You own a computer and then purchased a new one. After moving all of your important data to the new computer and deciding to sell or donate the old computer you are faced with the question of deleting the data or destroying the hard drive. On one hand, if you delete the data and reinstall the operating system the next owner can quickly use the computer. If you destroy the hard drive, another drive would have to be installed for the computer to be useful again.
Now what can you do to avoid having your old ‘deleted’ data sniffed out? First you have to decide if you want to permanently erase the data or destroy the drive. If you decide to permanently erase the data, you have several options. However let’s go over what you DON’T want to do.
- Don’t just delete your data and empty the recycle bin
- Don’t just format the hard drive
- Don’t just format and reinstall Windows or another operating system
Why don’t you want to do the above? It seems this would be enough to make sure your data isn’t compromised.
Let’s take a step back and understand how data is stored on a hard drive. When information is written to a drive, the location of the information is stored in a file that resembles a table of contents for a book. On computers running DOS and Windows operating systems, the File Allocation Table (FAT) or the Master File Table (MFT) holds this information. When a file is deleted, the FAT or MFT table is updated to tell the computer the space on the hard drive is available, however the actual data is not deleted until it is overwritten with new data. This is why you read about computer forensic teams, the FBI, and other law enforcement being able to recover data to solve crimes or incriminate individuals. Using software undelete tools, you can restore files that were accidentally or otherwise deleted. In more severe case, services such as Drive Savers are used to recover data that has been physically or electronically destroyed.
Baring any of these extra efforts, you can use the procedures below to erase or destroy your data so the average individual won’t be able to recover anything from your computer hard drive.
Using Wipe Utilities
In order to prevent data from being recovered, you should use data wiping software to completely erase the information to Department of Defence (DOD) standards. I recommend the following free tools to sanitize or wipe a hard drive of information:
- Darik’s Boot and Nuke – a program that can be booted from floppy or CD to completely erase a hard drive
- Eraser by Heidi Computers Limited
- Active@ KillDisk
If you plan on giving your computer away, selling it, or otherwise disposing of it, please destroy the data on it by using one of the above wiping utilities.
Degaussing a Hard Drive
An extra step is to degauss the hard drive. Degaussing is a process whereby the magnetic media is erased using a reverse magnetic field to scramble the electronic data and make it unreadable. Unfortunately degaussing machines are rather expensive ($2000.00 or more) and are not realistic purchases for the average consumer. However, you can send your hard drive to a degaussing company like Garner Products or SEM and for a few dollars can have your hard drive completely degaussed and/or destroyed. If your data security is important enough, this is a wise step.
Physically Destroying a Hard DrivePhysically destroying a hard drive is by far the most effective method for the average person to ensure the safety of their data. However, please wear protective glasses and other gear if you decide to physically destroy a drive yourself. It can be a dangerous activity that I don’t recommend to everyone. Also, as a precaution, wrap the hard drive in a towel so the parts don’t fly off and do more damage.
Whether it’s smashing the hard drive with a sledgehammer, drilling holes into the drive, tearing the drive apart and destroying the platters, shredding the drive, or other methods your sensitive data will be safe.
For the most security, I recommend doing as many of the above procedures (wiping the drive, degaussing it, and destroying it) as you can. If a drive is wiped, degaussed, and destroyed the chances of recovering the data is almost nil.
If a computer store, consultant, or other qualified computer tech tells you your hard drive is crashed and the data is unrecoverable, ask for them to return the original drive to you. This way you can physically destroy and dispose of the drive to your satisfaction and avoid situations like Mr. Bowen’s where your data suddenly appears on someone else’s computer screen.