In light of the fact that many web sites (such as USENIX) have not
 updated Prof. Gutmann's paper to include his Epilogue; especially the
 sites promoting a 35-pass program FOR SALE, I decided to include his
 comments here.
    This is a verbatim copy from the end of his paper (which can be
 found at:
    http://www.cs.auckland.ac.nz/~pgut001/pubs/secure_del.html ).

==========================================================================
 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). 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.

 Peter Gutmann. (Some time after July, 1996 and before February 2002; no
                 date is given in the paper for this Epilogue.)

===========================================================================


EOF.