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Deprecated Term: IDOCs SHOULD NOT use this term as a synonym for either of those terms; this term (a) is not as precise as they are and (b) mixes concepts in a potentially misleading way. Instead, use “identifier” or “authentication information”, depending on what is meant.

([[Fair Use]] [[Source]]: [[RFC 4949])

Identification Protocol

(I) A client-server Internet protocol [R1413] for learning the id[[entity of a user of a particular TCP connection.

Tutorial: Given a TCP port number pair, the server returns a character string that identifies the owner of that connection on the server's system. The protocol does not provide an authentication service and is not intended for authorization or access control. At best, it provides additional auditing information with respect to TCP.

([[Fair Use]] [[Source]]: [[RFC 4949])

identifier

(I) A data object – often, a printable, non-blank character string – that definitively represents a specific id[[entity of a system entity, distinguishing that id[[entity from all others. (Compare: id[[entity.)

Tutorial: Identifiers for system entities must be assigned very carefully, because authenticated identities are the basis for other security services, such as access control service.

([[Fair Use]] [[Source]]: [[RFC 4949])

identifier credential

1. (I) See: /authentication/ under “credential”.

2. (D) Synonym for “signature certificate”.

Usage: IDOCs that use this term SHOULD state a definition for it because the term is used in many ways and could easily be misunderstood.

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identifying information

(D) Synonym for “identifier”; synonym for “authentication information”. (See: authentication, identification information.)

Deprecated Term: IDOCs SHOULD NOT use this term as a synonym for either of those terms; this term (a) is not as precise as they are and (b) mixes concepts in a potentially misleading way. Instead,

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use “identifier” or “authentication information”, depending on what is meant.

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id[[entity

(I) The collective aspect of a set of attribute values (i.e., a set of characteristics) by which a system user or other system entity is recognizable or known. (See: authenticate, registration. Compare: identifier.)

Usage: An IDOC MAY apply this term to either a single entity or a set of entities. If an IDOC involves both meanings, the IDOC SHOULD use the following terms and definitions to avoid ambiguity: - “Singular id[[entity”: An id[[entity that is registered for an entity that is one person or one process. - “Shared id[[entity”: An id[[entity that is registered for an entity that is a set of singular entities (1) in which each member is authorized to assume the id[[entity individually and (2) for which the registering system maintains a record of the singular entities that comprise the set. In this case, we would expect each member entity to be registered with a singular id[[entity before becoming associated with the shared id[[entity. - “Group id[[entity”: An id[[entity that is registered for an entity (1) that is a set of entities (2) for which the registering system does not maintain a record of singular entities that comprise the set.

Tutorial: When security services are based on identities, two properties are desirable for the set of attributes used to define identities: - The set should be sufficient to distinguish each entity from all other entities, i.e., to represent each entity uniquely. - The set should be sufficient to distinguish each id[[entity from any other identities of the same entity.

The second property is needed if a system permits an entity to register two or more concurrent identities. Having two or more identities for the same entity implies that the entity has two separate justifications for registration. In that case, the set of attributes used for identities must be sufficient to represent multiple identities for a single entity.

Having two or more identities registered for the same entity is different from concurrently associating two different identifiers with the same id[[entity, and also is different from a single id[[entity concurrently accessing the system in two different roles. (See: principal, role-based access control.)

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When an id[[entity of a user is being registered in a system, the system may require presentation of evidence that proves the id[[entity's authenticity (i.e., that the user has the right to claim or use the id[[entity) and its eligibility (i.e., that the id[[entity is qualified to be registered and needs to be registered).

The following diagram illustrates how this term relates to some other terms in a PKI system: authentication information, identifier, identifier credential, registration, registered user, subscriber, and user.

