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标 题: wikipedia关于clearance的介绍
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A typical classified document. Page 13 of a U.S. National Security Agency
report  on the USS Liberty incident, partially declassified and released to
the public in July 2003. The original overall classification of the page, "
top secret" code word "umbra," is shown at top and bottom. The classification
of individual paragraphs and reference titles is shown in parentheses - there
are six different levels on this page alone. Notations with leader lines at
top and bottom cite statutory authority for not declassifying certain sections
.Classified information is information to which access is restricted by law or
regulation to particular classes of people. A formal security clearance is
required to handle classified documents or access classified data; the
clearance process requires a satisfactory background investigation. There are
typically several levels of sensitivity, with differing clearance requirements
. This sort of hierarchical system of secrecy is used by virtually every
The purpose of classification is ostensibly to protect information from being
used to damage or endanger national security. Classification formalizes what
constitutes a "state secret" and accords different levels of protection based
on the expected damage the information might cause in the wrong hands.
1 Corporate classification
2 U.S. Government's classification system
2.1 Accessing Classified Information
2.2 Classified vs. Unclassified Information
2.3 Levels of Classification used by the U.S. Government
2.3.1 Top secret
2.3.6 Above Top Secret?
2.4 Proper procedure for classifying U.S. government documents
2.5 Protecting classified information
2.6 Classifications and clearances between U.S. government agencies
2.7 Categories that are not classifications
2.7.1 Restricted data
2.7.2 Critical Nuclear Weapon Design Information
2.7.3 Naval Nuclear Propulsion Information
2.7.4 Yankee White Clearance
2.8 Claims of U.S. government misuse of the classification system
3 Classifications in other countries
3.1 Sharing of classified information between countries
3.2 Table of equivalent classification markings in various countries
4 See also
4.1 United States practice
5 External links and references
Private corporations often require written confidentiality agreements and
conduct background checks on candidates for sensitive positions.  In the U.
S. the Employee Polygraph Protection Act prohibits private employers from
requiring lie detector tests, but there are a few exceptions. Policies
dictating methods for marking and safeguarding company-sensitive information (
e.g. "IBM Confidential") are common and some companies have more than one
level. Such information is protected under trade secret laws. New product
development teams are often sequestered and forbidden to share information
about their efforts with un-cleared fellow employees, the original Apple
Macintosh project being a famous example. Other activities, such as mergers
and financial report preparation generally involve similar restrictions.
However, corporate security generally lacks the elaborate hierarchical
clearance and sensitivity structures and the harsh criminal sanctions that
give government classification systems their particular tone.
EDS uses three classifications of information. Disclosure of EDS Limited
Distribution information could cause serious damage to an affected party.
Disclosure of EDS Confidential information could damage an affected party.
Disclosure of EDS Internal information (most EDS business information) could
be inappropriate or problematic.
U.S. Government's classification system
The United States Government classification system is established under
Executive Order 13292, the latest in a long series of executive orders on the
topic. Issued by President George W. Bush in 2003, Executive Order 13292 lays
out the system of classification, declassification and handling of national
security information generated by the United States Government and its
employees and contractors, as well as information received from other
The desired degree of secrecy about such information is known as its
sensitivity. Sensitivity is based upon a calculation of the damage to national
security that the release of the information would cause. The United States
has three levels of classification — confidential, secret, and top secret.
Each level of classification indicates an increasing degree of sensitivity.
Thus if one holds a top-secret clearance, one is allowed to handle information
up to the level of "top-secret" including secret, and confidential
information. If one holds a secret clearance, one may not then handle top-
secret information, but may handle confidential classified information.
In the United States, information cannot be classified merely because it would
be embarrassing; information can only be classified in relationship to
protecting national security objectives of the state.
Accessing Classified Information
In addition to sensitivity level, information that is classified is restricted
in its dissemination based on the "need to know" the information. Having a "
top-secret" clearance does not give one access to all documents classified at
that level. Rather, information is disseminated based upon sensitivity level
and the need to know. In addition, dissemination of information is often
compartmentalized, requiring special additional clearance requirements.
Individuals with access to one type of compartmentalized information may, for
that reason alone, be denied access to other compartmentalized information.
Individuals who need access to the most sensitive intelligence information
hold a "TS/SCI" clearance — Top-Secret/Sensitive Compartmentalized
Information. In addition, there are Special Access Programs or "SAPs" that
restrict access to all information relating to that program or project to a
limited number of pre-approved people.
