$ card copy
See: token copy.
$ card restore
See: token restore.
$ cardholder
(I) An entity that has been issued a card.
(O) SET usage: "The holder of a valid payment card account and
user of software supporting electronic commerce." [SET2] A
cardholder is issued a payment card by an issuer. SET ensures that
in the cardholder's interactions with merchants, the payment card
account information remains confidential. [SET1]
$ cardholder certificate
(O) SET usage: A digital certificate that is issued to a
cardholder upon approval of the cardholder's issuing financial
institution and that is transmitted to merchants with purchase
requests and encrypted payment instructions, carrying assurance
that the account number has been validated by the issuing
financial institution and cannot be altered by a third party.
[SET1]
$ cardholder certification authority (CCA)
(O) SET usage: A CA responsible for issuing digital certificates
to cardholders and operated on behalf of a payment card brand, an
issuer, or another party according to brand rules. A CCA maintains
relationships with card issuers to allow for the verification of
cardholder accounts. A CCA does not issue a CRL but does
distribute CRLs issued by root CAs, brand CAs, geopolitical CAs,
and payment gateway CAs. [SET2]
$ CAST
(N) A design procedure for symmetric encryption algorithms, and a
resulting family of algorithms, invented by C.A. (Carlisle Adams)
and S.T. (Stafford Tavares). [R2144, R2612]
$ category
(I) A grouping of sensitive information items to which a non-
hierarchical restrictive security label is applied to increase
protection of the data. (See: compartment.)
$ CAW
See: certification authority workstation.
$ CBC
See: cipher block chaining.
$ CCA
See: cardholder certification authority.
$ CCITT
(N) Acronym for French translation of International Telephone and
Telegraph Consultative Committee. Now renamed ITU-T.
$ CERT
See: computer emergency response team.
$ certificate
(I) General English usage: A document that attests to the truth of
something or the ownership of something.
(C) Security usage: See: capability, digital certificate.
(C) PKI usage: See: attribute certificate, public-key certificate.
$ certificate authority
(D) ISDs SHOULD NOT use this term because it looks like sloppy use
of "certification authority", which is the term standardized by
X.509.
$ certificate chain
(D) ISDs SHOULD NOT use this term because it duplicates the
meaning of a standardized term. Instead, use "certification path".
$ certificate chain validation
(D) ISDs SHOULD NOT use this term because it duplicates the
meaning of standardized terms and mixes concepts in a potentially
misleading way. Instead, use "certificate validation" or "path
validation", depending on what is meant. (See: validate vs.
verify.)
$ certificate creation
(I) The act or process by which a CA sets the values of a digital
certificate's data fields and signs it. (See: issue.)
$ certificate expiration
(I) The event that occurs when a certificate ceases to be valid
because its assigned lifetime has been exceeded. (See: certificate
revocation, validity period.)
$ certificate extension
See: extension.
$ certificate holder
(D) ISDs SHOULD NOT use this term as a synonym for the subject of
a digital certificate because the term is potentially ambiguous.
For example, the term could also refer to a system entity, such as
a repository, that simply has possession of a copy of the
certificate. (See: certificate owner.)
$ certificate management
(I) The functions that a CA may perform during the life cycle of a
digital certificate, including the following:
- Acquire and verify data items to bind into the certificate.
- Encode and sign the certificate.
- Store the certificate in a directory or repository.
- Renew, rekey, and update the certificate.
- Revoke the certificate and issue a CRL.
(See: archive management, certificate management, key management,
security architecture, token management.)
$ certificate owner
(D) ISDs SHOULD NOT use this term as a synonym for the subject of
a digital certificate because the term is potentially ambiguous.
For example, the term could also refer to a system entity, such as
a corporation, that has acquired a certificate to operate some
other entity, such as a Web server. (See: certificate holder.)
$ certificate policy
(I) "A named set of rules that indicates the applicability of a
certificate to a particular community and/or class of application
with common security requirements." [X509] (See: certification
practice statement.)
(C) A certificate policy can help a certificate user decide
whether a certificate should be trusted in a particular
application. "For example, a particular certificate policy might
indicate applicability of a type of certificate for the
authentication of electronic data interchange transactions for the
trading goods within a given price range." [R2527]
(C) A v3 X.509 public-key certificate may have a
"certificatePolicies" extension that lists certificate policies,
recognized by the issuing CA, that apply to the certificate and
govern its use. Each policy is denoted by an object identifier and
may optionally have certificate policy qualifiers.
(C) SET usage: Every SET certificate specifies at least one
certificate policy, that of the SET root CA. SET uses certificate
policy qualifiers to point to the actual policy statement and to
add qualifying policies to the root policy. (See: SET qualifier.)
$ certificate policy qualifier
(I) Information that pertains to a certificate policy and is
included in a "certificatePolicies" extension in a v3 X.509
public-key certificate.
