full-disclosure - Erasing a hard disk easily

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From: listuser at seifried.org (Kurt Seifried)
Subject: Erasing a hard disk easily

This is off topic.

As well the subject line and what most of you are discussing is not
"erasing" a hard disk, but rather overwriting the data. No amount of
overwriting data will "erase" a disk. To "erase" a disk you need to apply a
relatively high magnetic field (like say one... generated by a disk eraser
perhaps) and reallign all the magnetic particles on the disk to ensure the
data is gone. Simply overwriting the data will not overwrite all magnetic
particles. Off track particles, particles in lost sectors/bad clusters,
particles in the host protected area (read the ATA spec folks), etc, etc.

Again I repeat: no amount of overwriting data on a hard drive will ensure
that it is gone. To add to this is the fact that most disk wpiing programs
are broken and don't fully wipe the disk (read various vendor reports/etc,
sure they're biased but they do contain some truth).

Personally I pull the drives, bash them to s**t with a crowbar, wrap them up
with some smelly garbage and toss them in a dumpster usually the day before
it gets emptied by the trash company. New hard drives are cheap, and giving
someone old drives isn't exactly that nice IMHO ("here's something to store
your data, it might work for a while, heck if I care").

Now can we please drop this incredibly lame thread.

Kurt Seifried, kurt@...fried.org
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http://seifried.org/security/