Classified vs. Unclassified Information
In the U.S. information is called "classified" because it has been assigned
one of the three levels, confidential, secret or top secret. Information which
is not so labeled is called unclassified information. The term declassified
is used for information which has had its classification removed, and
downgraded refers to information that has been assigned a lower classification
level, but is still classified. Many documents are automatically downgraded
and then declassified after some number of years. The U.S. government uses the
term sensitive but unclassified (SBU) to refer to information that is not
confidential, secret or top secret, but whose dissemination is still
restricted. Reasons for such restrictions can include export controls, privacy
regulations, court orders, and ongoing criminal investigations as well as
national security. Information which was never classified is sometimes
referred to as "open source" by those who work in classified activities.
Levels of Classification used by the U.S. Government
The United States Government classifies information according to the degree
which the unauthorized disclosure would damage national security:
This is the highest security level that is publicly disclosed, and is defined
as information which would cause "exceptionally grave damage" to national
security if disclosed to the public. Despite public mystique, little
information is classified at "Top Secret" when compared to the other levels of
classification. Only that which is exceptionally sensitive (weapon design,
presidential security information, nuclear-related projects, various
intelligence information) is classified at the Top Secret level. Other times,
the nature of the gathering method used to obtain the information is what
causes the information to be classified "Top Secret", though the information
itself may be mundane and unimportant. Examples would be signal interceptions
(SIGINT) or Human Intelligence (HUMINT).
The second highest classification. Information is classified secret when its
release would cause "serious damage" to national security. Most information
that is classified is held at the secret sensitivity.
The lowest classification level. It is defined as information which would "
damage" national security if disclosed.
Unclassified is not technically a "classification", this is the default, and
refers to information which can be released to individuals without a clearance
. Information that is unclassified is sometimes restricted in its
dissemination as SBU or FOUO, For Official Use Only. For example, the "law
enforcement bulletins" often reported by the U.S. media when United States
Department of Homeland Security raises the U.S. terror threat level are
usually classified as "U//LES" or "Unclassified - Law Enforcement Sensitive."
This information is only supposed to be released to Law Enforcement groups (
Sheriff, Police, etc.) Because the information is unclassified, however, it is
sometimes released to the public as well. Information which is unclassified,
but which the government does not believe should be subject to Freedom of
Information Act requests is often classified as U//FOUO - Unclassified-For
Official Use Only. In addition to FOUO information, information can be
categorized according to its availability to be distributed (Distribution D
may only be released to approved Department of Defense and Government
Contractor persons). Also, the statement of NOFORN (meaning No Foreign
Nationals) is applied to any information which may not be released to any non-
US Citizen. NOFORN and Distribution statements are often used in conjunction
with classified information or alone on SBU information. Documents subject to
export controls have a specific warning to that effect.
Use of information restrictions outside the classification system is growing
in the U.S. government. In September 2005, J. William Leonard, director of the
U.S. National Archives Information Security Oversight Office was quoted in
the press as saying "No one individual in government can identify all the
controlled, unclassified [categories], let alone describe their rules." 
During and before World War II, the U.S. had a category of classified
information called restricted, which was below confidential. The U.S. no
longer has a restricted classification, but many other nations and NATO do.
The U.S. treats "restricted" information it receives from other governments as
confidential. The U.S. does use the term restricted data in a completely
different way to refer to nuclear secrets, as described below.
Above Top Secret?
A common question about U.S. classified information is whether a level above
Top Secret exists. Looked at one way, the answer is almost certainly no.
Executive Order 13292 clearly states the Top Secret is the highest level of
classification. If there were some secret Executive Order that created a still
higher level, there could be questions of adequate legal notice if someone
mishandling that information were to be prosecuted. On the other hand, if a U.
S. government agency wants to create a program so secret that the program's
name itself is known to only a short list of hand picked individuals who have
been recently subjected to the most thorough and intrusive vetting process
imaginable, they can do so under the code word and special access provisions
of Executive Order 13292. Stringent additional security measures beyond those
prescribed for ordinary Top Secret can also be required for the program, which
would none the less still be classified at the Top Secret level, but with a
code name and other markings added. As a practical matter the distinction is
Proper procedure for classifying U.S. government documents
To be properly classified, a classification authority (an individual charged
by the U.S. Government with the right and responsibility to properly determine
the level of classification and the reason for classification) must determine
the appropriate classification level as well as the reason information is to
be classified. A determination must be made as to how and when the document
will be declassified and the document marked accordingly. Executive Order
13292 describes the reasons and requirements for information to be classified
and declassified. Individual agencies within the government develop guidelines
for what information is classified and at what level.
