Peter Gutmann's Epilogue some time after 1996 and before 2002
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). If you're using
a drive which uses encoding technology X, you only need to perform the
passes specific to X, and you never need to perform all 35 passes. For
any modern PRML/EPRML drive, a few passes of random scrubbing is the best
you can do. As the paper says, "A good scrubbing with random data will do
about as well as can be expected". This was true in 1996, and is still
true now.
Dose anyone understand all of this. I am missing bits. Some of it is over my head.