Wiping Out Data

[Jeffrey F. Bloss]

Carsten Aulbert wrote:

<snip> 

Just for grins I tried duplicating your commands precisely, "forcing" dd
to write bytes.

I got the same subsequent sfdisk and mount errors you got, but when I
removed and remounted the device every bit of the original file system
and data were right there and in tact. As if by magic. ;)

So no, dd obviously does *not* work at this level and "write directly
to hardware" as has been suggested in essence, even when you force an
illusion of it doing so. Multiple dd overwrites are likely to fail
because of this, making dd "more or less useless" for the secure wiping
of a USB device unless additional steps are taken (interspersed sync
calls?), as I originally asserted.

I'd wager that dd fails in this context too, even if as Matt suggested
you immediately recreate a file system on the "overwritten" device.
Existing data would be obfuscated, but only as it would be if you truly
accomplished a single successful pass of dd.

-- 
     _?_      Outside of a dog, a book is a man's best friend.
    (o o)         Inside of a dog, it's too dark to read.
-oOO-(_)--OOo------------------------------[ Groucho Marx ]---
                    http://wrench.homelinux.net/~jeff/
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