating story no matter what the outcome!

Of course, finding an MFM that the owner will let you "have a go" on may be
trickier... maybe the spods buying your drives on eBay know something we don't?


Oh, my wife noticed the story is no longer linked to on the technology page -
and they do tend to hang around normally. Maybe someone is paying attention :)

David

-- 
"Don't worry, you'll be fine; I saw it work in a cartoon once..."
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