GEEK TOOL: Eraser

Many folks don’t know that when you delete a file in Windows, that file isn’t really “deleted”.

You see, Windows keeps track of everything on your hard drive using something called a “Master File Table” (MFT) or “File Allocation Table” (if you’re one of the 4 people left still running Windows 98 and the FAT32 file system). When you delete a file, the file’s entry in the MFT\FAT is erased, and the space is marked as “free”. But the actual data is still there, and it will remain there until it’s overwritten by a new file. And even when the data is overwritten, it’s possible for computer forensics types to figure out what files were originally there.

The only real way to “delete” a file in Windows is to take the space where the data was located and overwrite it with random data from 7 to 35 times. Some programs, like DBAN, will overwrite all the data on an entire hard drive, which is good for when you want to donate old computers to charity, and want to be 100% certain that any data on the drives is gone.

But what about securely erasing data on computers that you need to keep using? DBAN will wipe out an entire hard drive – thus rendering your computer useless. What if you want (or need) to securely delete just a few files? What if you work with medical patient information and need a means of completely removing any data files, but keeping all of your other files intact?

I like Eraser. This free, open-source program adds an “Erase” option to Windows Explorer’s context menu. Just select the file(s) you want to erase, then right-click and select “Erase”. Eraser will then overwrite the file(s) using the Guttmann, US DoD 5220-22.M method, or with pseudo-random data. It can also erase Internet Explorer’s index.dat file, “Temporary Internet Files” and cookies, erase free space, erase the contents of the Recycle Bin, erase network files, floppy disks, CD-RW, DVD-RAM and DVD-RW discs, and erase the page (swap) file. Oh, and it works with Windows 95, 98, ME, NT, 2000, XP and DOS! It’s a great little program – did I mention that it’s also free? – and is a quick and easy way to remove any trace of files on your computer!

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