$ certificate reactivation
(I) The act or process by which a digital certificate, which a CA
has designated for revocation but not yet listed on a CRL, is
returned to the valid state.
$ certificate rekey
(I) The act or process by which an existing public-key certificate
has its public key value changed by issuing a new certificate with
a different (usually new) public key. (See: certificate renewal,
certificate update, rekey.)
(C) For an X.509 public-key certificate, the essence of rekey is
that the subject stays the same and a new public key is bound to
that subject. Other changes are made, and the old certificate is
revoked, only as required by the PKI and CPS in support of the
rekey. If changes go beyond that, the process is a "certificate
update".
(O) MISSI usage: To rekey a MISSI X.509 public-key certificate
means that the issuing authority creates a new certificate that is
identical to the old one, except the new one has a new, different
KEA key; or a new, different DSS key; or new, different KEA and
DSS keys. The new certificate also has a different serial number
and may have a different validity period. A new key creation date
and maximum key lifetime period are assigned to each newly
generated key. If a new KEA key is generated, that key is assigned
a new KMID. The old certificate remains valid until it expires,
but may not be further renewed, rekeyed, or updated.
$ certificate renewal
(I) The act or process by which the validity of the data binding
asserted by an existing public-key certificate is extended in time
by issuing a new certificate. (See: certificate rekey, certificate
update.)
(C) For an X.509 public-key certificate, this term means that the
validity period is extended (and, of course, a new serial number
is assigned) but the binding of the public key to the subject and
to other data items stays the same. The other data items are
changed, and the old certificate is revoked, only as required by
the PKI and CPS to support the renewal. If changes go beyond that,
the process is a "certificate rekey" or "certificate update".
$ certificate request
(D) ISDs SHOULD NOT use this term because it looks like imprecise
use of a term standardized by PKCS #10 and used in PKIX. Instead,
use the standard term, "certification request".
$ certificate revocation
(I) The event that occurs when a CA declares that a previously
valid digital certificate issued by that CA has become invalid;
usually stated with a revocation date.
(C) In X.509, a revocation is announced to potential certificate
users by issuing a CRL that mentions the certificate. Revocation
and listing on a CRL is only necessary before certificate
expiration.
$ certificate revocation list (CRL)
(I) A data structure that enumerates digital certificates that
have been invalidated by their issuer prior to when they were
scheduled to expire. (See: certificate expiration, X.509
certificate revocation list.)
(O) "A signed list indicating a set of certificates that are no
longer considered valid by the certificate issuer. After a
certificate appears on a CRL, it is deleted from a subsequent CRL
after the certificate's expiry. CRLs may be used to identify
revoked public-key certificates or attribute certificates and may
represent revocation of certificates issued to authorities or to
users. The term CRL is also commonly used as a generic term
applying to all the different types of revocation lists, including
CRLs, ARLs, ACRLs, etc." [FPDAM]
$ certificate revocation tree
(I) A mechanism for distributing notice of certificate
revocations; uses a tree of hash results that is signed by the
tree's issuer. Offers an alternative to issuing a CRL, but is not
supported in X.509. (See: certificate status responder.)
$ certificate serial number
(I) An integer value that (a) is associated with, and may be
carried in, a digital certificate; (b) is assigned to the
certificate by the certificate's issuer; and (c) is unique among
all the certificates produced by that issuer.
(O) "An integer value, unique within the issuing CA, which is
unambiguously associated with a certificate issued by that CA."
[X509]
$ certificate status responder
(N) FPKI usage: A trusted on-line server that acts for a CA to
provide authenticated certificate status information to
certificate users. [FPKI] Offers an alternative to issuing a CRL,
but is not supported in X.509. (See: certificate revocation tree.)
$ certificate update
(I) The act or process by which non-key data items bound in an
existing public-key certificate, especially authorizations granted
to the subject, are changed by issuing a new certificate. (See:
certificate rekey, certificate renewal.)
(C) For an X.509 public-key certificate, the essence of this
process is that fundamental changes are made in the data that is
bound to the public key, such that it is necessary to revoke the
old certificate. (Otherwise, the process is only a "certificate
rekey" or "certificate renewal".)
$ certificate user
(I) A system entity that depends on the validity of information
(such as another entity's public key value) provided by a digital
certificate. (See: relying party.)
(O) "An entity that needs to know, with certainty, the public key
of another entity." [X509]
(C) The system entity may be a human being or an organization, or
a device or process under the control of a human or an
organization.
(D) ISDs SHOULD NOT use this term as a synonym for the "subject"
of a certificate.
$ certificate validation
(I) An act or process by which a certificate user establishes that
the assertions made by a digital certificate can be trusted. (See:
valid certificate, validate vs. verify.)
