Disposal
Disposal is the act of discarding media with no other sanitization considerations. This is
most often done by paper recycling containing non-confidential information but may also
include other media.
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 resistantto keystroke recovery attempts executed from standard input 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.
The media type and size may also influence whether overwriting is a suitable sanitization
method. [SP 800-36].
Studies have shown that most of today’s media can be effectively cleared by one overwrite.
Specific recommendations for clearing different media types are included in Appendix A