[NBLUG/talk] OT: Bulk erasure

[Andru Luvisi]

If I recall correctly (and I may not) the standard approach is to
overwrite the data once, then again with the compliment of the first
pattern, and then with random data.  Frequently, one pass with all zeros,
one with all ones, and then one with random data.  Repeat this three pass
operation a number of times proportional to your level of paranoia.  When
working with tapes, be sure to use the device that rewinds when you close
it.  This process will take a very long time.

# DEV=/dev/st0  # SCSI tape 0
# DEV=/dev/hda  # First IDE disk
i=0
while [ $i -lt 5 ]
do
  dd if=/dev/zero of=$DEV
  perl -e 'for(;;) { print "\xff"; }' |dd of=$DEV
  dd if=/dev/urandom of=$DEV
  i=`expr $i + 1`
end

I know that they make BULK ERASERS that are powerful enough to make disks
and tapes unreadable without special equipment, but such BULK ERASERS are
expensive.  The cheap BULK ERASERS that you can get for erasing floppies
will probably not be of much use against a hard disk or a magnetic tape.
Of course, even using a powerful BULK ERASER, or the multi-pass approach
given above, some information might be recoverable with an electron
microscope.  The only completely safe way to erase the media that I know
of is to let the disk or tape disolve in acid.

Andru
P.S. We could fix that with a... BULK ERASER!!!

P.P.S. BULK ERASER!!!
-- 
Andru Luvisi, Programmer/Analyst


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