(O) "The process of ensuring that a certificate is valid including
possibly the construction and processing of a certification path,
and ensuring that all certificates in that path have not expired
or been revoked." [FPDAM]
(C) To validate a certificate, a certificate user checks that the
certificate is properly formed and signed and currently in force:
- Checks the signature: Employs the issuer's public key to verify
the digital signature of the CA who issued the certificate in
question. If the verifier obtains the issuer's public key from
the issuer's own public-key certificate, that certificate
should be validated, too. That validation may lead to yet
another certificate to be validated, and so on. Thus, in
general, certificate validation involves discovering and
validating a certification path.
- Checks the syntax and semantics: Parses the certificate's
syntax and interprets its semantics, applying rules specified
for and by its data fields, such as for critical extensions in
an X.509 certificate.
- Checks currency and revocation: Verifies that the certificate
is currently in force by checking that the current date and
time are within the validity period (if that is specified in
the certificate) and that the certificate is not listed on a
CRL or otherwise announced as invalid. (CRLs themselves require
a similar validation process.)
$ certification
(I) Information system usage: Technical evaluation (usually made
in support of an accreditation action) of an information system's
security features and other safeguards to establish the extent to
which the system's design and implementation meet specified
security requirements. [FP102] (See: accreditation.)
(I) Digital certificate usage: The act or process of vouching for
the truth and accuracy of the binding between data items in a
certificate. (See: certify.)
(I) Public key usage: The act or process of vouching for the
ownership of a public key by issuing a public-key certificate that
binds the key to the name of the entity that possesses the
matching private key. In addition to binding a key to a name, a
public-key certificate may bind those items to other restrictive
or explanatory data items. (See: X.509 public-key certificate.)
(O) SET usage: "The process of ascertaining that a set of
requirements or criteria has been fulfilled and attesting to that
fact to others, usually with some written instrument. A system
that has been inspected and evaluated as fully compliant with the
SET protocol by duly authorized parties and process would be said
to have been certified compliant." [SET2]
$ certification authority (CA)
(I) An entity that issues digital certificates (especially X.509
certificates) and vouches for the binding between the data items
in a certificate.
(O) "An authority trusted by one or more users to create and
assign certificates. Optionally, the certification authority may
create the user's keys." [X509]
(C) Certificate users depend on the validity of information
provided by a certificate. Thus, a CA should be someone that
certificate users trust, and usually holds an official position
created and granted power by a government, a corporation, or some
other organization. A CA is responsible for managing the life
cycle of certificates (see: certificate management) and, depending
on the type of certificate and the CPS that applies, may be
responsible for the life cycle of key pairs associated with the
certificates (see: key management).
$ certification authority workstation (CAW)
(I) A computer system that enables a CA to issue digital
certificates and supports other certificate management functions
as required.
$ certification hierarchy
(I) A tree-structured (loop-free) topology of relationships among
CAs and the entities to whom the CAs issue public-key
certificates. (See: hierarchical PKI.)
(C) In this structure, one CA is the top CA, the highest level of
the hierarchy. (See: root, top CA.) The top CA may issue public-
key certificates to one or more additional CAs that form the
second highest level. Each of these CAs may issue certificates to
more CAs at the third highest level, and so on. The CAs at the
second-lowest of the hierarchy issue certificates only to non-CA
entities, called "end entities" that form the lowest level. (See:
end entity.) Thus, all certification paths begin at the top CA and
descend through zero or more levels of other CAs. All certificate
users base path validations on the top CA's public key.
(O) MISSI usage: A MISSI certification hierarchy has three or four
levels of CAs:
- A CA at the highest level, the top CA, is a "policy approving
authority".
- A CA at the second-highest level is a "policy creation
authority".
- A CA at the third-highest level is a local authority called a
"certification authority".
- A CA at the fourth-highest (optional) level is a "subordinate
certification authority".
(O) PEM usage: A PEM certification hierarchy has three levels of
CAs [R1422]:
- The highest level is the "Internet Policy Registration
Authority".
- A CA at the second-highest level is a "policy certification
authority".
- A CA at the third-highest level is a "certification authority".
(O) SET usage: A SET certification hierarchy has three or four
levels of CAs:
- The highest level is a "SET root CA".
- A CA at the second-highest level is a "brand certification
authority".
- A CA at the third-highest (optional) level is a "geopolitical
certification authority".
- A CA at the fourth-highest level is a "cardholder CA", a
"merchant CA", or a "payment gateway CA".
$ certification path
(I) An ordered sequence of public-key certificates (or a sequence
of public-key certificates followed by one attribute certificate)
that enables a certificate user to verify the signature on the
last certificate in the path, and thus enables the user to obtain
a certified public key (or certified attributes) of the entity
that is the subject of that last certificate. (See: certificate
validation, valid certificate.)