Relationships: === one-to-one, =⇒ one-to-many, ⇔ many-to-many. +- - - - - - - - - - - - - - - - - - - - - - - - - - +

PKI System

+ - - - - + | +——————++————————-+ |

User,

Subscriber, i.e.,

Id[[entity of Subscriber

i.e., one

Registered User,

is system-unique

of the

is system-unique

+———————+

following

+————–+

Subscriber

User's core

Id[[entity's

+—–+

===

Registration

=⇒

Registration data

human

data, i.e.,

+——————-+

being

an entity's

same core data

+—–+

distinguishing

========

for all Identities

or

attribute

of the same User

+—–+

values

+===

+——————-+

auto-

+————–+

+———————+

mated

+——————+

+————

————+

pro-

+=======+

cess

+——-v—-

———————-

————+

+—–+

+———-v—+ +————v———-+

or

Authentication

⇐=⇒

Identifier of Id[[entity

+——-+

Information

is system-unique

a set

+————–+ +———————–+

of

Identifier Credential that associates unit of

either

Authentication Information with the Identifier

+——-+

+————————————————+

+ - - - - + + - - - - - - - - - - - - - - - - - - - - - - - - - -+

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id[[entity-based security policy

(I) “A security policy based on the identities and/or attributes of users, a group of users, or entities acting on behalf of the users and the resources/objects being accessed.” [I7498-2] (See: rule-based security policy.)

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id[[entity proofing

(I) A process that vets and verifies the information that is used to establish the id[[entity of a system entity. (See: registration.)

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IDOC

(I) An abbreviation used in this Glossary to refer to a document or other item of written material that is generated in the Internet Standards Process (RFC 2026), i.e., an RFC, an Internet- Draft, or some other item of discourse.

Deprecated Usage: This abbreviation SHOULD NOT be used in an IDOC unless it is first defined in the IDOC because the abbreviation was invented for this Glossary and is not widely known.

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IDS

(I) See: intrusion detection system.

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IEEE

(N) See: Institute of Electrical and Electronics Engineers, Inc.

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IEEE 802.10

(N) An IEEE committee developing security standards for LANs. (See: SILS.)

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IEEE P1363

(N) An IEEE working group, Standard for Public-Key Cryptography, engaged in developing a comprehensive reference standard for asymmetric cryptography. Covers discrete logarithm (e.g., DSA), elliptic curve, and integer factorization (e.g., RSA); and covers key agreement, digital signature, and encryption.

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IESG

(I) See: Internet Engineering Steering Group.

([[Fair Use]] [[Source]]: [[RFC 4949])

IETF

(I) See: Internet Engineering Task Force.

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IKE

(I) See: IPsec Key Exchange.

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IMAP4

(I) See: Internet Message Access Protocol, version 4.

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IMAP4 AUTHENTICATE

(I) An IMAP4 command (better described as a transaction type, or subprotocol) by which an IMAP4 client optionally proposes a mechanism to an IMAP4 server to authenticate the client to the server and provide other security services. (See: POP3.)

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Tutorial: If the server accepts the proposal, the command is followed by performing a challenge-response authentication protocol and, optionally, negotiating a protection mechanism for subsequent POP3 interactions. The security mechanisms that are used by IMAP4 AUTHENTICATE – including Kerberos, GSS-API, and S/Key – are described in [R1731].

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impossible

(O) Cannot be done in any reasonable amount of time. (See: break, brute force, strength, work factor.)

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in the clear

(I) Not encrypted. (See: clear text.)

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Ina Jo

(O) A methodology, language, and integrated set of software tools developed at the System Development Corporation for specifying, coding, and verifying software to produce correct and reliable programs. Usage: a.k.a. the Formal Development Methodology. [Cheh]

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incapacitation

(I) A type of threat action that prevents or interrupts system operation by disabling a system component. (See: disruption.)

Usage: This type of threat action includes the following sub types: - “Malicious logic”: In context of incapacitation, any hardware, firm ware, or software (e.g., logic bomb) intentionally introduced into a system to destroy system functions or resources. (See: corruption, main entry for “malicious logic”, masquerade, misuse.) - “Physical destruction”: Deliberate destruction of a system component to interrupt or prevent system operation. - “Human error”: /incapacitation/ Action or inaction that unintentionally disables a system component. (See: corruption, exposure.) - “Hardware or software error”: /incapacitation/ Error that unintentionally causes failure of a system component and leads to disruption of system operation. (See: corruption, exposure.) - “Natural disaster”: /incapacitation/ Any “act of God” (e.g., fire, flood, earthquake, lightning, or wind) that disables a system component. [FP031 Section 2]

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incident

See: security incident.

