[SOLVED] securely wiping files on a FAT32 disk

Wim Sturkenboom · 08-22-2012, 08:58 AM

I have this old Win98 system that was donated to an organization and still contains data of the original owner (divorce, bank statements etc). I like to (more or less) securely wipe files (most probably in my documents or so).

I can basically make no mistakes (no original install media, only an untested image) so I like some confirmation if the approach as described in http://en.gentoo-wiki.com/wiki/Secure_deletion will work for a mounted FAT32 disk.

Quote:

delete the files (in W98 or using live usb)
fill the free space with a massive file with zeros and delete that file

Code:

dd if=/dev/zero of=zerofile bs=1M
sync
rm zerofile

m1chel · 08-22-2012, 09:06 AM

I think: not completely. First, there is a 4 Gb size limit on a single file in FAT32. So if your drive is larger, not all the free space will be erased. Second, you cannot erase data that's in a partially used cluster that way. I think there's a package called scrub to do what you want, only I have never used that.

Hope this helps (a bit).

H_TeXMeX_H · 08-22-2012, 09:07 AM

m1chel is right, there is the size limit which will not allow this method to work.

If you want some extra security you can wipe with random numbers, use wipe:
http://wipe.sourceforge.net/
it is much faster than using /dev/urandom and is designed for this. Wipe the entire device with it.

Or you can download the UBCD (link in my sig), boot it and use the various wipe utilites there, I recommend DBAN.

TobiSGD · 08-22-2012, 09:08 AM

That will work.
If you want to be paranoid you can also use the same approach but /dev/urandom instead of /dev/zero after you have zeroed the free space out the first time.

Edit: Forgot about the 4GB limit, maybe you need more than one file. AFAIK, there are no partially used clusters on FAT file-systems.

Wim Sturkenboom · 08-22-2012, 10:18 AM

Thanks

specially for the warning; it might not even be FAT32 (need to check what it is and what the specs are

)

Total HD is 4.3GB

minus Win98 and Office97 should bring me well within the 4GB limit.

// Edit:
I can't wipe the HD as there are no installation media of either Win98 or Office97. Machine is going to be used to teach people a bit of computer skills and office SW skills.

H_TeXMeX_H · 08-22-2012, 01:17 PM

I see, well then in this special case it probably would work.

273 · 08-22-2012, 01:23 PM

Under Linux you can use "shred" to write over and delete individual files though, of course, this won't get files which have already been deleted as the filling with a random file method would.

Wim Sturkenboom · 08-22-2012, 02:51 PM

Currently wiping. First attempt with /dev/urandom and after 1.5 hours the 'filesize limit exceeded' message showed; file was 2GB.

Now using /dev/zero for the next one; seems to go a bit faster

Available space after removing files is 3.3GB that needs to be wiped.

//Edit
marked as solved but need to wait till this one is finished to see if I did not bork Win98

Wim Sturkenboom · 08-22-2012, 03:08 PM

Thanks people,

Win98 and Office97 have survived :lol: