Messages in this thread | | | Subject | Re: secure erasure of files? | Date | Tue, 19 Feb 2002 19:48:58 +0100 (MET) | From | (Rogier Wolff) |
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Martin J. Bligh wrote: > > Some success is rumored to be able to be achieved by sampling the > > normal signal, and then subtracting the "expected signal assuming the > > current sequence of bits that was read". That way you might be able to > > recover the information that peeks out from below. > > It's more than rumour - I've seen this done. Dr Solomon's (whatever > they called their data recovery branch), early 1990's, England. > Maybe it was easier on older hardware like the MFM / RLL disks, > and certainly easier to piece together fragmented data with earlier > file formats.
Maybe the difference is in "what's the goal". For datarecovery we don't really care about just a couple of bits here and there: We want to piece together the whole thing.
If you don't want a piece of your data getting into wrong hands however, you'd better be safe than sorry.
So I (and the Ibas guy) are talking about practical recovery of a useful amount of data, while even a couple of bits is in theory dangerous if you really want it "gone".
> I believe the point of overwriting 3 times (or whatever) is to reduce > the "subtracted difference" to noise levels where it's no longer useful.
Right.
Roger.
-- ** R.E.Wolff@BitWizard.nl ** http://www.BitWizard.nl/ ** +31-15-2137555 ** *-- BitWizard writes Linux device drivers for any device you may have! --* * There are old pilots, and there are bold pilots. * There are also old, bald pilots. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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