Bruno Wolff wrote:
Given 1, this seems like a foolish policy. Just eat the cost as part
securing your data. It might be cheaper than having you keep an eye of
multiple write passes covering several days.
"I have no comment at this time." :-)
There was some old documentation that claimed reading the remmants
previous writes were recoverable, though I don't remember seeing costs
estimates that low. I would have expected a lot of human time needed to
help deal with the incomplete recovery.
I suppose the cost of such equipment is much cheaper now than in the
olden days of 15 years ago. Also, given my comment below, a sensitive
read head (rather than an MF or AF Microscope) may be all that's
needed in the case of a "zero write-over".
If one can recover a significant amount of data after writing zeros,
is going to be able to do it after writing a single pass of random data
I don't think this is correct, based on my reading. The situation is
a little bit like trying to decrypt a file after adding an unknown
constant numerical value to the data, vs. adding a "one-time pad" of
random numbers. That's because writing zeros does not completely zero
out the local magnetic orientations so the variations can still be
detected. A random pattern makes the problem much harder. Multilple
passes (which is what /usr/bin/shred does) makes it even harder.