[unisog] Wiping hard drives before computer transfer

Martin Radford Martin.Radford at bristol.ac.uk
Fri Jan 24 16:55:10 GMT 2003

--On 23 January 2003 16:14 -0600 Marty Hoag <Marty.Hoag at ndsu.nodak.edu>

>     I'm curious what others are doing to remove data and
> software from hard drives of surplused or "passed down"
> PCs and Macs.  Besides things like FERPA and licensed
> software concerns, there could be some liability if we
> passed along a machine which had already be compromised
> and potential embarrassment of revealing old data.

We use a tool I wrote which simply writes ASCII NULs across the disk,
together with a counter at the end of each megabyte.  It then goes back
and checks that the disk looks as it expected.

The write up is at

I don't claim that this would be enough to thwart a determined
attacker, but it's enough to stop the embarassment of a system finding
its way onto the second hand market with confidential data that just
needs to be undeleted using a DOS tool.

It wouldn't be difficult to extend the tool to do multiple passes and
write random data if that was required.

Martin Radford  (Martin.Radford at bristol.ac.uk)
Personal Computer Systems Team
Information Systems & Computing
University of Bristol Information Services
PGP keyID:       5D2D92E9
PGP fingerprint: 137E 0277 9D78 7447 71D0 BB3D C20D BB9A 5D2D 92E9

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