Does formatting wipe the free space?

Discussion in 'Computer Science & Culture' started by wynn, Jul 27, 2010.

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  1. wynn ˙ Valued Senior Member

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    Elsewhere, a poster was talking about deleting files from her computer, and this was a reply to it:

    I didn't know what it means "to wipe the free space", so I googled it. It turns out a special program is needed for that.

    One bit of info I couldn't find:

    Does formatting the computer have the same effect, namely wiping the hard disk clean?


    Thank you.
     
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  3. baftan ******* Valued Senior Member

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    No it doesn't. Formatting doesn't wipe the hard disc.
     
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  5. river-wind Valued Senior Member

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    Quick formatting only wipes out the table that holds the structure of where are your files are located on the drive; it doesn't bother to wipe out the files themselves (this is also what happens when you delete a file with the trash - the link to where the file is on the drive goes away and the computer marks that drive space as available for re-use; it doesn't actually bother to remove the file data). As far as the computer is concerned, there is no space allocated to file data on that spot of the disk, and will treat all that space as if it's blank. Therefor it is good enough for most uses; the computer thinks it's empty, acts as if it's empty, and overwrites the old data with new data as needed.

    However, all your file data still exists in this now "unallocated" space. Until that space is used for storing new data, an undelete program can look for the file data manually and retrieve many of the files based only on their structure. Even without a link on the master file table (as when you delete a file from the trash), or if the file table is gone (as with the quick format).

    Think of it this way: you have a library and a card catalog. I burn only the card catalog. The books all still exist, but you have to search for everything manually now.

    A full/complete format will erase the whole drive, making all of the bits on the disk 0s and wiping out the files. Many OS's also include a secure or multi-overwrite, which makes the bits 0 then 1 then 0, either 3 or 7 times. This not only erases the data but also gets rid of any lingering hints of what the data might have been previously. Why this is worthwhile requires an explanation of how magnetic bits work, which I think is overkill here.

    To summarize: do a quick format if you want to use a disk for a new purpose, and don't care about the files on it. Do a complete reformat if you want to wipe out all the existing files. Do a complete format more than once if you want to sell the drive to another person, and don't want any chance that they could pull sensitive information like credit card numbers from that drive.
     
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  7. Stryder Keeper of "good" ideas. Valued Senior Member

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    It's called "Shredding", it's not as overkill as you might think if it's security related. As a well equipped forensic lab can actually map the bit alterations to recover data.
     
  8. Syzygys As a mother, I am telling you Valued Senior Member

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    He meant the explanation would be an overkill, not the data overwrite itself.

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  9. Dr Mabuse Percipient Thaumaturgist Registered Senior Member

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    No a format does not wipe the drive, even formatting the long way multiple times does not do it.

    But fear not internet citizens! There is a free program that everyone and their brother uses called CCleaner!

    It will securely wipe your free space 3 times, 7 times(which is NSA standard), or even a Gutmann(paranoid) wipe of 35 times. It makes doing this as simple as setting it up in Options>Settings>Secure Deletion(check 7 times). Then wipe free space and you're good. It will take a while.

    Also... millions and millions of people use this program because it makes cleaning out those excessive files that build up in Windows a breeze, and it will shred them every time so they are gone. It deletes browsing history and temp/cache files. It also has a useful registry cleaner.

    It's a program I recommend to most everyone.

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  10. wynn ˙ Valued Senior Member

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    CCleaner

    - I have it on my computer (it came with it), but "Wipe Free Space" is under "Advanced" options that I cannot run.

    What is wrong?
     
  11. Stryder Keeper of "good" ideas. Valued Senior Member

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    well some would believe the deletion to be a bit overkill, most of the time it's not really an issue unless you have something extremely important you don't want to fall into someone else's hands, things like "bank details", "Schematics for a nuclear device", "a list of sleeper agents" etc.

    Although saying that, most of those things are usually found online anyway.
     
  12. S.A.M. uniquely dreadful Valued Senior Member

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    How does Shift+Delete work? Does it delete the file on the disk or just its location? It bypasses the trash bin.
     
  13. Stryder Keeper of "good" ideas. Valued Senior Member

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    In pictorial terms, it just unticks a box as having relevant data in. You could with the right software actually "undelete" whatever was deleted, as long as of course it wasn't rewritten over. (If it was written over, then you need to get forensics on it.)
     
  14. S.A.M. uniquely dreadful Valued Senior Member

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    I use Shredder which "secure deletes" using the Gutman method.

    How good is that?
     
  15. Stryder Keeper of "good" ideas. Valued Senior Member

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    It should be good enough. It's really dependent on what you are storing and attempting to destroy, if it's just your family album and maybe a few pictures you aren't proud were taken then it will do the job, if it's something more impressive and likely to be confiscated for legal reasons or defence reasons then I can't technically tell you if it's good or not

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  16. Dr Mabuse Percipient Thaumaturgist Registered Senior Member

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    Not sure. Uninstall it, go download the latest version. Yours is badly out of date by now.

    Report back.
     
  17. river-wind Valued Senior Member

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    Stryder's right, shredding the data (shredder, cccleaner, etc) is a good idea. It may be overkill in many cases, but it doesn't hurt (unless you want to undelete a document later

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  18. Dr Mabuse Percipient Thaumaturgist Registered Senior Member

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    A true Gutmann wipe is overkill. That's more than enough. Gutmann was pretty much discredited for his assertions, but the idea of overkill seemed like a good idea for some uses so his multiple overlay wipes stay around. Kind of for the 'I'm paranoid so let's kick out the jams on this shit' approach.

    It is impossible to recover data after a Gutmann, but due to the 8 bit nature of storage addresses, 7 wipes is enough to be sure, hence the NSA uses that. You can't reassemble a byte of data to even begin to rebuild low-level pointer chains after 7 overwrites. The data is gone.
     
  19. spidergoat pubic diorama Valued Senior Member

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    A simple overwrite is plenty unless you are James Bond.
     
  20. S.A.M. uniquely dreadful Valued Senior Member

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    Thanks, I'm not James Bond, but I like to have options
     
  21. Michael 歌舞伎 Valued Senior Member

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    from wiki:

    Gutmann himself has responded to some of these criticisms and also criticized how his algorithm has been abused in an epilogue to his original paper, in which he states
    :
     
  22. vanesa7 Registered Senior Member

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    I think you can save all the files you like in reformatting your computer. It is up to you to decide.
     
  23. wynn ˙ Valued Senior Member

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    My computer has been formatted and reloaded three months ago.
    When I first ran CCleaner yesterday, I didn't check which version it was, but I clicked for updates.
    So now my version of the CCleaner is 2.34.1200, I have also checked for updates again.
    For this, I have worked from the administrator account.

    I still cannot go to the Advanced section to run Wipe Free Space.

    ?
     
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