How to Clear Your Computer’s Hard Drive of Personal Data
I know that some of us will be donating or disposing of our computers this year. I hope that each of you has considered that your personal information may be visible on your computer’s hard drive, even after you have deleted it. The data is actually still there and can be accessed by savvy computer users for malicious purposes.
When you delete files, all you are really doing is telling your operating system to clear out its table of contents of those files. It doesn’t “zero out”, or “blank” the files as you might guess. You are essentially giving your OS permissions to write over the files you told it to delete. Since you deleted them, you told the OS you don’t need them, and therefore it can reclaim that space and report back to you the new “free space” size. In reality, all the data is still there and anybody with an undelete program downloaded from the Internet can recover some or even all of the data (including you photos, saved browser passwords, bank info, social security number, etc…) But don’t fret; you can still give away that computer safely.
Windows and Linux Users
To ensure that your data is wiped clean, use Darik’s Boot and Nuke. This is a free download that installs on a floppy or USB drive. Once installed, you can boot your computer to that floppy or USB drive and begin to wipe. Darik’s Boot and Nuke does an effective job of writing and overwriting the data multiple times with random 1s and 0s. This process will leave no recognizable files or folders left on the hard drive.
Mac OS X 10.4 has a built in disk utility that can securely erase your hard drives. If you want to erase the System Disk, you will need to boot your OS X Install CD first. More info for Mac Users can be found here.
Do you know of any good data erasure tools?