Re: ext2 not NULLing deleted files?

[Andreas Dilger <adilger@turbolabs.com>]

On Aug 17, 2001  12:55 -0500, Mark H. Wood wrote:
> Regarding the need to do more than just zero unwanted data, I note that
> there is a U.S. DOD MIL-SPEC (no, I do not know the number) which defines
> a sequence of patterns to be used for erasing magnetic media.

In the Usenix paper quoted earlier in this thread (I believe) it was
stated that the MIL-SPEC document was actually bogus.  REAL secure
deletion requirements were much more strict (something like 15 passes of
various random and non-random patterns vs. 7 passes of alternating all 0
and all 1 data), but the US government made it think that the MIL-SPEC
requirements were enough, so that naive users would follow it, still
leaving enough trace data on the disk for the government to retrieve it.

Still, even a single pass of zero writes is enough to prevent 99.9%
of attackers from getting the data back.

Cheers, Andreas
-- 
Andreas Dilger  \ "If a man ate a pound of pasta and a pound of antipasto,
                 \  would they cancel out, leaving him still hungry?"
http://www-mddsp.enel.ucalgary.ca/People/adilger/               -- Dogbert