http://www.madisonlinux.org/pipermail/m ... 07261.html
On Wed, Oct 29, 2003 at 08:24:46AM -0800, Darrick Hartman wrote:
> Thank you to everyone who replied...including the
> numerous people who obviously love this dban project.
> My hard drive does not function properly. It has bad
> sectors which prevent me from writing to it. It is
If the drive still powers up you can probably run a
low level formatter on it and get access to 99% of the
sectors. Once you have a cleaner format you can run
your DBAN or whatever on it and be sure that the sectors
that weren't corrupted are now wiped fairly clean.
Which formatter you'll use depends on the manufacturer.
IBM/Hitachi would use IBM's Drive Fitness Test program, ex.
> covered by warranty. Unfortunately, I cannot affect
> the data on the disk with any other method than a
> magnet and still send it back for warranty
> replacement. (I thought I could, but the drive is
> "more deader" than I thought.
Give the low level format a try before you give up.
> While it is intriguing, I don't think that the
> reseller would appreciate my sanding skills on the
> plattens. If I really really just wanted to kill the
> drive, I would put it through one of our high
> temperature furnaces (oh 2500F should do it) or
> chemically dissolve it in some nasty acid. That's not
> the case.
You could always ask them if it's permissable to trash the
drive, as you have your banking records on it. Can't hurt....
Indeed, very little on disk drives is proof against someone who
dismantles it and runs a scanning electron microscope over it to
analyze the remnant magnetism. One pass with zero's will defend you
against casual snoopers. A few passes of varying data will defend you
against anyone with a smaller budget than the NSA.
Note that the sufficiently well funded can play analagous games with
semiconductor memory; if you store data in RAM for a long time there
are ways of analyzing the chips to deduce a lot of it too. Paranoid yet?
Degaussing magnets are pretty much a lost cause, sorry. The
coercivity of modern disk and tape media is so high that pretty much
no one outside a fusion research lab has magnets (usually
superconducting) strong enough to do the job.
To keep people from reading your data, you need either encryption,
multiple erasure passes, or thorough physical destruction.
Have been for a while
Note, too, that getting the RAM very cold (e.g., a liquid nitrogen bath)
quickly after shutdown should allow it to keep its state for quite
some time after the power button goes off(certainly long enough to get it
to the lab).
Also, this is a good point for people who use encrypted file systems.
Likely, the key will be stored in memory, probably in the same location,
for quite some time. It'd be nice if the crypto kernel drivers would hook
into the VM code and change the physical memory address in the relevent
memory pages on a regular basis (not sure if it does already).
So, what would it take to protect the contents of your RAM from everyone
but the NSA? Sounds like this might be as much of a challenge.
Just a thought...
no security measure is worth anything if an attacker has physical access to the machine