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INCITS

(N) See: “International Committee for Information Technology Standardization” under “ANSI”.

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indicator

(N) An action – either specific, generalized, or theoretical – that an adversary might be expected to take in preparation for an attack. [C4009] (See: “attack sensing, warning, and response”. Compare: message indicator.)

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indirect attack

(I) See: secondary definition under “attack”. Compare: direct attack.

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indirect certificate revocation list (ICRL)

(N) In X.509, a CRL that may contain certificate revocation notifications for certificates issued by CAs other than the issuer (i.e., signer) of the ICRL.

([[Fair Use]] [[Source]]: [[RFC 4949])

indistinguishability

(I) An attribute of an encryption algorithm that is a formalization of the notion that the encryption of some string is indistinguishable from the encryption of an equal-length string of nonsense. (Compare: semantic] [[security.)

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inference

1. (I) A type of threat action that reasons from characteristics or byproducts of communication and thereby indirectly accesses sensitive data, but not necessarily the data contained in the communication. (See: traffic analysis, signal analysis.)

2. (I) A type of threat action that indirectly gains unauthorized access to sensitive information in a database management system by correlating query responses with information that is already known.

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inference control

(I) Protection of data confidentiality against inference attack. (See: traffic-flow confidentiality.)

Tutorial: A database management system containing N records about individuals may be required to provide statistical summaries about subsets of the population, while not revealing sensitive information about a single individual. An attacker may try to obtain sensitive information about an individual by isolating a desired record at the intersection of a set of overlapping queries. A system can attempt to prevent this by restricting the size and overlap of query sets, distorting responses by rounding or otherwise perturbing database values, and limiting queries to random samples. However, these techniques may be impractical to implement or use, and no technique is totally effective. For example, restricting the minimum size of a query set – that is,

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not responding to queries for which there are fewer than K or more than N-K records that satisfy the query – usually cannot prevent unauthorized disclosure. An attacker can pad small query sets with extra records, and then remove the effect of the extra records. The formula for identifying the extra records is called the “tracker”. [Denns]

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INFOCON

(O) See: information operations condition

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informal

(N) Expressed in natural language. [CCIB] (Compare: formal, semiformal.)

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information

1. (I) Facts and ideas, which can be represented (encoded) as various forms of data.

2. (I) Knowledge – e.g., data, instructions – in any medium or form that can be communicated between system entities.

Tutorial: Internet security could be defined simply as protecting information in the Internet. However, the perceived need to use different protective measures for different types of information (e.g., authentication information, classified information, collateral information, national security information, personal information, protocol control information, sensitive compartmented information, sensitive information) has led to the diversity of terminology listed in this Glossary.

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information assurance

(N) /U.S. Government/ “Measures that protect and defend information and information systems by ensuring their availability integrity, authentication, confidentiality, and non-repudiation. These measures include providing for restoration of information systems by incorporating protection, detection, and reaction capabilities.” [C4009]

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Information Assurance Technical Framework (IATF)

(O) A publicly available document [IATF], developed through a collaborative effort by organizations in the U.S. Government and industry, and issued by NSA. Intended for security managers and system security engineers as a tutorial and reference document about security problems in information systems and networks, to improve awareness of tradeoffs among available technology solutions and of desired characteristics of security approaches for particular problems. (See: ISO 17799, [SP14].)

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information domain

(O) See: secondary definition under “domain”.

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information domain security policy

(O) See: secondary definition under “domain”.

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information flow policy

(N) /formal model/ A triple consisting of a set of security levels (or their equivalent security labels), a binary operator that maps each pair of security levels into a security level, and a binary relation on the set that selects a set of pairs of levels such that information is permitted to flow from an object of the first level to an object of the second level. (See: flow control, lattice model.)

