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  1. #1
    iNET Interactive
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    PERIMETER SCAN

    Wiped hard drives pose little data-theft risk


    By Ryan Russell

    You're probably aware that when you delete a file — even from the recycle bin — it's not really gone; Windows has, in effect, deleted the file's address on the hard drive.



    You likely also know that completely erasing a file requires thoroughly writing over its bits on the hard drive, though not as thoroughly as you might think.

    The full text of this column is posted at WindowsSecrets.com/2010/10/21/07 (paid content, opens in a new window/tab).

    Columnists typically cannot reply to comments here, but do incorporate the best tips into future columns.
    Last edited by revia; 2011-01-19 at 14:48.

  2. #2
    New Lounger
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    I work for a company that makes RAID adapters. We have been using SSD drives extensively. All SSD drives that we use have a feature called Secure Erase. I'm told that this feature was requested by government agencies because of the same issues you mention in your article.

    It is a 3 step process that erases the entire drive.
    1. Set security password
    2. Secure erase device
    3. Disable password

    We have made our own tool that sends the 3 SATA commands required. I've heard that HDDerase.exe will also work.

  3. #3
    New Lounger
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    You wrote that "...your only choice for flash devices should be physical destruction."

    I wonder if something like FillDisk from CyLog Software (http://www.cylog.org/utilities/filldisk.jsp) would work, after deleting all files on the flash drive?

    From the CyLog site: "FillDisk is a simple utility that fills up a disk with data. It starts with 1GB files, then drops to 512MB, 256MB and so on until it fills up completely the disk with files."

    These new files - containing nothing but zeros - can then be deleted. Should work, shouldn't it?

  4. #4
    Lounger
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    Do the individual memory cells in a flash memory or SSD actually retain anything once the state of the cell is changed? That is, rotating disks retain a magnetic imprint of a previous state, but flash drives and SSDs are just transistors in complex arrangements. Once a cell is changed from 1 to a 0, does it retain any evidence of the previous 1? It would seem that flash memory and SSDs should only contain what data is currently stored, plus whatever is in the extra cells that allow wear leveling. If that's so, erasing is pointless, and if you want to get rid of the drive for some reason you could probably just fill it with Jabberwocky or transcripts of political speeches.

  5. #5
    New Lounger
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    Quote Originally Posted by Kim Boriskin View Post
    ... If that's so, erasing is pointless, and if you want to get rid of the drive for some reason you could probably just fill it with Jabberwocky or transcripts of political speeches.
    That's what FillDisk does -- fill up the available space on a drive with files containing zeros. (So all existing files would need to be deleted first.)

    I suppose the real question is the one in your first sentence.

    Perhaps someone with more technical know-how on flash drives can provide more information. I hope so, since I have several flash drives that might be donated -- but only if there are no residual traces of any data, after everything has been erased and they have been treated with FillDisk.

  6. #6
    New Lounger
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    Quote Originally Posted by Noah Misner View Post
    All SSD drives that we use have a feature called Secure Erase.
    Ah, interesting, thanks. Do you know if this is standardized, or if the command is proprietary per manufacturer?

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