Protecting classified information
GSA approved security container.One of the reasons for classifying state
secrets into sensitivity levels is to allow the level of protection to be
tailored to risk. The U.S. government specifies in some detail the procedures
for protecting classified information. The rooms or buildings where classified
material is stored or handled must have a facility clearance at the same
level as the most sensitive material to be handled. Good quality commercial
physical security standards generally suffice for lower levels of
classification; at the highest levels, people sometimes have to work in rooms
designed like bank vaults (see SCIF). The U.S. General Services Administration
sets standards for locks and containers used for storage of classified
material. The most ubiquitous approved security containers look like heavy
duty file cabinets with a combination lock in the middle of one drawer.
Advances in methods for defeating mechanical combination locks have lead the U
.S. government to switch to electro-mechanical locks that limit the rate at
which combinations can be tried out.
Secret cover sheet. Top secret documents have an orange border and
confidential documents have blue.Classified U.S. government documents are
typically required to be stamped with their classification on the cover and at
the top and bottom of each page. It is often a requirement that each
paragraph, title and caption in a document be marked with the highest level of
information it contains, usually by placing appropriate initials in
parentheses at the beginning (or sometimes end) of the paragraph. It is common
to require a brightly-colored cover sheet be affixed to the cover each
classified document, to prevent observation of a possibly classified title by
someone unauthorized (shoulder surfing) and to remind users to lock up the
document when it is unattended. The most sensitive material requires two
person integrity, where two cleared individuals are responsible for the
material at all times. Approved containers for such material have two separate
combination locks, both of which must be opened to access the contents.
There are restrictions on how classified documents can be shipped. Top secret
material must go by special courier. Secret material can be sent within the U.
S. via registered mail, and confidential material by certified mail.
Electronic transmission of U.S. classified information requires the use of
National Security Agency approved encryption systems.
Specialized computer operating systems known as trusted operating systems are
available for processing classified information. These enforce the
classification and labeling rules described above in software. However, as of
2005 they are not considered secure enough to allow uncleared users to share
computers with classified activities. Computer networks for sharing classified
information, such as SIPRNet, are segregated by the highest sensitivity level
they are allowed to transmit.
The destruction of classified documents requires burning, shredding, pulping
or pulverizing using approved procedures and must be witnessed and logged.
Classified computer data presents special problems. See Data remanence
Classifications and clearances between U.S. government agencies
In the past, clearances did not necessarily transfer between various U.S.
government agencies. For example, an individual cleared for Department of
Defense Top Secret had to undergo another investigation before being granted a
Department of Energy Q clearance. Agencies are now supposed to honor
background investigations by other agencies, if they are still current.
Because most security clearances only apply inside the agency where the holder
works, if one needs to meet with another agency to discuss classified matters
, it is possible and necessary to "pass" one's clearance to the other agency.
For example, officials visiting at the White House from other government
agencies would pass their clearances to the Executive Office of the President
Categories that are not classifications
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.
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. Some of these include NOFORN, meaning no
distribution to foreign nationals, NOCONTRACTOR, meaning no distribution to
contract personnel, CRYPTO, meaning methods involved in encrypting
communications between government agencies, and CCO, meaning handle by COMINT
(communications intelligence) channels only. These restrictions are not
classifications in and of themselves, rather, they restrict the dissemination
of information within those who have the appropriate clearance level and
possibly the "need to know" the information. Remarks such as "eyes only" also
limit the restriction. One violating these directives might be guilty of
violating a lawful order or mishandling classified information.
The Atomic Energy Act of 1954 sets requirements for protection of information
about nuclear weapons and special nuclear materials. Such information is "
classified from birth," unlike all other sensitive information which must be
classified by some authorized individual. Documents containing such
information must be marked "RESTRICTED DATA" (RD) or "FORMERLY RESTRICTED DATA
" (FRD) in addition to any other classification marking. Persons accessing
such data require special clearances from the U.S. Department of Energy. For
example, a Q clearance is required for access to Top Secret-Restricted Data.
Critical Nuclear Weapon Design Information
Critical Nuclear Weapon Design Information (CNWDI) is a U.S. Department of
Defense category of TOP SECRET Restricted Data or SECRET Restricted Data that
reveals the theory of operation or design of the components of a nuclear
weapon. Access to CNWDI is supposed to be kept to the minimum number of
Naval Nuclear Propulsion Information
While most Naval Nuclear Propulsion Information is sensitive, it may or may
not be classified. The United States Navy recognizes that the public has an
interest in environmental, safety, and health information, and that the basic
research the Navy carries out can be useful to industry.