(O) "An ordered sequence of certificates of objects in the [X.500
Directory Information Tree] which, together with the public key of
the initial object in the path, can be processed to obtain that of
the final object in the path." [X509, R2527]
(C) The path is the "list of certificates needed to allow a
particular user to obtain the public key of another." [X509] The
list is "linked" in the sense that the digital signature of each
certificate (except the first) is verified by the public key
contained in the preceding certificate; i.e., the private key used
to sign a certificate and the public key contained in the
preceding certificate form a key pair owned by the entity that
signed.
(C) In the X.509 quotation in the previous "C" paragraph, the word
"particular" points out that a certification path that can be
validated by one certificate user might not be able to be
validated by another. That is because either the first certificate
should be a trusted certificate (it might be a root certificate)
or the signature on the first certificate should be verified by a
trusted key (it might be a root key), but such trust is defined
relative to each user, not absolutely for all users.
$ certification policy
(D) ISDs SHOULD NOT use this term. Instead, use either
"certificate policy" or "certification practice statement",
depending on what is meant.
$ certification practice statement (CPS)
(I) "A statement of the practices which a certification authority
employs in issuing certificates." [ABA96, R2527] (See: certificate
policy.)
(C) A CPS is a published security policy that can help a
certificate user to decide whether a certificate issued by a
particular CA can be trusted enough to use in a particular
application. A CPS may be (a) a declaration by a CA of the details
of the system and practices it employs in its certificate
management operations, (b) part of a contract between the CA and
an entity to whom a certificate is issued, (c) a statute or
regulation applicable to the CA, or (d) a combination of these
types involving multiple documents. [ABA]
(C) A CPS is usually more detailed and procedurally oriented than
a certificate policy. A CPS applies to a particular CA or CA
community, while a certificate policy applies across CAs or
communities. A CA with a single CPS may support multiple
certificate policies, which may be used for different application
purposes or by different user communities. Multiple CAs, each with
a different CPS, may support the same certificate policy. [R2527]
$ certification request
(I) A algorithm-independent transaction format, defined by PCKS
#10 and used in PKIX, that contains a DN, a public key, and
optionally a set of attributes, collectively signed by the entity
requesting certification, and sent to a CA, which transforms the
request to an X.509 public-key certificate or another type of
certificate.
$ certify
1. (I) Issue a digital certificate and thus vouch for the truth,
accuracy, and binding between data items in the certificate (e.g.,
see: X.509 public key certificate), such as the identity of the
certificate's subject and the ownership of a public key. (See:
certification.)
(C) To "certify a public key" means to issue a public-key
certificate that vouches for the binding between the certificate's
subject and the key.
2. (I) The act by which a CA employs measures to verify the truth,
accuracy, and binding between data items in a digital certificate.
(C) A description of the measures used for verification should be
included in the CA's CPS.
$ CFB
See: cipher feedback.
$ Challenge Handshake Authentication Protocol (CHAP)
(I) A peer entity authentication method for PPP, using a randomly-
generated challenge and requiring a matching response that depends
on a cryptographic hash of the challenge and a secret key. [R1994]
(See: challenge-response, PAP.)
$ challenge-response
(I) An authentication process that verifies an identity by
requiring correct authentication information to be provided in
response to a challenge. In a computer system, the authentication
information is usually a value that is required to be computed in
response to an unpredictable challenge value.
$ Challenge-Response Authentication Mechanism (CRAM)
(I) IMAP4 usage: A mechanism [R2195], intended for use with IMAP4
AUTHENTICATE, by which an IMAP4 client uses a keyed hash [R2104]
to authenticate itself to an IMAP4 server. (See: POP3 APOP.)
(C) The server includes a unique timestamp in its ready response
to the client. The client replies with the client's name and the
hash result of applying MD5 to a string formed from concatenating
the timestamp with a shared secret that is known only to the
client and the server.
$ channel
(I) An information transfer path within a system. (See: covert
channel.)
$ CHAP
See: Challenge Handshake Authentication Protocol.
$ checksum
(I) A value that (a) is computed by a function that is dependent
on the contents of a data object and (b) is stored or transmitted
together with the object, for the purpose of detecting changes in
the data. (See: cyclic redundancy check, data integrity service,
error detection code, hash, keyed hash, protected checksum.)
(C) To gain confidence that a data object has not been changed, an
entity that later uses the data can compute a checksum and compare
it with the checksum that was stored or transmitted with the
object.
(C) Computer systems and networks employ checksums (and other
mechanisms) to detect accidental changes in data. However, active
wiretapping that changes data could also change an accompanying
checksum to match the changed data. Thus, some checksum functions
by themselves are not good countermeasures for active attacks. To
protect against active attacks, the checksum function needs to be
well-chosen (see: cryptographic hash), and the checksum result
needs to be cryptographically protected (see: digital signature,
keyed hash).
$ chosen-ciphertext attack
(I) A cryptanalysis technique in which the analyst tries to
determine the key from knowledge of plaintext that corresponds to
ciphertext selected (i.e., dictated) by the analyst.
