If you are concerned enough about the content of a hard drive to be giving
consideration to over-writing the content nine times then you should
probably give consideration to destroying the hard drive rather than just
over writing it's contents. The normal way of doing this is by opening the
hard drive and and giving it a good going over with a blow torch or
something similar. This oxidizes the magnetic surface of the disks making it
permenantly useless.
Appreciable over writing a disk three times is normally conisidered adequate
and most government agencies would be happy with nine. But all these
recommendation come with the caveat that if the disk heads have moved at
some point during the life of the disk you may be overwriting a different
section of disk to that which held the sensitive data.
The main scenario where data would be considered sufficiently sensitive for
this type of drastic measure would normally be disk drives on which high
value cryptographic keys have been kept, e.g. perhaps used for high value
banking transactions. Although of course any scenario where commercially
valuable data has been stored may be worth considering.
At the end of the day which is more important donating free hard drives to
staff or protecting company secrets.
Regards,
David Pybus
Security Engineer - COLT Internet
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This archive was generated by hypermail 2b30 : Fri Jun 22 2001 - 15:04:37 PDT