Shredder ?!

[Mario Vukelic]

On Fri, 2006-12-08 at 10:36 +0700, Chanchao wrote:
> secure shredding program/applet 

I forgot to add in my other reply: note that man shred says that is not
secure on journaled file systems, raid-based file systems, NFS 3, and
compressed file systems. So it is actually pretty useless.

Here is some info: http://en.wikipedia.org/wiki/File_wiping
>From this it seems that wiping files on ntfs is also not secure, but I
am no Windows expert

IIRC wipe is more useful, but, again IIRC, is usually used on unmounted
partitions.

You have to ask the question what you want to guard against: keep in
mind that that there is no simple "undelete" to recover deleted files.
See the ext3 FAQ [1]

"Q: How can I recover (undelete) deleted files from my ext3 partition?
Actually, you can't! This is what one of the developers, Andreas Dilger,
said about it:

In order to ensure that ext3 can safely resume an unlink after a crash,
it actually zeros out the block pointers in the inode, whereas
ext2 just marks these blocks as unused in the block bitmaps and marks
the inode as "deleted" and leaves the block pointers alone.

Your only hope is to "grep" for parts of your files that have been
deleted and hope for the best."

On reiserfs there seem to be ways, but it isn't easy: [2]
xfs seems pretty impossible: [3]

If you have high security requirements for discarded disks you shouldnot
rely on wipe, but physically destroy the disk. [4]


[1] http://batleth.sapienti-sat.org/projects/FAQs/ext3-faq.html
[2]
http://antrix.net/journal/techtalk/reiserfs_data_recovery_howto.comments
[3] http://oss.sgi.com/projects/xfs/faq.html#undelete

[4] Professional, e.g.: http://www.semshred.com/content291.html 
DIY: http://driveslag.eecue.com/