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How to secure delete file or folder in windows?

I need to delete my data from the company laptop. Nothing special just 2 or 3 folders (I have Dropbox installed on this PC) and I'd like to be sure they are gone. I read about free tools and bootable CDs to erase the entire disk, I don't need those but just a free tool to put some zeros where my data were before.

O.S is Win XP

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marked as duplicate by Gnoupi Aug 10 '10 at 9:24

This question has been asked before and already has an answer. If those answers do not fully address your question, please ask a new question.

    
Please specify which OS you're using? –  Doug Harris May 20 '10 at 15:52
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6 Answers 6

up vote 2 down vote accepted

http://technet.microsoft.com/en-us/sysinternals/bb897443.aspx its free and as secure as it can get!

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How likely is that someone is going to spend time and money trying to recover your data?

If it's "not very" then just deleting the folders will be OK (even though it's not secure). As there'll be nothing obvious to indicate that there was ever anything there, unless someone suspects you're trying to hide something they'd have no reason to go snooping.

If your IT department is anything like the ones I've known they'll either re-image the disk or perform a format and clean install anyway before using the laptop again. In either case your data will be effectively gone.

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+1 While I agree that many IT departments will wipe, many do not and then a curious user finds your data. Also true that deleteing way too much will result in a more detailed examination of the device. –  Dave M May 20 '10 at 14:21
    
@DaveM - I wasn't suggesting microspino didn't delete at all, just that it might not be necessary to go the whole way and scrub the disk. –  ChrisF May 20 '10 at 14:50
    
I understood that. Sorry I was not more clear. Just saying in general. –  Dave M May 20 '10 at 15:01
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Under Linux, I'd suggest running

# changed form /dev/null to /dev/random per another suggestion
dd bs=128M count=8 if=/dev/random of=/tmp/blah0 
cp /tmp/blah /tmp/blah1
# repeat cp until drive full, then erase /tmp/blah* with 
rm -f /tmp/blah* &

Alternatively, download something like the Slax ISO. Then copy/paste it until your drive fills-up, deleting all copies before returning the laptop.

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I've used BCWipe. It's not a free, but it will wipe any free space (files you have deleted in the past but can still be recovered), file slacks (partial clusters at the end of files), swap space (windows virtual memory) and it's DoD approved.

(I think there is also free full featured demo)

If that's over killcheck out http://superuser.com/questions/86824/how-to-secure-delete-file-or-folder-in-windows

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Although I agree with ChrisF regarding the value of erasing your data, I've also known too many IT departments that would hand out an old PC without re-imaging it. And in this case, simply deleting folders and zeroing empty space isn't going to do what you want, because Windows applications tend to leave droppings all over the place.

So, assuming that you really want to protect yourself, and aren't prohibited from erasing the hard disk, you should download a bootable Linux install, such as Ubuntu.

At that point, you have several choices. First choice is to simply write zeros over the entire disk, including the partition table:

dd if=/dev/zero of=/dev/sda bs=8192

The only problem with this is that /dev/sda isn't guaranteed to be the hard disk, and unless you're familiar with Linux, it may not be obvious which device is the hard disk. So it's probably simpler to install Linux on the laptop, replacing whatever's there.

However, that won't guaranteed that someone can't pick up old files from the disk, so you'll need to zero all free space. Once you've installed, boot into Linux, and run the following:

dd if=/dev/zero of=/tmp/ix bs=8192
rm /tmp/ix

This is subtly different from what warren suggests: it uses dd to fill the entire free space with a single file. The cp command can create what are known as "sparse files," which do not actually consume disk blocks.

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Have used this for years.

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