Securely erasing your old hard drive
A lot of buzz has been generated in recent years regarding identity theft and ways criminals are getting access to peoples private information. One method that criminals have used in the past is to buy used hard drives online and then recover the files with off the shelf software. I have personally purchased hard drives online that were supposedly ‘sanitized’ only to find someone elses files on the drive. Simply ‘deleting’ a file from your computer does not get rid of it permanently. What has occured when you hit the ‘delete’ key is that the file is no longer listed in the OS file system. However, the files still very much still exist on the drive.
The solution to the problem is to not only delete the files from the hard drive, but to also overwrite the data. By physically overwriting the files contents, you are ensuring that no remnant of the file remains behind. In fact, on modern hard drives manufactured within the past 10 to 15 years, there is NO known method (public or private sector) to recover a file that has been overwritten. One study suggested that “the chances of finding a single 4 letter word correctly from an overwritten Microsoft Word document file is 2.3166E-05 (0.00002317%)”.
Now that we have determined that overwriting our files is the way to go to ensure complete data destruction, what programs should we use? There are actually many programs available (both free and commercial) that will produce the same result. On newer hard drives, this feature is even built in to the drive itelf. The utility is called HDDErase and can be found here: http://cmrr.ucsd.edu/people/Hughes/SecureErase.shtml. Another tool commonly recommended is called DBAN and can be found at www.dban.org. For selected file erasure, I recommend either Eraser at http://eraser.heidi.ie/ or File Shredder at http://www.fileshredder.org/. Please use any of the above programs with a great deal of care as you will not be able to retrieve any files that these programs delete (kinda the point, right?)