Subject: securely erasing a hard disk
To: NetBSD Tech Security <>
From: Philip Jensen <>
List: tech-security
Date: 10/21/2005 13:35:24
I am wanting to understand the risk outlined in this paper:-

Is it widely acknowledged that a disk (or file) needs to be
overwritten up to 30 times in order to remove any traceable
information on the magnetic media for the file?

If so, then does the -P switch for the NetBSD rm command really
provide the "security" of data erasure people think they are getting?=20
Or should the man page have an addition of "If you are serious about
removing all traces of this file then ......."?

Lastly, how long would it take to retrieve the contents of a disk (or
file) which has been overwritten with `dd if=3D/dev/zero of=3D/dev/rsd0c`?