Securely delete files...

[Jean-David Beyer]

-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1

David Shaw wrote (in part):

> That's exactly the problem - given modern disks, and modern  
> filesystems, there is not a perfect guarantee that you'll hit the same  
> disk blocks that the original file landed on.  The disk could  
> invisibly remap a block out from under you at any time (it does this  
> automatically when the disk firmware detects a bad block), the  
> filesystem could be doing journaling games, etc, etc.  A program  
> running on the computer the disk is attached to can't really do much  
> about disk block remapping since it doesn't see this.  It always asks  
> for (for example) block 100.  If the file was written when block 100  
> pointed to block 100, but by the time the overwrite happens, block 100  
> has become 12345, then the computer doesn't know it needs to overwrite  
> both 100 and 12345 to get all traces of the file.
> 
To make matters worse, block 100 in your example may have already been
allocated to another process and it may have already written by that other
process, so the computer better not overwrite it multiple times to hide all
traces of the older data.

- --
  .~.  Jean-David Beyer          Registered Linux User 85642.
  /V\  PGP-Key: 9A2FC99A         Registered Machine   241939.
 /( )\ Shrewsbury, New Jersey    http://counter.li.org
 ^^-^^ 07:40:01 up 15 days, 13:46, 4 users, load average: 4.54, 4.28, 4.37
-----BEGIN PGP SIGNATURE-----
Version: GnuPG v1.4.5 (GNU/Linux)
Comment: Using GnuPG with CentOS - http://enigmail.mozdev.org

iD8DBQFIrqgCPtu2XpovyZoRAjfdAJ4l5Lx5kNZikfe1p+jk1OF8v4UTwACg08rI
7XUxC1ICpb/yJVQe9b8i4kE=
=bM+I
-----END PGP SIGNATURE-----