$ chosen-plaintext attack
(I) A cryptanalysis technique in which the analyst tries to
determine the key from knowledge of ciphertext that corresponds to
plaintext selected (i.e., dictated) by the analyst.
$ CIAC
See: Computer Incident Advisory Capability.
$ CIK
See: cryptographic ignition key.
$ cipher
(I) A cryptographic algorithm for encryption and decryption.
$ cipher block chaining (CBC)
(I) An block cipher mode that enhances electronic codebook mode by
chaining together blocks of ciphertext it produces. [FP081] (See:
[R1829], [R2451].)
(C) This mode operates by combining (exclusive OR-ing) the
algorithm's ciphertext output block with the next plaintext block
to form the next input block for the algorithm.
$ cipher feedback (CFB)
(I) An block cipher mode that enhances electronic code book mode
by chaining together the blocks of ciphertext it produces and
operating on plaintext segments of variable length less than or
equal to the block length. [FP081]
(C) This mode operates by using the previously generated
ciphertext segment as the algorithm's input (i.e., by "feeding
back" the ciphertext) to generate an output block, and then
combining (exclusive OR-ing) that output block with the next
plaintext segment (block length or less) to form the next
ciphertext segment.
$ ciphertext
(I) Data that has been transformed by encryption so that its
semantic information content (i.e., its meaning) is no longer
intelligible or directly available. (See: cleartext, plaintext.)
(O) "Data produced through the use of encipherment. The semantic
content of the resulting data is not available." [I7498 Part 2]
$ ciphertext-only attack
(I) A cryptanalysis technique in which the analyst tries to
determine the key solely from knowledge of intercepted ciphertext
(although the analyst may also know other clues, such as the
cryptographic algorithm, the language in which the plaintext was
written, the subject matter of the plaintext, and some probable
plaintext words.)
$ CIPSO
See: Common IP Security Option.
$ CKL
See: compromised key list.
$ class 2, 3, 4, or 5
(O) U.S. Department of Defense usage: Levels of PKI assurance
based on risk and value of information to be protected [DOD3]:
- Class 2: For handling low-value information (unclassified, not
mission-critical, or low monetary value) or protection of
system-high information in low- to medium-risk environment.
- Class 3: For handling medium-value information in low- to
medium-risk environment. Typically requires identification of a
system entity as a legal person, rather than merely a member of
an organization.
- Class 4: For handling medium- to high-value information in any
environment. Typically requires identification of an entity as
a legal person, rather than merely a member of an organization,
and a cryptographic hardware token for protection of keying
material.
- Class 5: For handling high-value information in a high-risk
environment.
$ classification
$ classification level
(I) (1.) A grouping of classified information to which a
hierarchical, restrictive security label is applied to increase
protection of the data. (2.) The level of protection that is
required to be applied to that information. (See: security level.)
$ classified
(I) Refers to information (stored or conveyed, in any form) that
is formally required by a security policy to be given data
confidentiality service and to be marked with a security label
(which in some cases might be implicit) to indicate its protected
status. (See: unclassified.)
(C) The term is mainly used in government, especially in the
military, although the concept underlying the term also applies
outside government. In the U.S. Department of Defense, for
example, it means information that has been determined pursuant to
Executive Order 12958 ("Classified National Security Information",
20 April 1995) or any predecessor order to require protection
against unauthorized disclosure and is marked to indicate its
classified status when in documentary form.
$ clean system
(I) A computer system in which the operating system and
application system software and files have just been freshly
installed from trusted software distribution media.
(C) A clean system is not necessarily in a secure state.
$ clearance
See: security clearance.
$ clearance level
(I) The security level of information to which a security
clearance authorizes a person to have access.
$ cleartext
(I) Data in which the semantic information content (i.e., the
meaning) is intelligible or is directly available. (See:
plaintext.)
(O) "Intelligible data, the semantic content of which is
available." [I7498 Part 2]
(D) ISDs SHOULD NOT use this term as a synonym for "plaintext",
the input to an encryption operation, because the plaintext input
to encryption may itself be ciphertext that was output from
another operation. (See: superencryption.)
$ client
(I) A system entity that requests and uses a service provided by
another system entity, called a "server". (See: server.)
(C) Usually, the requesting entity is a computer process, and it
makes the request on behalf of a human user. In some cases, the
server may itself be a client of some other server.
$ CLIPPER chip
(N) The Mykotronx, Inc. MYK-82, an integrated microcircuit with a
cryptographic processor that implements the SKIPJACK encryption
algorithm and supports key escrow. (See: CAPSTONE, Escrowed
Encryption Standard.)
(C) The key escrow scheme for a chip involves a SKIPJACK key
common to all chips that protects the unique serial number of the
chip, and a second SKIPJACK key unique to the chip that protects
all data encrypted by the chip. The second key is escrowed as
split key components held by NIST and the U.S. Treasury
Department.
