1) Gutmann's 35 passes were devised to stress the recording methodologies
of the day. Many of them are for encoding schemes not used anymore.
2) Canadian RCMP TSSIT OPS-II says: "Must first be checked for correct
functioning
and then have all storage areas overwritten once with the binary digit ONE,
once with the binary digit ZERO and once with a single numeric, alphabetic or
special character, " (http://jya.com/rcmp2.htm)
American DoD 5220-22.M says: "Overwriting all addressable locations with a
character, its complement, then a random character and verify." This is
permitted for classifications up to SECRET. It is not acceptable for
TOP SECRET and higher.
I have to conclude that *our* spooks are of the opinion that even 3 passes
are sufficient to wipe out data thoroughly enough so that it's not worth it
for the *other* spooks to try recovering 'Secret'...