Re: Default number of overwrites in shred

[Jim Meyering]

Pádraig Brady <address@hidden> wrote:
> Jim Meyering wrote:
>> Paul Eggert <address@hidden> wrote:
>>> Jim Meyering <address@hidden> writes:
>>>
>>>> I too would feel better with a minimum of 2 or 3 passes, just in case.
>>> If we want to be conservative, then the U.S. Defense Security
>>> Service's Clearing and Sanitization Matrix (2005-06-27)
>>> <http://www.dss.mil/isp/odaa/documents/clearing_and_sanitization_matrix.pdf>
>>> specifies the following methods for rigid disk:
>>>
>>> * For clearing, "Overwrite all addressable locations with a single 
>>> character."
>>>
>>> * For sanitization, "Overwrite all addressable locations with a
>>>   character, then its complement.  Verify 'complement' character was
>>>   written successfully to all addressable locations, then overwrite
...
> I noticed a couple of blog posts lately that reminded me of this.
>
> http://www.g-loaded.eu/2009/01/22/effective-data-wiping-with-a-single-complete-overwrite/
> http://www.ioncannon.net/system-administration/272/using-scrub-to-destroy-a-hard-drive/
>
> Should be just change DEFAULT_PASSES to 3 now, and do the more complicated
> process above when someone gets time?

Sure.
Too many people waste too much time with the existing defaults.