speeding up hard drive wipe

[Ralf Mardorf]

On Sat, 26 Sep 2020 15:07:01 -0400, Ken D'Ambrosio wrote:
>Citation, please.

There might be no proof, but it's reasonable and not just another
idiotic conspiracy theory.

Users unlikely need to worry about this:

  "A technique called  Magnetic  Force  Microscopy  (MFM)  allows  any
  moderately  funded  opponent  to  recover  the last two or three
  layers of data written to disk"¹

HDDs aren't 42 MiB small anymore, so the technology changed for HDDs,
let alone SSDs, making it quite questionable, if recovery of "layers" is
possible at all. It was possible, but might be impossible today. Even if
recovery should be possible, recovering data on drives with TiBs of
storage space via microscopy or other techniques seems to me irrational.

Not irrational is this guess:

  "Be aware that harddisks are quite intelligent beasts those days.
  They transparently remap defective  blocks.  This means that the disk
  can keep an albeit corrupted (maybe slightly) but inaccessible and
  unerasable copy of some of your data.  Modern disks are said to  have
  about  100%  transparent remapping capacity.  You can have a look at
  recent discussions on Slashdot.

  I hereby speculate that harddisks can use the spare remapping
  area to secretly make copies of  your  data.   Rising
  totalitarianism  makes  this  almost  a  certitude.  It is quite
  straightforward to implement some simple filtering schemes  that
  would  copy  potentially interesting  data.   Better,  a
  harddisk  can  probably detect that a given file is being wiped,
  and silently make a copy of it, while wiping the original as
  instructed.

  Recovering such data is probably easily done with secret
  IDE/SCSI commands.  My  guess  is that  there  are agreements
  between harddisk manufacturers and government agencies."¹

However, if so, then wiping gains absolutely nothing at all. IMHO
overwriting data just one time is enough. It's already not easy to
recover deleted, IOW _not wiped data_, when right after deleting the
drive is remounted read only. In my experiences it's impossible to
recover 100% and while it might be possible to recover 95%, you don't
get back directory structures and you need to sort and (re)name the
recovered data manually. The run-of-the-mill recover approach worked
very well for 5 1/4" Commodore 1541 floppy disks, but it's a pain with
GiB and TiB HDDs. I never tested it with SSDs.

¹http://manpages.ubuntu.com/manpages/trusty/man1/wipe.1.html