On Wed, Jul 25, 2012 at 17:38, Paul de Weerd wrote: > Please read > > http://www.vidarholen.net/~vidar/overwriting_hard_drive_data.pdf > > I think it's time to stop propagating the Guttman lies. Overwriting > more than once does not help.
In fairness to Guttman, he's not the liar. The paper, linked below, is still an interesting read. But as he notes in the epilogue, "In the time since this paper was published, some people have treated the 35-pass overwrite technique described in it more as a kind of voodoo incantation to banish evil spirits than the result of a technical analysis of drive encoding techniques. As a result, they advocate applying the voodoo to PRML and EPRML drives even though it will have no more effect than a simple scrubbing with random data. In fact performing the full 35-pass overwrite is pointless for any drive since it targets a blend of scenarios involving all types of (normally-used) encoding technology, which covers everything back to 30+-year-old MFM methods (if you don't understand that statement, re-read the paper)." http://www.cs.auckland.ac.nz/~pgut001/pubs/secure_del.html [I think naddy's suggestion to use arc4random is reasonable will update for that soon.]