Classified information is secret information to which access is restricted by law or corporate rules to a particular hierarchical class of people. A security clearance is permission to view a particular classified document or class of information, often requiring a satisfactory background check. This sort of hierarchical system of secrecy is used by virtually every national government, and by many corporations as well.

The desired degree of secrecy about such information is known as its sensitivity. It is often the case that sensitive information is disseminated on the basis of need-to-know, the assertion that if an individual needs to know certain information in order to satisfactorily perform her or his function in the organization, their viewing of that information is authorized, otherwise it is not.

Such information is called "classified" because it falls into a certain classification of secrecy. Information which isn't secret is called unclassified information, which carries the implication that the natural state of information is to be classified, in other words, to be made secret. While this phrase is doublespeak in general usage, it arises naturally as jargon for those who work with secrets on a daily basis. In such environments, one may assume that a document is classified for the same reason that one assumes that a gun is loaded. In general use, "unclassified" often refers to information which has recently had its classification removed, thus the media may speak of a "unclassified report."

The US Department of Defense, for example, has a formal hierarchy of classification for secrets:

• Top secret – this is the highest security level, and is defined as information which would cause "exceptionally grave damage" to national security if disclosed to the public. This classification is most often subdivided on the basis of "need to know", and includes such information as the design of cutting-edge weaponry, etc.

• Secret – the second highest classification may include, for example, details of other security measures and procedures. It is defined as information which would cause "serious damage" to national security if disclosed.

• Confidential – is the lowest classification level. It is defined as information which would "damage" national security if disclosed.

• Unclassified – not technically a "classification", this is the default, and refers to information which can be released to individuals without a clearance. Information which was previously classified under one of the above levels is often declared "unclassified" at a certain time because its age has made its classification no longer necessary. Past troop movements are one example; they may be of paramount importance before occurring, and shortly after, but ten years later will not require classification. There have been (controversial) attempts to make all information in certain nuclear-related fields classified from its origination; these have faced challenges in court. The Atomic Energy Act of 1954 is the law most often mentioned in this context. The fact that a document is unclassified does not necessarily mean it can be released to the public -- it can be restricted to certain distributions, but an individual doesn't have to be "cleared" to access it, only have a need-to-know. This type of data is commonly referred to as Sensitive but Unclassified (SBU)

Classified U.S. government documents are required to be stamped with their classification at the top and bottom of each page, and there are various other regulations for the handling and storage of such documents.

There are also compartments, or "code words", which pertain to specific projects, and are used to more easily manage which individuals require certain information. Code words are not levels of classification themselves, but a person working on project X may have the code word for that project added to his file, and then will be given access to the relevant documents. Code words may also label the sources of various documents; for example, there are code words used to indicate that a document may break the cover of intelligence operatives if its content becomes known. The WWII code word ULTRA identified information found by decrypting German ciphers, such as the Enigma machine, and which -- regardless of its own significance -- might inform the Germans that Enigma was broken if they became aware that it was known. In the Department of Defense, compartmentalized information is usually classified at Top Secret levels, but with the additional caveat of being Sensitive Compartmentalized Information or SCI.

The United States also has a system of "restrictions" which can be added to a document; these are constantly changing, but can include (in abbreviated form) a requirement that the document not be shared with civilian contractor, or not leave a specific room. Technically, one violating these directives would be guilty of violating a lawful order -- not the laws pertaining to the levels of classification -- and most of these designations do not appear in written law at all. Some of these include NOFORN, meaning no distribution to foreign nationals, NOCONTRATOR, meaning no distribution to contract personnel, and FOUO, or For Official Use Only.

It is also important to note that classifications and clearances do not transfer between various US government agencies. For example, an individual cleared for Department of Defense Top Secret must undergo another investigation before being granted a Department of Energy Q clearance.

Where information from different levels of classification or codeword sets is combined, the resulting information is given the most restrictive classification and label set from the original information.

Various UFO conspiracies mention a level "above top secret" used for UFO design information and related data; this is generally regarded as evidence of ignorance, since the levels of classification are themselves not secret. As such, the books available claiming to contain "above top secret" information on UFOs or remote viewing should arguably be taken with a grain of salt.

Contrary to popular lore, the Yankee White clearance given to personnel who work directly with the President is not a classification, but rather a type of investigation. Yankee White cleared personnel are granted access to any information for which they have a need-to-know, regardless of which organization classified it or at what level. [1]

The classification scheme of course varies between organizations; for example, in Canada information which the U.S. would classify SBU is called "protected," and further subcategorized into levels A, B, and C.

Trusted operating systems

Specialized computer operating systems known as trusted operating systems are available for processing classified information: they enforce the classification and labeling rules described above in software.

See also

• Work of the United States Government
• Official Secrets Act

External link

• US "NISPOM" manual, explaining rules on classified information among other things - full title is "National Industrial Security Program Operating Manual".
• Trusted operating systems