Re: [Full-Disclosure] erase with magnet

From: Michael Cecil (
Date: 04/03/04

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    Date: Sat, 03 Apr 2004 11:09:34 -0600

    At 12:22 PM 4/3/2004, Alexander Heidenreich said:
    >Am Samstag, 3. April 2004 15:36 schrieb B$H:
    >> I'm interested in the original question about erasing a harddrive using a
    >> magnet. Is it possible to erase data on a hard disk drive with a powerful
    >> magnet, but then be able to use the drive and the PC again?
    >That depends. Some harddrives are having a part of the bios in a protected
    >sector. If you delete it, the drive isn't usable any more. The next question
    >is the strength of the magnet. You need the same or stronger magnetic field
    >to write to the surface than the magnetic field you've used to delete.
    >After all it's theoretical possible to read some fluctuations of the
    >field to restore your deleted data. It's better to overwrite the harddisk
    >several times with random data to be shure everything is really deleted.

    If the magnet is strong enough to degauss the platters, it is strong enough
    to totally screw up the alignment of the heads.

    If you want to sanitize a drive and then reuse it, use a overwriting tool
    such as Autoclave <> or
    Eraser <> and use the overwriting setting
    recommended by Gutmann

    If you want to sanitize the drive and discard it, then grind it up into
    little crumbs and burn the crumbs. I just autoclave mine and then
    disassemble the platters to use as wind chimes.

    Michael Cecil
    Full-Disclosure - We believe in it.

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