So you want to wipe your hard disk because you plan on selling or giving away your computer? Or you just want to make sure that all your important stuff is really gone. You may have even had a friend who is a “techie” come over and format your hard drive in preparation for installing a new OS. You feel safe, secure, warm, and fuzzy! You feel like everything is OK in the universe—your security is safe. Sorry to burst the bubble you have been living in, but you are more than likely not protected at all! Your personal information is still out there for the world to see—at least someone with the right tools and skills (which believe it or not are easily accessible and many times free!) What to do? Don’t worry, I am going to explain it to you.
To understand the problem you are facing we need a little lesson on how hard drives work. Hard drives are magnetic and the information is stored on very tiny magnetic rods on the surface of the hard drive platters. When the read/write head adds or removes information it aligns these microscopic rods by their poles (north or south). Depending on how the rods are aligned they represent either 1 or 0, binary language. When a file is added the read/write head aligns the rods. When files are deleted the rods are not realigned. The computer simply removes a reference to the file in the File Allocation Table (FAT). The data is still there, it’s just that your computer doesn’t realize it. This is the root of the problem. The FAT table can be rebuilt using easily attainable software and anyone can then see your information.
The solution to this problem is to overwrite the data that has been stored with random characters that are unintelligible and cannot be recovered. But even if you overwrite the data once or even twice the data can still be recovered. The Department of Defense’s policy on hard drive erasure is to overwrite at least three times. The National Security Agency (NSA) prefers to overwrite at least seven times! This makes sure the data is nearly impossible to recover. So what should you do? Ironically the technology to securely wipe your hard drive is already built in to your computer. Hard drive manufacturers started including a technology called Secure Erase in 2001 on all hard drives. Secure Erase is so effective that even the NSA uses the technology. Unfortunately the manufacturers of computer BIOS’s and the OS companies were not as forthcoming. The good news is you can take advantage of this technology.
How do you use Secure Erase? There are a few steps that you’ll have to take but you really don’t need to be a computer whiz to make it work:
The first, and perhaps still the best, piece of software to use is freeware called Secure Erase Utility (http://cmrr.ucsd.edu/Hughes/subpgset.htm). This program was actually developed by the same professor who created the Secure Erase feature on your hard drive. It does take a few steps such as creating an XP boot disc but if you take a look at the included README file it explains all the steps to use. This one might require a bit more computer knowledge but if you are willing to have a slight learning curve then this is your choice.
A second utility that you can use is Anti Tracks - Disk Wiper tool which support 4 secure erasing algorithms including the US Department of Defense DOD 5220.22-M, Gutmann and NSA in addition it allow you to build your own secure erasing schema with just few clicks. Anti Tracks might cost you few bucks for sure it will be worth the trip
Whatever you choose make sure that if you are looking to completely and securely erase your hard drive you don’t rely simply on a format utility since they DON’T securely erase anything. They just eliminate and rewrite the FAT table. Be safe!
