NIST Encryption Standards in Sanitation & Erasure

Here we take a look at 3 types of Sanitization according to SP 800-88 NIST Encryption Standards.

Clearing Clearing information is a level of media sanitization that would protect the confidentiality of information against a robust keyboard attack. Simple deletion of items would not suffice for clearing. Clearing must not allow information to be retrieved by data, disk, or file recovery utilities. It must be resistant to keystroke recovery attempts executed from standard input 7 Guidelines for Media Sanitization Type Description devices and from data scavenging tools. For example, overwriting is an acceptable method for clearing media. There are overwriting software or hardware products to overwrite storage space on the media with non-sensitive data. This process may include overwriting not only the logical storage location of a file(s) (e.g., file allocation table) but also may include all addressable locations. The security goal of the overwriting process is to replace written data with random data. Overwriting cannot be used for media that are damaged or not writeable. 

Purging Purging information is a media sanitization process that protects the confidentiality of information against a laboratory attack. For some media, clearing media would not suffice for purging. However, for ATA disk drives manufactured after 2001 (over 15 GB) the terms clearing and purging have converged. A laboratory attack would involve a threat with the resources and knowledge to use nonstandard systems to conduct data recovery attempts on media outside their normal operating environment. This type of attack involves using signal processing equipment and specially trained personnel. Executing the firmware Secure Erase command (for ATA drives only) and degaussing are examples of acceptable methods for purging. Degaussing of any hard drive assembly usually destroys the drive as the firmware that manages the device is also destroyed. Degaussing is exposing the magnetic media to a strong magnetic field in order to disrupt the recorded magnetic domains.

Destroying Destruction of media is the ultimate form of sanitization. After media are destroyed, they cannot be reused as originally intended. Physical destruction can be accomplished using a variety of methods, including disintegration, incineration, pulverizing, shredding, and melting. If destruction is decided upon due to the high security categorization of the information or due to environmental factors, any residual medium should be able to withstand a laboratory attack. ƒ Disintegration, Incineration, Pulverization, and Melting. These sanitization methods are designed to completely destroy the media. They are typically carried out at an outsourced metal destruction or incineration facility with the specific capabilities to perform these activities effectively, securely, and safely. ƒ Shredding. Paper shredders can be used to destroy flexible media such as diskettes once the media are physically removed from their outer containers. The shred size of the refuse should be small enough that there is reasonable assurance in proportion to the data confidentiality level that the information cannot be reconstructed. Optical mass storage media, including compact disks (CD, CD-RW, CD-R, CD-ROM), optical disks (DVD), and magneto-optic (MO) disks must be destroyed by pulverizing, 8 Guidelines for Media Sanitization Type Description crosscut shredding or burning. Destruction of media should be conducted only by trained and authorized personnel. Safety, hazmat, and special disposition needs should be identified and addressed prior to conducting any media destruction.