([[Fair Use]] [[Source]]: [[RFC 4949])

information operations condition (INFOCON)

(O) /U.S. DoD/ A comprehensive defense posture and response based on the status of information systems, military operations, and intelligence assessments of adversary capabilities and intent. (See: threat)

Derivation: From DEFCON, i.e., defense condition.

Tutorial: The U.S. DoD defines five INFOCON levels: NORMAL (normal activity), ALPHA (increased risk of attack), BRAVO (specific risk of attack), CHARLIE (limited attack), and DELTA (general attack).

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information security (INFOSEC)

(N) Measures that implement and assure security services in information systems, including in computer systems (see: COMPUSEC) and in communication systems (see: COMSEC).

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information system

(I) An organized assembly of computing and communication resources and procedures – i.e., equipment and services, together with their supporting infrastructure, facilities, and personnel – that create, collect, record, process, store, transport, retrieve, display, disseminate, control, or dispose of information to accomplish a specified set of functions. (See: system entity, system resource. Compare: computer platform.)

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Information Technology Security Evaluation Criteria (ITSEC)

(N) A Standard [ITSEC] jointly developed by France, Germany, the Netherlands, and the United Kingdom for use in the European Union; accommodates a wider range of security assurance and functionality combinations than the TCSEC. Superseded by the Common Criteria.

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INFOSEC

(I) See: information security.

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ingress filtering

(I) A method [R2827] for countering attacks that use packets with false IP source addresses, by blocking such packets at the boundary between connected networks.

Tutorial: Suppose network A of an internet service provider (ISP) includes a filtering router that is connected to customer network B, and an attacker in B at IP source address “foo” attempts to send packets with false source address “bar” into A. The false address may be either fixed or randomly changing, and it may either be unreachable or be a forged address that legitimately exists within either B or some other network C. In ingress filtering, the ISP's router blocks all inbound packet that arrive from B with a source address that is not within the range of legitimately advertised addresses for B. This method does not prevent all attacks that can originate from B, but the actual source of such attacks can be more easily traced because the originating network is known.

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initialization value (IV)

(I) /cryptography/ An input parameter that sets the starting state of a cryptographic algorithm or mode. (Compare: activation data.)

Tutorial: An IV can be used to synchronize one cryptographic process with another; e.g., CBC, CFB, and OFB use IVs. An IV also can be used to introduce cryptographic variance (see: salt) besides that provided by a key.

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initialization vector

(D) /cryptography/ Synonym for “initialization value”.

Deprecated Term: To avoid international misunderstanding, IDOCs SHOULD NOT use this term in the context of cryptography because most dictionary definitions of “vector” includes a concept of direction or magnitude, which are irrelevant to cryptographic use.

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insertion

1. (I) /packet/ See: secondary definition under “stream integrity service”.

2. (I) /threat action/ See: secondary definition under “falsification”.

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inside attack

(I) See: secondary definition under “attack”. Compare: insider.

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insider

1. (I) A user (usually a person) that accesses a system from a position that is inside the system's security perimeter. (Compare: authorized user, outsider, unauthorized user.)

Tutorial: An insider has been assigned a role that has more privileges to access system resources than do some other types of users, or can access those resources without being constrained by some access controls that are applied to outside users. For example, a salesclerk is an insider who has access to the cash register, but a store customer is an outsider.

The actions performed by an insider in accessing the system may be either authorized or unauthorized; i.e., an insider may act either as an authorized user or as an unauthorized user.

2. (O) A person with authorized physical access to the system. Example: In this sense, an office janitor is an insider, but a burglar or casual visitor is not. [NRC98]

3. (O) A person with an organizational status that causes the system or members of the organization to view access requests as being authorized. Example: In this sense, a purchasing agent is an insider but a vendor is not. [NRC98]

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inspectable space

(O) /EMSEC/ “Three-dimensional space surrounding equipment that process classified and/or sensitive information within which TEMPEST exploitation is not considered practical or where legal authority to identify and/or remove a potential TEMPEST exploitation exists.” [C4009] (Compare: control zone, TEMPEST zone.)

