Wiping Out Data

[Jeffrey F. Bloss]

Matthew Flaschen wrote:

> Jeffrey F. Bloss wrote:
> > It should also be noted that utilities like shred and dd can be utterly
> > useless on file systems like ext3
> 
> That applies when you shred an ext3 /file/, but in this case I told him
> to shred the whole block device directly.  That will simply overwrite
> all blocks, at a lower-level then the filesystem.  The drive isn't even

I don't believe this is correct because dd doesn't work at that
level. The command you suggested... 'dd if=/dev/random of=/dev/sdb'
*should* fail with a "no media" error unless sdb is mounted. Actually
it should fail either way because you're not pointing dd at an
accessible target partition. But there may be file system specific
factors that make YMMV applicable. ;)

> mounted, so there can't be journaling.  Afterwards, the filesystem is
> destroyed (understanding it can still be probably be recovered by
> sensitive forensics), so it is necessary to run mkfs .

I'm not sure mkfs does anything significant as far as "bit wiping" goes
either, although I'm not up on the mechanics of how it creates file
systems. It doesn't make much sense to write arbitrary data just to lay
out a partition though.

> 
> However, almost all USB drives are VFAT by default anyway so this isn't
> likely even an issue.
> 
> Matthew Flaschen
> 

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