$ closed security environment
(O) U.S. Department of Defense usage: A system environment that
meets both of the following conditions: (a) Application developers
(including maintainers) have sufficient clearances and
authorizations to provide an acceptable presumption that they have
not introduced malicious logic. (b) Configuration control provides
sufficient assurance that system applications and the equipment
they run on are protected against the introduction of malicious
logic prior to and during the operation of applications. [NCS04]
(See: open security environment.)
$ code
(I) noun: A system of symbols used to represent information, which
might originally have some other representation. (See: encode.)
(D) ISDs SHOULD NOT use this term as synonym for the following:
(a) "cipher", "hash", or other words that mean "a cryptographic
algorithm"; (b) "ciphertext"; or (c) "encrypt", "hash", or other
words that refer to applying a cryptographic algorithm.
(D) ISDs SHOULD NOT this word as an abbreviation for the following
terms: country code, cyclic redundancy code, Data Authentication
Code, error detection code, Message Authentication Code, object
code, or source code. To avoid misunderstanding, use the fully
qualified term, at least at the point of first usage.
$ color change
(I) In a system that is being operated in periods processing mode,
the act of purging all information from one processing period and
then changing over to the next processing period.
$ Common Criteria
$ Common Criteria for Information Technology Security
(N) "The Common Criteria" is a standard for evaluating information
technology products and systems, such as operating systems,
computer networks, distributed systems, and applications. It
states requirements for security functions and for assurance
measures. [CCIB]
(C) Canada, France, Germany, the Netherlands, the United Kingdom,
and the United States (NIST and NSA) began developing this
standard in 1993, based on the European ITSEC, the Canadian
Trusted Computer Product Evaluation Criteria (CTCPEC), and the
U.S. "Federal Criteria for Information Technology Security" (FC)
and its precursor, the TCSEC. Work was done in cooperation with
ISO/IEC Joint Technical Committee 1 (Information Technology),
Subcommittee 27 (Security Techniques), Working Group 3 (Security
Criteria). Version 2.1 of the Criteria is equivalent to ISO's
International Standard 15408 [I15408]. The U.S. Government intends
that this standard eventually will supersede both the TCSEC and
FIPS PUB 140-1. (See: NIAP.)
(C) The standard addresses data confidentiality, data integrity,
and availability and may apply to other aspects of security. It
focuses on threats to information arising from human activities,
malicious or otherwise, but may apply to non-human threats. It
applies to security measures implemented in hardware, firmware, or
software. It does not apply to (a) administrative security not
related directly to technical security, (b) technical physical
aspects of security such as electromagnetic emanation control, (c)
evaluation methodology or administrative and legal framework under
which the criteria may be applied, (d) procedures for use of
evaluation results, or (e) assessment of inherent qualities of
cryptographic algorithms.
$ Common IP Security Option (CIPSO)
See: (secondary definition under) Internet Protocol Security
Option.
$ common name
(I) A character string that (a) may be a part of the X.500 DN of a
Directory object ("commonName" attribute), (b) is a (possibly
ambiguous) name by which the object is commonly known in some
limited scope (such as an organization), and (c) conforms to the
naming conventions of the country or culture with which it is
associated. [X520] (See: ("subject" and "issuer" under) X.509
public-key certificate.)
(C) For example, "Dr. E. F. Moore", "The United Nations", or
"12-th Floor Laser Printer".
$ communication security (COMSEC)
(I) Measures that implement and assure security services in a
communication system, particularly those that provide data
confidentiality and data integrity and that authenticate
communicating entities.
(C) Usually understood to include cryptographic algorithms and key
management methods and processes, devices that implement them, and
the life cycle management of keying material and devices.
$ community string
(I) A community name in the form of an octet string that serves as
a cleartext password in SNMP version 1. [R1157]
$ compartment
(I) A grouping of sensitive information items that require special
access controls beyond those normally provided for the basic
classification level of the information. (See: category.)
(C) The term is usually understood to include the special handling
procedures to be used for the information.
$ compromise
See: data compromise, security compromise.
$ compromised key list (CKL)
(O) MISSI usage: A list that identifies keys for which
unauthorized disclosure or alteration may have occurred. (See:
compromise.)
(C) A CKL is issued by an CA, like a CRL is issued. But a CKL
lists only KMIDs, not subjects that hold the keys, and not
certificates in which the keys are bound.
$ COMPUSEC
See: computer security.
$ computer emergency response team (CERT)
(I) An organization that studies computer and network INFOSEC in
order to provide incident response services to victims of attacks,
publish alerts concerning vulnerabilities and threats, and offer
other information to help improve computer and network security.
(See: CSIRT, security incident.)
(C) For example, the CERT Coordination Center at Carnegie-Mellon
University (sometimes called "the" CERT) and the Computer Incident
Advisory Capability.
