On Wed, 09 Mar 2011 15:30:30 -0600
cctalk-request at
classiccmp.org wrote:
Message: 22
Date: Wed, 09 Mar 2011 12:46:24 -0800
From: Eric Smith <eric at brouhaha.com>
Subject: Re: Who will be the last HD maker down the road?
To: General Discussion: On-Topic and Off-Topic Posts
<cctalk at classiccmp.org>
Message-ID: <4D77E720.3050100 at brouhaha.com>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
Richard wrote:
Flash memory is problematic for secure data.
Basically, its nearly
impossible to securely erase a file from flash based disks.
vintagecoder at
aol.com wrote:
I don't know how that can be true. I can
understand deleting doesn't
work but is it true a simple dd if=/dev/zero of=/dev/sdx onto the
flash card doesn't fill it with zeros?
That's *exactly* the problem. It doesn't. dd only fills the blocks
that are currently in use, but the card may have spared out marginal
blocks that still contain residual user data.
Then I would think a few passes of filling it with random data should work.
This is true of modern hard drives as well.
I like flash because you can snap them in pieces easily ;) All the theory
comes to an end at my pair of vice grips!
That's why the "secure erase" commands were added to the ATA command
set, and the drive is supposed to erase even the spared blocks.
I don't trust that to work. But I do trust my vice grips.