Mike Bell wrote:
The whole point of multiple write passes is that the physical head does not
write a track at the same exact physical location every time. With the
right equipment ( disk manufacturers and data recovery experts have it), you
can center the read head off to the side of the track, and read a value from
a previous write. The accuracy of the read depends on the normal your
mileage may vary factors, how long the previous value was there , where the
head was previously centered (within the limits of being able to read
correctly) etc. If you write random bit patterns, multiple times ( and
different bit patterns on each pass), then the difficulty of extracting the
previous data increases. How much the difficulty increases is known by the
people who do this for a living (NOT me).
I read about it approx. 5 years ago, so it's not new for me.
I understand why multiple passes are better than single pass, but still
have no aswer how many times is good enough. Otherwise someone (official
entity) could say "999 times". Or 9999 times. Or 99999 times. Everyone
would agree the more is the better - from security point of view.
So, should we overwrite 15 times or 999 times ? Please *justify* your
answer. <vbg>
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Radoslaw Skorupka
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BRE Bank SA
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Wedug stanu na dzie 01.01.2008 r. kapita zakadowy BRE Banku SA wynosi
118.642.672 zote i zosta w caoci wpacony.
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