$ Computer Incident Advisory Capability (CIAC)
(N) A computer emergency response team in the U.S. Department of
Energy.
$ computer network
(I) A collection of host computers together with the subnetwork or
internetwork through which they can exchange data.
(C) This definition is intended to cover systems of all sizes and
types, ranging from the complex Internet to a simple system
composed of a personal computer dialing in as a remote terminal of
another computer.
$ computer security (COMPUSEC)
(I) Measures that implement and assure security services in a
computer system, particularly those that assure access control
service.
(C) Usually understood to include functions, features, and
technical characteristics of computer hardware and software,
especially operating systems.
$ computer security incident response team (CSIRT)
(I) An organization "that coordinates and supports the response to
security incidents that involve sites within a defined
constituency." [R2350] (See: CERT, FIRST, security incident.)
(C) To be considered a CSIRT, an organization must do as follows:
- Provide a (secure) channel for receiving reports about
suspected security incidents.
- Provide assistance to members of its constituency in handling
the incidents.
- Disseminate incident-related information to its constituency
and other involved parties.
$ computer security object
(I) The definition or representation of a resource, tool, or
mechanism used to maintain a condition of security in computerized
environments. Includes many elements referred to in standards that
are either selected or defined by separate user communities.
[CSOR] (See: object identifier, Computer Security Objects
Register.)
$ Computer Security Objects Register (CSOR)
(N) A service operated by NIST is establishing a catalog for
computer security objects to provide stable object definitions
identified by unique names. The use of this register will enable
the unambiguous specification of security parameters and
algorithms to be used in secure data exchanges.
(C) The CSOR follows registration guidelines established by the
international standards community and ANSI. Those guidelines
establish minimum responsibilities for registration authorities
and assign the top branches of an international registration
hierarchy. Under that international registration hierarchy the
CSOR is responsible for the allocation of unique identifiers under
the branch {joint-iso-ccitt(2) country(16) us(840) gov(101)
csor(3)}.
$ COMSEC
See: communication security.
$ confidentiality
See: data confidentiality.
$ configuration control
(I) The process of regulating changes to hardware, firmware,
software, and documentation throughout the development and
operational life of a system. (See: administrative security.)
(C) Configuration control helps protect against unauthorized or
malicious alteration of a system and thus provides assurance of
system integrity. (See: malicious logic.)
$ confinement property
See: (secondary definition under) Bell-LaPadula Model.
$ connectionless data integrity service
(I) A security service that provides data integrity service for an
individual IP datagram, by detecting modification of the datagram,
without regard to the ordering of the datagram in a stream of
datagrams.
(C) A connection-oriented data integrity service would be able to
detect lost or reordered datagrams within a stream of datagrams.
$ contingency plan
(I) A plan for emergency response, backup operations, and post-
disaster recovery in a system as part of a security program to
ensure availability of critical system resources and facilitate
continuity of operations in a crisis. [NCS04] (See: availability.)
$ controlled security mode
(D) ISDs SHOULD NOT use this term. It was defined in an earlier
version of the U.S. Department of Defense policy that regulates
system accreditation, but was subsumed by "partitioned security
mode" in the current version. [DOD2]
(C) The term refers to a mode of operation of an information
system, wherein at least some users with access to the system have
neither a security clearance nor a need-to-know for all classified
material contained in the system. However, separation and control
of users and classified material on the basis, respectively, of
clearance and classification level are not essentially under
operating system control like they are in "multilevel security
mode".
(C) Controlled mode was intended to encourage ingenuity in meeting
the security requirements of Defense policy in ways less
restrictive than "dedicated security mode" and "system high
security mode", but at a level of risk lower than that generally
associated with the true "multilevel security mode". This was to
be accomplished by implementation of explicit augmenting measures
to reduce or remove a substantial measure of system software
vulnerability together with specific limitation of the security
clearance levels of users permitted concurrent access to the
system.
$ cookie
(I) access control usage: A synonym for "capability" or "ticket"
in an access control system.
(I) IPsec usage: Data exchanged by ISAKMP to prevent certain
denial-of-service attacks during the establishment of a security
association.
(I) HTTP usage: Data exchanged between an HTTP server and a
browser (a client of the server) to store state information on the
client side and retrieve it later for server use.
(C) An HTTP server, when sending data to a client, may send along
a cookie, which the client retains after the HTTP connection
closes. A server can use this mechanism to maintain persistent
client-side state information for HTTP-based applications,
retrieving the state information in later connections. A cookie
may include a description of the range of URLs for which the state
is valid. Future requests made by the client in that range will
also send the current value of the cookie to the server. Cookies
can be used to generate profiles of web usage habits, and thus may
infringe on personal privacy.
$ Coordinated Universal Time (UTC)
(N) UTC is derived from International Atomic Time (TAI) by adding
a number of leap seconds. The International Bureau of Weights and
Measures computes TAI once each month by averaging data from many
laboratories. (See: GeneralizedTime, UTCTime.)
