Securely Erasing Your Hard Drive
I have written several articles over the years about the importance of completely erasing personal data from hard drives before disposing of them. Savvy users understand that deleting a file doesn't really make it go away. And even formatting a hard drive doesn't guarantee that your files are unreadable. But here's some good news on that front...
When You Really Need to Wipe a Hard Drive...
My earlier article “Erasing a Hard Drive? Not So Fast…” delved into the difficulties of doing the job right. But now securely wiping a hard drive, or even a stubbornly data-persistent Solid State Drive (SSD), is easier than ever.
You probably know that the “delete” command doesn’t really delete the target data; it only deletes the location of that data from the hard drive’s index of files. After a “deletion,” the drive will re-use that file’s space as if it was empty.
But until data has been overwritten many times, it can still be recovered by a determined person. Military-grade standards call for overwriting each disk sector at least nine times before data stored in it can be considered truly “unrecoverable.” That takes a very long time, even on a 500 GB hard drive! Running a “secure erase” utility can tie up a computer for a day or even longer.
There is a solution, and you probably already have it. The firmware of nearly every hard drive built since 2001 contains a “Secure Erase” command so effective that NIST (the U.S. National Institute of Standards and Technology) rates it as good as degaussing a hard drive - that is, using a powerful magnet to completely scramble the bits stored on a drive. So why haven’t we been using “Secure Erase” for all these years?
Most BIOS developers disable the “Secure Erase” feature because they think consumers won’t use it wisely. Indeed, “SE,” as it’s called, is a “nuclear option.” It wipes data, and no amount of panicked, tearful phone calls to tech support or data recovery specialists will get it back. It even wipes data stored in bad disk blocks, something other disk-wiping utilities can’t do. When Secure Erase finishes its job, your hard drive will be squeaky clean, empty of all data, and ready to be used again. It Latin, that would be “tabula rasa.”
Unlock the Power
A freeware utility called HDDErase 4.0 unlocks the power of the Secure Erase feature in nearly every standard magnetic hard drive built since 2001. You can download it from the UC-San Diego’s Center for Memory and Recording Research, but note that no tech support is available and you use it at your own risk. Because it runs from a bootable disk, HDDErase can erase any operating system, using the drive's own built-in sanitizer. Tim Fisher’s review of HDDErase provides a little more insight into this powerful command-line utility.
I've read in various places that HDDErase will work on SSDs (solid state drives) in addition to traditional spinning magnetic hard drives. But the documentation for the program does not mention SSDs at all. However, this article on the Kingston Technology website seems authoritative, and does specifically mention using HDDErase with SSDs.
There is one important caveat, though, according to Kingston. HDDErase can only be run on hard drives that are directly attached to a SATA or IDE port, and not through a USB bridge or enclosure. Put more simply, HDDErase will ONLY work on internal drive, and WILL NOT work on external hard drives.
Another Secure Disk Wipe Option
If you have an external drive that you want to securely erase, or for some reason you'd rather not use the HDDErase utility, there's another way to get the job done.
Another method of rendering a drive forever unreadable is known as “Encrypt, Reformat, Encrypt Again.” First, encrypt your entire hard drive; Users running Windows 7 Ultimate, Windows 8.1 Pro, or Windows 10 Pro can use the built-in Bitlocker utility, if their PCs include a Trusted Platform Module (TPM) chip. Another alternative for encryption is the free VeraCrypt software, which works on Windows, Mac OS X and Linux computers.
Encrypting a working drive that contains lots of data may take many hours, but you’ll be able to work on other things while encryption proceeds in background. Once your drive is encrypted, do a FULL reformat of it. A “quick” format only wipes the index of files mentioned above, leading the drive to treat the whole disk as empty space. A full format overwrites all data.
Next, encrypt the reformatted drive AGAIN before adding any data to it. This won’t take long, because there is very little data to be encrypted. Now what do we have?
The re-encrypted, re-formatted drive has a security key that is required to decrypt data stored on the drive; the key is stored on the drive itself for Bitlocker to access on the fly. The security key of the first encryption has been overwritten during reformatting and encrypted by the second encryption. Even if a hacker recovers the second encryption key, he can’t recover the first one that might give him access to your old data. Now your drive is truly wiped and unrecoverable!
The Total Annihilation Method
It's good clean fun to use a drill press or sledge hammer on an unwanted hard drive (with the appropriate safety equipment). But if you lack those tools, a commercial hard drive shredding service will do the job. Ameri-Shred is one company that offers the service, and you can see their machinery in action in the video above.
Your thoughts on this topic are welcome. Post your comment or question below...
This article was posted by Bob Rankin on 9 Mar 2018
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Article information: AskBobRankin -- Securely Erasing Your Hard Drive (Posted: 9 Mar 2018)
Copyright © 2005 - Bob Rankin - All Rights Reserved