On 01/05/2016 03:00 PM, Fred Cisin wrote:
NSA has done substantial serious research on that and other recovery.
1) if the alignment of the head of the original recording and of the
overwrite head are not a perfect match, then there can be some residual
data somewhat off axis.
2) if the data was overwritten once, with a known pattern, then somebody
with sufficient resources and motivation can attempt to analyze the
noise, and determine "what, overwritten by a 0 could produce the noise
that we have here." Accordingly, there are guvmint standards of
MULTIPLE patterns to overwrite with to render such extreme techniques
unusable.
However, I will heartily agree that recovery ceases to be PRACTICAL.
I recall reading (back in the 90s, that various labs were fooling with
this wrt hard disks of the timeand that any success was extremely small
potatoes. i.e. maybe a kilobit per hour and not 100% by any means.
We have easier ways now, thanks to the Patriot Act. More personal.
When folks would ask me how to completely erase a hard disk, I suggested
that bashing it to junk using a good sledge hammer or running it through
a log chipper then burning the pieces was a good start.
On the other hand, simply shredding floppies isn't good enough. There
was an old "The New Explorers" program on putting floppies back together
and getting data. I know the people who did it--in one of the shots in
the background, you can see Anadisk running.
I suggest letting floppies soak for a week in a barrel of diesel, then
setting fire to them should do the trick.
The old maxim of "you don't know what you've got 'til it's gone" applies
to data recovery as well.
--Chuck