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Institute of Electrical and Electronics Engineers, Inc. (IEEE)

(N) The IEEE is a not-for-profit association of approximately 300,000 individual members in 150 countries. The IEEE produces nearly one third of the world's published literature in electrical engineering, computers, and control technology; holds hundreds of major, annual conferences; and maintains more than 800 active standards, with many more under development. (See: SILS.)

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integrity

See: data integrity, datagram integrity service, correctness integrity, source integrity, stream integrity service, system integrity.

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integrity check

(D) A computation that is part of a mechanism to provide data integrity service or data origin authentication service. (Compare: checksum.)

Deprecated Term: IDOCs SHOULD NOT use this term as a synonym for “cryptographic hash” or “protected checksum”. This term unnecessarily duplicates the meaning of other, well-established terms; this term only mentions integrity, even though the intended service may be data origin authentication; and not every checksum is crypto graphically protected.

([[Fair Use]] [[Source]]: [[RFC 4949])

integrity label

(I) A security label that tells the degree of confidence that may be placed in the data, and may also tell what counter measures are required to be applied to protect the data from alteration and destruction. (See: integrity. Compare: classification label.)

([[Fair Use]] [[Source]]: [[RFC 4949])

intelligent threat

(I) A circumstance in which an adversary has the technical and operational ability to detect and exploit a vulnerability and also has the demonstrated, presumed, or inferred intent to do so. (See: threat.)

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interception

(I) A type of threat action whereby an unauthorized entity directly accesses sensitive data while the data is traveling between authorized sources and destinations. (See: unauthorized disclosure.)

Usage: This type of threat action includes the following sub types: - “Theft”: Gaining access to sensitive data by stealing a shipment of a physical medium, such as a magnetic tape or disk, that holds the data. - “Wire tapping (passive)”: Monitoring and recording data that is flowing between two points in a communication system. (See: wire tapping.) - “Emanations analysis”: Gaining direct knowledge of communicated data by monitoring and resolving a signal that is emitted by a system and that contains the data but was not intended to communicate the data. (See: emanation.)

([[Fair Use]] [[Source]]: [[RFC 4949])

interference

(I) /threat action/ See: secondary definition under “obstruction”.

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intermediate CA

(D) The CA that issues a cross-certificate to another CA. [X509] (See: cross-certification.)

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Deprecated Term: IDOCs SHOULD NOT use this term because it is not widely known and mixes concepts in a potentially misleading way. For example, suppose that end entity 1 (“EE1) is in one PKI (“PKI1”), end entity 2 (“EE2) is in another PKI (“PKI2”), and the root in PKI1 (“CA1”) cross-certifies the root CA in PKI2 (“CA2”). Then, if EE1 constructs the certification path CA1-to-CA2-to-EE2 to validate a certificate of EE2, conventional English usage would describe CA2 as being in the ”intermediate” position in that path, not CA1.

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internal controls

(I) /COMPUSEC/ Functions, features, and technical characteristics of computer hardware and software, especially of operating systems. Includes mechanisms to regulate the operation of a computer system with regard to access control, flow control, and inference control. (Compare: external controls.)

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International Data Encryption Algorithm (IDEA)

(N) A patented, symmetric block cipher that uses a 128-bit key and operates on 64-bit blocks. [Schn] (See: symmetric cryptography.)

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International Standard

(N) See: secondary definition under “ISO”.

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International Traffic in Arms Regulations (ITAR)

(O) Rules issued by the U.S. State Department, by authority of the Arms Export Control Act (22 U.S.C. 2778), to control export and import of defense articles and defense services, including information security systems, such as cryptographic systems, and TEMPEST suppression technology. (See: type 1 product, Wassenaar Arrangement.)

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internet, Internet

1. (I) /not capitalized/ Abbreviation of “internet work”.

