Let me give you a hypothetical situation: you’re selling your computer on eBay or Craigslist and you clean out your hard drive so no one can get your personal information. You clean your hard drive by reformatting, removing the partition, or deleting all your personal files, moving it to the recycle bin, and emptying the recycle bin. The buyer of your computer, with some tech skills, could access all your data. How are we supposed to prevent our data that we destroyed from being recovered?
It’s recommended to wipe your hard drive securely before you get rid of it. The easiest way to do this on Windows, Mac, or Linux, is to use a program created for that purpose. On Mac, use Disk Utility to erase free space after you deleted your partition (you might need to use another disk or a Linux live CD). On Windows, try a utility like Delete Files Permanently (http://www.deletefilespermanently.com) or a free/open source equivalent. On Linux, there are multiple command line commands to wipe your disk (look here for the commands: http://stackoverflow.com/questions/85636/how-do-i-erase-my-disk-in-a-secure-way-ubuntu).
When wiping your disk, make sure that you use something that is Department of Defense compliant, which means more than 7 passes. The algorithm being Department of Defense compliant means it will be very secure in its deletion of data (by writing both random data it to this multiple times and also null bits and bytes).
Zach, why should I wipe my disk or at least wipe my free space even if I’m not trying to sell my computer? If you have any sensitive data on your computer, like banking information Social Security numbers, personal information, etc., the data can be recovered. To prove my point, I will relay an anecdote. The 3rd year after I got my IBM R51 ThinkPad, I went into a computer repair facility and had them try and recover some data. They didn’t find the data I needed, but they found data from three years prior (from the first day I turned on the computer).
To prevent data exposure if your computer ever gets stolen or if someone hacks into your computer and if you want a sense of security (that the documents and information that you wanted deleted is deleted), you should wipe your drive…or wipe the free space, if you still want to use the drive.
Here are some explanations:
Mac OS X:
Note: Lion has Zero, 3, and 7 not Zero, 7, and 35. Do 7 passes just like the video recommends.
Windows: http://www.deletefilespermanently.com/wipe_free_space.html.
Linux:
This might be able to help http://superuser.com/questions/19326/how-to-wipe-free-disk-space-in-linux.
Image Source: https://zysys.org//zycms/uploads/2012/02/hard-disk-data-recovery-servicepy1.jpg