$ copy
See: card copy.
$ correctness integrity
(I) Accuracy and consistency of the information that data values
represent, rather than of the data itself. Closely related to
issues of accountability and error handling. (See: data integrity,
source integrity.)
$ correctness proof
(I) A mathematical proof of consistency between a specification
for system security and the implementation of that specification.
(See: formal specification.)
$ countermeasure
(I) An action, device, procedure, or technique that reduces a
threat, a vulnerability, or an attack by eliminating or preventing
it, by minimizing the harm it can cause, or by discovering and
reporting it so that corrective action can be taken.
(C) In an Internet protocol, a countermeasure may take the form of
a protocol feature, an element function, or a usage constraint.
$ country code
(I) An identifier that is defined for a nation by ISO. [I3166]
(C) For each nation, ISO Standard 3166 defines a unique two-
character alphabetic code, a unique three-character alphabetic
code, and a three-digit code. Among many uses of these codes, the
two-character codes are used as top-level domain names.
$ covert channel
(I) A intra-system channel that permits two cooperating entities,
without exceeding their access authorizations, to transfer
information in a way that violates the system's security policy.
(See: channel, out of band.)
(O) "A communications channel that allows two cooperating
processes to transfer information in a manner that violates the
system's security policy." [NCS04]
(C) The cooperating entities can be either two insiders or an
insider and an outsider. Of course, an outsider has no access
authorization at all. A covert channel is a system feature that
the system architects neither designed nor intended for
information transfer:
- "Timing channel": A system feature that enable one system
entity to signal information to another by modulating its own
use of a system resource in such a way as to affect system
response time observed by the second entity.
- "Storage channel": A system feature that enables one system
entity to signal information to another entity by directly or
indirectly writing a storage location that is later directly or
indirectly read by the second entity.
$ CPS
See: certification practice statement.
$ cracker
(I) Someone who tries to break the security of, and gain access
to, someone else's system without being invited to do so. (See:
hacker and intruder.)
$ CRAM
See: Challenge-Response Authentication Mechanism.
$ CRC
See: cyclic redundancy check.
$ credential(s)
(I) Data that is transferred or presented to establish either a
claimed identity or the authorizations of a system entity. (See:
authentication information, capability, ticket.)
(O) "Data that is transferred to establish the claimed identity of
an entity." [I7498 Part 2]
$ critical
1. (I) "Critical" system resource: A condition of a service or
other system resource such that denial of access to (i.e., lack of
availability of) that resource would jeopardize a system user's
ability to perform a primary function or would result in other
serious consequences. (See: availability, sensitive.)
2. (N) "Critical" extension: Each extension of an X.509
certificate (or CRL) is marked as being either critical or non-
critical. If an extension is critical and a certificate user (or
CRL user) does not recognize the extension type or does not
implement its semantics, then the user is required to treat the
certificate (or CRL) as invalid. If an extension is non-critical,
a user that does not recognize or implement that extension type is
permitted to ignore the extension and process the rest of the
certificate (or CRL).
$ CRL
See: certificate revocation list.
$ CRL distribution point
See: distribution point.
$ CRL extension
See: extension.
$ cross-certificate
See: cross-certification.
$ cross-certification
(I) The act or process by which two CAs each certify a public key
of the other, issuing a public-key certificate to that other CA.
(C) Cross-certification enables users to validate each other's
certificate when the users are certified under different
certification hierarchies.
$ cryptanalysis
(I) The mathematical science that deals with analysis of a
cryptographic system in order to gain knowledge needed to break or
circumvent the protection that the system is designed to provide.
(See: cryptology.)
(O) "The analysis of a cryptographic system and/or its inputs and
outputs to derive confidential variables and/or sensitive data
including cleartext." [I7498 Part 2]
(C) The "O" definition states the traditional goal of
cryptanalysis--convert the ciphertext to plaintext (which usually
is cleartext) without knowing the key--but that definition applies
only to encryption systems. Today, the term is used with reference
to all kinds of cryptographic algorithms and key management, and
the "I" definition reflects that. In all cases, however, a
cryptanalyst tries to uncover or reproduce someone else's
sensitive data, such as cleartext, a key, or an algorithm. The
basic cryptanalytic attacks on encryption systems are ciphertext-
only, known-plaintext, chosen-plaintext, and chosen-ciphertext;
and these generalize to the other kinds of cryptography.
$ crypto
(D) Except as part of certain long-established terms listed in
this Glossary, ISDs SHOULD NOT use this abbreviated term because
it may be misunderstood. Instead, use "cryptography" or
"cryptographic".
$ cryptographic algorithm
(I) An algorithm that employs the science of cryptography,
including encryption algorithms, cryptographic hash algorithms,
digital signature algorithms, and key agreement algorithms.
$ cryptographic application programming interface (CAPI)