Yankee White Clearance
Contrary to popular lore, the Yankee White clearance given to personnel who
work directly with the President is not a classification. Individuals having
Yankee White clearances undergo extensive background 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. The Yankee White clearance includes a requirement for absolute absence
of any foreign influence on the individual. This means they must be a natural
-born citizen of the United States, not be or have been married to a person of
foreign descent, or have travelled to countries that are considered to be
unfriendly to the United States. 
Claims of U.S. government misuse of the classification system
While the classification of information by the government is not supposed to
be used to prevent information from being made public that would be simply
embarrassing or reveal criminal acts, it has been alleged that the government
routinely misuses the classification system to coverup misdeeds. See, for
example, The Pentagon Papers. Many conspiracy theories such as the JFK
assassination theories suggest that the government has classified information
as top secret that reveals the involvement of agencies such as the CIA.
Various UFO conspiracies mention a level "above top secret" used for UFO
design information and related data. They suggest such a classification is
intended to apply to information relating to things whose possible existence
is to be denied, such as aliens, as opposed to things whose potential
existence may be recognized, but for which access to information regarding
specific programs would be denied as classified. The existence of an “above
top secret” classification is considered by some as unnecessary to keep the
existence of aliens a secret, as they say Information at the "Top Secret"
level, or any level, can be restricted on the basis of need-to-know. Thus, the
U.S. Government could conceal an alien project without having to resort to
another level of clearance. The "need to know" would limit the ability to have
access to the information. Some suggest that claims of the existence of such
a classification level may be based on the mistaken belief that the ‘’levels
’’ of classification are themselves classified: As such they feel that books
available claiming to contain "above top secret" information on UFOs or
remote viewing should arguably be taken with a grain of salt.
Classifications in other countries
Facsimile of the cover page from an East German operation manual for the M-125
Fialka cipher machine. The underlined classification markings can be
translated as "Cryptologic material! Secret classified material" .Most
countries employ some sort of classification system for certain government
information. For example, in Canada information which the U.S. would classify
SBU is called "protected" and further subcategorized into levels A, B, and C.
New Zealand has an additional grade known as Restricted, which is lower than
Confidential. Information with a Restricted classification is not for general
dissemination, but is not classified in the strictest sense of the word - it
is often used for controlling the release of reports and other documents until
it can be done officially. People may be given access to Restricted and
Confidential information on the strength of an authorisation by their Head of
Department, without being subjected to the background vetting associated with
Secret and Top Secret clearances. New Zealand's security classifications and
the national-harm requirements associated with their use are roughly similar
to those of the United States.
Australia also has the classification grade of RESTRICTED. Similar in intent
to New Zealand in regards as 'not for general dissemination' it is still a
classification level in Federal Government. Background checks are done for
this level, although not to the extent as higher classifications.
Australia also has a non-national security based classification system that is
used in areas of the Federal Government not directly related to national
security matters. This system is used for information whose compromise would
not directly threaten the security of the nation, but the release of which
could threaten the security or interests of individuals, groups, commercial
entities, government business and interests, or the safety of the community
HIGHLY PROTECTED—which broadly corresponds to SECRET in the national security
PROTECTED —which broadly corresponds to CONFIDENTIAL in the national security
'X'-IN-CONFIDENCE — which broadly corresponds to RESTRICTED in the national
In addition, documents marked 'CABINET-IN-CONFIDENCE', relating to discussions
in Federal Cabinet, are treated as PROTECTED.
Sharing of classified information between countries
When a government agency or group shares information between an agency or
group of other country’s government they will generally employ a special
classification scheme which both parties have previously agreed to honor. For
example, sensitive information shared amongst NATO allies has four levels of
security classification; COSMIC TOP SECRET (CTS), NATO SECRET (NS), NATO
CONFIDENTIAL (NC), and NATO RESTRICTED (NR). Another marking, ATOMAL, is
applied to U.S. RESTRICTED DATA or FORMERLY RESTRICTED DATA and United Kingdom
Atomic information that has been released to NATO. ATOMAL information is
marked COSMIC TOP SECRET ATOMAL (CTSA), NATO SECRET ATOMAL (NSA), or NATO
CONFIDENTIAL ATOMAL (NCA).
In cases where the United States wishes to share classified information
bilaterally (or multilaterally) with a country that has a sharing agreement,
the information is marked "REL" (release) and the three-letter country code.
For example, if the U.S. wanted to release classified information to the
governments of France, UK, and Canada, it would mark the document "REL FRA,
GBR, CAN." Those countries would have to maintain the classification of the
document at the level originally classified (TOP-SECRET, SECRET, etc.). The
United States has military and national security information sharing
agreements with most of its allies.
