Re: simple way to securely destroy deleted files in a file system

["H.S." <hs.samix@gmail.com>]

On 15/07/10 01:38 PM, Perry E. Metzger wrote:
> On Thu, 15 Jul 2010 12:05:33 -0400 "H.S." <hs.samix@gmail.com> wrote:

>> Its first and second partitions (sdc1 and sdc2) are vfat. I was
>> thinking of mounting these on /mnt/scd1 (and scd2) and then doing:
>> # dd if=/dev/zero > /mnt/sdc1/zeros.bin; rm -f /mnt/sdc1/zeros.bin
>>
>> and the same for scd2. The idea is fill the partition with new data
>> thus overwriting any deleted files' data that is lying around.
>> Would that be adequate? The objective is just to prevent a casual
>> recovery, reading and copying of the data by a future user, so I
>> don't need multiple over-writes.
> 
> I suggest dd'ing /dev/zero over the raw disk partition instead. That
> will zero out every single block of the file system. You can probably
> just do
> 
> dd if=/dev/zero of=/dev/scd bs=1M

Yes, but that would wipe out everything, the OS as well.

I was looking for just making the already deleted files unrecoverable by
a casual user. In other words, since a deleted file frees the space on
disk, by filling up the disk with all zeros and then deleting that zeros
file would be overwriting the earlier deleted files with zero. Am I
correct in this?





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