Messages in this thread |  | | From | Andreas Dilger <> | Date | Fri, 17 Aug 2001 14:08:31 -0600 | Subject | Re: ext2 not NULLing deleted files? |
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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
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