2. (I) /capitalized/ The Internet is the single, interconnected, world wide system of commercial, govern mental, educational, and other computer networks that share (a) the protocol suite specified by the IAB (RFC 2026) and (b) the name and address spaces managed by the ICANN. (See: Internet Layer, Internet Protocol Suite.)

Usage: Use with definite article (“the”) when using as a noun. For example, say “My LAN is small, but the Internet is large.” Don't say “My LAN is small, but Internet is large.”

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Internet Architecture Board (IAB)

(I) A technical advisory group of the ISOC, chartered by the ISOC Trustees to provide oversight of Internet architecture and protocols and, in the context of Internet Standards, a body to which decisions of the IESG may be appealed. Responsible for approving appointments to the IESG from among nominees submitted by the IETF nominating committee. (RFC 2026)

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Internet Assigned Numbers Authority (IANA)

(I) From the early days of the Internet, the IANA was chartered by the ISOC and the U.S. Government's Federal Network Council to be the central coordination, allocation, and registration body for parameters for Internet protocols. Superseded by ICANN.

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Internet Control Message Protocol (ICMP)

(I) An Internet Standard protocol (RFC 792) that is used to report error conditions during IP datagram processing and to exchange other information concerning the state of the IP network.

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Internet Corporation for Assigned Names and Numbers (ICANN)

(I) The non-profit, private corporation that has assumed responsibility for the IP address space allocation, protocol parameter assignment, DNS management, and root server system management functions formerly performed under U.S. Government contract by IANA and other entities.

Tutorial: The IPS, as defined by the IETF and the IESG, contains numerous parameters, such as Internet addresses, domain names, autonomous system numbers, protocol numbers, port numbers, management information base OIDs, including private enterprise numbers, and many others. The Internet community requires that the values used in these parameter fields be assigned uniquely. ICANN makes those assignments as requested and maintains a registry of the current values.

ICANN was formed in October 1998, by a coalition of the Internet's business, technical, and academic communities. The U.S. Government designated ICANN to serve as the global consensus entity with responsibility for coordinating four key functions for the Internet: allocation of IP address space, assignment of protocol parameters, management of the DNS, and management of the DNS root server system.

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Internet-Draft

(I) A working document of the IETF, its areas, and its working groups. (RFC 2026) (Compare: RFC.)

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Usage: The term is customarily hyphenated when used either as a adjective or a noun, even though the latter is not standard English punctuation.

Tutorial: An Internet-Draft is not an archival document like an RFC is. Instead, an Internet-Draft is a preliminary or working document that is valid for a maximum of six months and may be updated, replaced, or made obsolete by other documents at any time. It is inappropriate to use an Internet-Draft as reference material or to cite it other than as a “work in progress”. Although most of the Internet-Drafts are produced by the IETF, any interested organization may request to have its working documents published as Internet-Drafts.

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Internet Engineering Steering Group (IESG)

(I) The part of the ISOC responsible for technical management of IETF activities and administration of the Internet Standards Process according to procedures approved by the ISOC Trustees. Directly responsible for actions along the “standards track”, including final approval of specifications as Internet Standards. Composed of IETF Area Directors and the IETF chairperson, who also chairs the IESG. (RFC 2026)

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Internet Engineering Task Force (IETF)

(I) A self-organized group of people who make contributions to the development of Internet technology. The principal body engaged in developing Internet Standards, although not itself a part of the ISOC. Composed of Working Groups, which are arranged into Areas (such as the Security Area), each coordinated by one or more Area Directors. Nominations to the IAB and the IESG are made by a committee selected at random from regular IETF meeting attendees who have volunteered. (RFCs 2026, 3935) [R2323]

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Internet Key Exchange (IKE)

(I) An Internet, IPsec, key-establishment protocol [R4306] for putting in place authenticated keying material (a) for use with ISAKMP and (b) for other security associations, such as in AH and ESP.

Tutorial: IKE is based on three earlier protocol designs: ISAKMP, OAKLEY, and SKEME.

