The rules for destroying sensitive or classified magnetic computer media, like hard drives and tape cartridges, can be confusing. But in actuality, the data destruction process can be boiled down to a simple procedure.
One question that often comes up is about what is and isn’t magnetic media. Magnetic media always involves a material with a surface that holds information in the form of magnetic traces. That includes standard hard drives, tape cartridges, Zip and Jaz disks, and jump drives. It does not include optical media (CD, DVD, BD) or solid state storage devices (SS hard drives, flash memory sticks, thumb drives, etc.). This is important to note, since degaussers are only useful for use on magnetic media. They can’t be used to wipe information off of optical or solid state storage devices.
There are two basic types of required equipment used for destroying magnetic media: degaussers and physical destroyers, like crushers or shredders. For users with government classified data, the choice is simple- the media must be wiped using an NSA listed degausser before disposal. The NSA mandates physical shredding or crushing as a process for final disposal of classified magnetic media. Approved degaussers can be identified by consulting the NSA Evaluated Products List or by looking at the SEM website under degaussers.
For unclassified media, a physical destroyer can be used as the sole destruction method. Devices that crush or shred hard drives and tape cartridges make these items extremely difficult to extract data from. A physical destruction method can be faster and lower cost than degaussing. This process is often seen as the best choice, when one is not concerned with an adversary with extensive resources available to recover data from scraps.
For classified data, physical destroyers is the step two after degaussing. Media looks no different after degaussing. It looks just like the original classified item. As an additional safeguard, the NSA mandates that all HDDs must be both degaussed and physically destroyed. That means that the hard drives can either be crushed or shredded by a product that is evaluated by the NSA and placed on the Evaluated Products List. SEM has examples of both, and you can see an example of a crusher and a shredder on our site.