data shredder

Gilles Gravier ggravier at fsfe.org
Mon Dec 21 08:08:58 UTC 2009


If you want to be sure your data gets shredded, use an encrypted
filesystem either through LOFI, or using Solaris' ZFS file system, or
some other full disk encryption tool.

On my Ubuntu Netbook, I use TrueCrypt : http://www.truecrypt.org/ which
is nice because it encrypts to a FAT filesystem... and the resulting
encrypted volumes can be shared with Windows or MacOS.

Deleting a file from an encrypted volume results in random data being
put there.

You can also look at projects like assured delete from my colleague
Radia Perlman : http://research.sun.com/techrep/2005/abstract-140.html

Gilles.

On 21/12/2009 08:26, Emil Payne wrote:
>
> NoOp wrote:
>   
>> On 12/20/2009 07:28 PM, jesse stephen wrote:
>>     
>>> I'm looking for a data shredder for ubuntu 9.10
>>>
>>>
>>>       
>> $ man shred
>>
>>
>>
>>
>>     
> From MAN SHRED - Note the info about EXT3:
>
> CAUTION: Note that shred relies on a very  important  assumption:  that
> the file system overwrites data in place.  This is the traditional way
>     to do things, but many modern file system designs do not  satisfy
> this       assumption.   The following are examples of file systems on
> which shred       is not effective, or is not guaranteed to be effective
> in all file sys‐       tem modes:
>
>        * log-structured or journaled file systems, such as those
> supplied with AIX and Solaris (and JFS, ReiserFS, XFS, Ext3, etc.)
>
>        * file systems that write redundant data and  carry  on  even  if
>  some writes fail, such as RAID-based file systems
>
>        *  file  systems  that  make snapshots, such as Network
> Appliance's NFS server
>
>        * file systems that cache in temporary locations, such as NFS
> version 3 clients
>
>        * compressed file systems
>
>        In  the  case  of  ext3 file systems, the above disclaimer
> applies (and shred is thus of limited  effectiveness)  only  in
> data=journal  mode, which  journals  file  data  in addition to just
> metadata.  In both the data=ordered (default) and data=writeback modes,
> shred works as  usual.
>
>        Ext3  journaling  modes  can  be  changed  by adding the
> data=something option to the mount  options  for  a  particular  file
> system  in  the /etc/fstab file, as documented in the mount man page
> (man mount).
>
>        In  addition, file system backups and remote mirrors may contain
> copies of the file that cannot be removed, and that will allow a
> shredded file to be recovered later.
>
>
>   




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