Re: *nix data wipe tools

From: Wietse Venema (wietse_at_porcupine.org)
Date: 12/17/04

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    To: bugtraq@securityfocus.com
Date: Fri, 17 Dec 2004 13:05:37 -0500 (EST)

    David Cannings:
    > Thomas C. Greene wrote:
    > > I've posted the final versions of a few simple, free shell scripts that i've
    > > been working on to make data hygiene more convenient on *nix systems. Thanks
    > > to list members who helped test them and contributed improvements.
    >
    > Is there any specific advantage of these scripts over bcwipe?
    >
    > http://www.jetico.com/index.htm#/bcwipe_unix.htm

    There's a general problem with applications that go through the
    file system to destroy the contents of a file. Unless one uses
    very simplistic disk harware and file systems, there is no guarantee
    that overwrite requests will actually overwrite the intended bits.
    For a example, Solaris 10 ZFS uses copy-on-write, to avoid corruption
    when the system crashes in the middle of an update; many disk drives
    have write caches built-in so only the last overwrite request takes
    effect; and non-volatile memory "disks" have a limited number of
    write cycles and try to avoid hot spots.

            Wietse

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