Table of equivalent classification markings in various countries
Argentina Estrictamente Secreto Secreto Confidencial Reservado
Australia Top Secret Secret Confidential Restricted
Austria Streng Geheim Geheim Verschluss
Belgium (Flemish) Zeer Geheim Geheim Vertrouwelijk Beperkte
or Muy Secreto Secreto Confidencial Reservado
Brazil Ultra Secreto Secreto Confidencial Reservado
Bulgaria Строго секретно Секретно Поверително
За служебно ползване
Cambodia Sam Ngat Bamphot Sam Ngat Roeung Art Kambang Ham Kom Psay
Canada Top Secret Secret Confidential Restricted
Chile Secreto Secreto Reservado Reservado
Columbia Ultrasecreto Secreto Reservado Confidencial
Costa Rica Alto Secreto Secreto Confidencial
Denmark Yderst Hemmeligt Hemmeligt Fortroligt Tiltjenestebrug
Ecuador Secretisimo Secreto Confidencial Reservado
El Savador Ultra Secreto Secreto Confidencial Reservado
Ethiopia Yemiaz Birtou Mistir Mistir Kilkil
Finland Erittäin Salainen Salainen Luottamuksellinen
France Tres Secret Secret Defense Confidentiel Defense Diffusion Restreinte
Germany Streng Geheim Geheim VS-Vertraulich VS-Nur für den
Greece Άκρως Απόρρητον Απόρρητον Εμπ
Guatemala Alto Secreto Secreto Confidencial Reservado
Haiti Top Secret Secret Confidential Reserve
Hinduras Super Secreto Secreto Confidencial Reservado
Hong Kong Top Secret Secret Confidential Restricted
Hungary Szigoruan Titkos Titkos Bizalmas
India Param Gupt Gupt Gopniya Pratibanhst/seemit
Indonesia Sangat Rahasia Rahasia Agak Rahasia Terbatas
Iran Bekoliserri Serri Kheil Mahramaneh Mahramaneh
Iraq Sirri Lil-ghaxah Sirri Khass Mehdoud
Ireland Algjorti Trunadarmal
Ireland (Gaelic) An-sicreideach Sicreideach Runda Srianta
Israel Sodi Beyoter
סודי ביותר Sodi
Italy Segretissimo Segreto Riservatissimo Riservato
Japan Kimitsu Gokuhi Hi Toriaatsukkaichui
Jordan Maktum Jiddan Maktum Sirri Mahdud
Korea I-Kup Bi Mil II-Kup Bi Mil III-Kup Bi Mil Bu Woi Bi
Laos Lup Sood Gnod Kuam Lup Kuam Lap Chum Kut Kon Arn
Lebanon Tres Secret Secret Confidentiel
Mexico Alto Secreto Secreto Confidencial Restringido
Netherlands Zeer Geheim Geheim Confidentieel or Vertrouwelijk Dienstgeheim
New Zealand Top Secret Secret Confidential Restricted
Nicaragua Alto Secreto Secreto Confidencial Reservado
Norway Strengt Hemmelig Hemmelig Konfidensiell Begrenset
Pakistan (URDU) Intahai Khufia Khufia Sigh-E-Raz Barai Mahdud Taqsim
Paraguay Secreto Secreto Confidencial Reservado
Peru Estrictamente Secreto Secreto Confidencial Reservado
Philippines Top Secret Secret Confidential Restricted
Portugal Muito Secreto Secreto Confidencial Reservado
Republic of Moldova De importanţă deosebită Strict Secret
Secret Pentru uz de serviciu
Russia Совершенно Секретно Секретно не подле
жит оглашению (Конфиденциально) Для Служеб
Saudi Arabia Saudi Top Secret Saudi Very Secret Saudi Secret Saudi Restricted
Spain Maximo Secreto Secreto Confidencial Diffusion Limitada
(thick red border) Hemlig
(thin red border)
Switzerland Geheim Vertraulich Armee intern
Taiwan Chichimi Chimi
Thailand Lup Tisud Lup Maag Lup Pok Pid
Turkey Cok Gizli Gizli Ozel Hizmete Ozel
South Africa (English) Top Secret Secret Confidential Restricted
South Africa(Afrikaans) Uiters Geheim Geheim Vertroulik Beperk
United Arab Republic of Egypt Jirri Lilghaxeh SirriKhas Mehoud Jidden
United Kingdom Top Secret Secret Confidential Restricted
United States Top Secret Secret Confidential
Uraguay Ultra Secreto Secreto Confidencial Reservado
Viet Nam Toi-Mat Mat Kin Pho Bien Han Che
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