Mailinglist Archive: opensuse (2459 mails)

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Re: [opensuse] scrathsing old harddisks
  • From: Sam Clemens <clemens.sam1@xxxxxxxxx>
  • Date: Wed, 26 Mar 2008 23:33:48 -0400
  • Message-id: <47EB159C.60604@xxxxxxxxx>
Greg Freemyer wrote:
On Wed, Mar 26, 2008 at 6:38 AM, Hans defaber <hans.defaber@xxxxxxxxx> wrote:
What is the best (easiest) way to overwrite old harddisks with random garbage ?

thanks, Hans

Lots of ways, but the easiest is "dd if=/dev/zero of=/dev/sdX bs=4k

Basically everything beyond that is overkill. Even NIST has started
buying off on the above for drive 20GB or larger. holding confidential
data (Older, less dense drives need more passes, random data, etc.)
For more secret data, they require physical destruction I think.. I
have not seen any docs that cover drives holding top secret data etc.

U.S. government SECRET requires a low-level format.
TOP SECRET requires destruction of the disk platters.

If you need a boot CD/floppy look into dban.

If you think you data is worth someone attempting a multi-million
dollar recovery on and you think their is an ultra-secret government
agency that actually has some SciFi like ability to recovery
overwritten data, then take it apart and belt sand the magnetic media
off of each platter.

You would be amazed at what can be accomplished with scanning
electron microscopes (due to the fact that the path of an
electron is effected by magnetic fields.). From what I
understand, due to hysteresis effects, a track starts out
at 'full width', but each time a magnetic field is reversed,
a "tail" is left on each side. Apparently, these residual
fields can be used to reconstruct data which was previously

> You should probably do that while wearing an
aluminum hat. That way they can't be reading your mind during the
process and somehow be using you as a transmitter to read your data.


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