On 17 Nov 2002, at 13:20, Dave Schroeder wrote:

> What do they mean by "government wipe" in this thread?
> Dave

  When you delete a file "normally", the name is removed from the folder
directory and the data blocks are added to the pool of "available" blocks.
The data that was in the file is still sitting in those blocks.

  A few utilities out there include a routine for writing over ("wiping
out") all blocks in the "available" pool, to remove traces of old file
information.  These generally offer two modes:

1.  Simple
  Write zeroes (binary, not the digit "0") everywhere.  Software that
attempts to read unallocated disk space will just come up with these zeroes.
 This is "good enough" for most purposes.

2.  "Government Wipe"
  Forensic labs may have equipment (special hardware) to analyse the details
of magnetic traces on the drive platter surface.  Although the most recent
bit written was a zero, such equipment may be able to tell if it was
replacing a 0 or a 1.
  On this setting, the wiping software writes each block of the drive
multiple times, with different random garbage -- allegedly, enough that
these forensic devices can no longer recreate the former drive contents.

  [The name comes from a notion that this degree of erasure should be
applied to all drives used in government machines before they are disposed
of, in case any of the data was classified or sensitive.  I am told that
some agencies actually break up drive hardware for disposal, and do not
really rely on a software utility like this....]

David Gillett

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