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Internet Layer

(I) See: Internet Protocol Suite.

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Internet Message Access Protocol, version 4 (IMAP4)

(I) An Internet protocol (RFC 2060) by which a client workstation can dynamically access a mail box on a server host to manipulate

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and retrieve mail messages that the server has received and is holding for the client. (See: POP3.)

Tutorial: IMAP4 has mechanisms for optionally authenticating a client to a server and providing other security services. (See: IMAP4 AUTHENTICATE.)

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Internet Open Trading Protocol (IOTP)

(I) An Internet protocol [R2801] proposed as a general framework for Internet commerce, able to encapsulate transactions of various proprietary payment systems (e.g., GeldKarte, Mondex, SET, Visa Cash). Provides optional security services by incorporating various Internet security mechanisms (e.g., MD5) and protocols (e.g., TLS).

([[Fair Use]] [[Source]]: [[RFC 4949])

Internet Policy Registration Authority (IPRA)

(I) An X.509-compliant CA that is the top CA of the Internet certification hierarchy operated under the auspices of the ISOC [R1422]. (See: /PEM/ under “certification hierarchy”.)

([[Fair Use]] [[Source]]: [[RFC 4949])

Internet Private Line Interface (IPLI)

(O) A successor to the PLI, updated to use TCP/IP and newer military-grade COMSEC equipment (TSEC/KG-84). The IPLI was a portable, modular system that was developed for use in tactical, packet-radio networks. (See: end-to-end encryption.)

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Internet Protocol (IP)

(I) An Internet Standard, Internet-Layer protocol that moves datagrams (discrete sets of bits) from one computer to another across an internet work but does not provide reliable delivery, flow control, sequencing, or other end-to-end services that TCP provides. IP version 4 (IPv4) is specified in RFC 791, and IP version 6 (IPv6) is specified in RFC 2460. (See: IP address, TCP/IP.)

Tutorial: If IP were used in an OSIRM stack, IP would be placed at the top of Layer 3, above other Layer 3 protocols in the stack.

In any IPS stack, IP is always present in the Internet Layer and is always placed at the top of that layer, on top of any other protocols that are used in that layer. In some sense, IP is the only protocol specified for the IPS Internet Layer; other protocols used there, such as AH and ESP, are just IP variations.

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Internet Protocol security

See: IP Security Protocol.

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Internet Protocol Security Option (IPSO)

(I) Refers to one of three types of IP security options, which are fields that may be added to an IP datagram for carrying security information about the datagram. (Compare: IPsec.)

Deprecated Usage: IDOCs SHOULD NOT use this term without a modifier to indicate which of the following three types is meant: - “DoD Basic Security Option” (IP option type 130): Defined for use on U.S. DoD common-use data networks. Identifies the DoD classification level at which the datagram is to be protected and the protection authorities whose rules apply to the datagram. (A “protection authority” is a National Access Program (e.g., GENSER, SIOP-ESI, SCI, NSA, Department of Energy) or Special Access Program that specifies protection rules for transmission and processing of the information contained in the datagram.) [R1108] - “DoD Extended Security Option” (IP option type 133): Permits additional security labeling information, beyond that present in the Basic Security Option, to be supplied in the datagram to meet the needs of registered authorities. [R1108] - “Common IP Security Option” (CIPSO) (IP option type 134): Designed by TSIG to carry hierarchic and non-hierarchic security labels. (Formerly called “Commercial IP Security Option”; a version 2.3 draft was published 9 March 1993 as an Internet-Draft but did not advance to RFC form.) [CIPSO]

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Internet Protocol Suite (IPS)

(I) The set of network communication protocols that are specified by the IETF, and approved as Internet Standards by the IESG, within the oversight of the IAB. (See: OSIRM Security Architecture. Compare: OSIRM.)

Usage: This set of protocols is popularly known as “TCP/IP” because TCP and IP are its most basic and important components.

For clarity, this Glossary refers to IPS protocol layers by name and capitalizes those names, and refers to OSIRM protocol layers by number.

Tutorial: The IPS does have architectural principles [R1958], but there is no Internet Standard that defines a layered IPS reference model like the OSIRM. Still, Internet community literature has referred (inconsistently) to IPS layers since early in the Internet's development [Padl].

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This Glossary treats the IPS as having five protocol layers – Application, Transport, Internet, Network Interface, and Network Hardware (or Network Substrate) – which are illustrated in the following diagram:

OSIRM Layers Examples IPS Layers Examples —————— ————— ————— ————– Message Format: P2[X420]Message Format: ARPA (RFC 822) +—————-++————-+

7.Application

P1[X419]

Application

+—————-+ - - - - - - | |

6.Presentation

[I8823]

+—————-+ - - - - - - | |

5.Session

+—————-+ - - - - - - | Transport | TCP (RFC 793)

4.Transport

TP4 [I8073]

+—————-+ - - - - - - +————-+

3.Network	CLNP [I8473]	Internet

		Network

+—————-+ - - - - - - | Interface | 802 (RFC 1042)

2.Data Link

+—————-+- (or Network - standards for

1.Physical

+—————-+ Signaling [Stal] + - - - - - - +

The diagram approximates how the five IPS layers align with the seven OSIRM layers, and it offers examples of protocol stacks that provide roughly equivalent electronic mail service over a private LAN that uses base band signaling.

- IPS Application Layer: The user runs an application program. The program selects the data transport service it needs – either a sequence of data messages or a continuous stream of data – and hands application data to the Transport Layer for delivery.

- IPS Transport Layer: This layer divides application data into packets, adds a destination address to each, and communicates them end-to-end – from one application program to another – optionally regulating the flow and ensuring reliable (error- free and sequenced) delivery.

- IPS Internet Layer: This layer carries transport packets in IP datagrams. It moves each datagram independently, from its source computer to its addressed destination computer, routing

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the datagram through a sequence of networks and relays and selecting appropriate network interfaces en route.

- IPS Network Interface Layer: This layer accepts datagrams for transmission over a specific network. This layer specifies interface conventions for carrying IP over OSIRM Layer 3 protocols and over Media Access Control sub layer protocols of OSIRM Layer 2. An example is IP over IEEE 802 (RFD 1042).

- IPS Network Hardware Layer: This layer consists of specific, physical communication media. However, the IPS does not specify its own peer-to-peer protocols in this layer. Instead, the layering conventions specified by the Network Interface Layer use Layer 2 and Layer 3 protocols that are specified by bodies other than the IETF. That is, the IPS addresses *inter*-network functions and does not address

intra*-network functions.

The two models are most dissimilar in the upper layers, where the IPS model does not include Session and Presentation layers. However, this omission causes fewer functional differences between the models than might be imagined, and the differences have relatively few security implications:

- Formal separation of OSIRM Layers 5, 6, and 7 is not needed in implementations; the functions of these layers sometimes are mixed in a single software unit, even in protocols in the OSI suite.

- Some OSIRM Layer 5 services – for example, connection termination – are built into TCP, and the remaining Layer 5 and 6 functions are built into IPS Application-Layer protocols where needed.

- The OSIRM does not place any security services in Layer 5 (see: OSIRM Security Architecture).

- The lack of an explicit Presentation Layer in the IPS sometimes makes it simpler to implement security in IPS applications. For example, a primary function of Layer 6 is to convert data between internal and external forms, using a transfer syntax to unambiguously encode data for transmission. If an OSIRM application encrypts data to protect against disclosure during transmission, the transfer encoding must be done before the encryption. If an application does encryption, as is done in OSI message handling and directory service protocols, then Layer 6 functions must be replicated in Layer 7. X400, X500].

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The two models are most alike at the top of OSIRM Layer 3, where the OSI Connectionless Network Layer Protocol (CLNP) and the IPS IP are quite similar. Connection-oriented security services offered in OSIRM Layer 3 are inapplicable in the IPS, because the IPS Internet Layer lacks the explicit, connection-oriented service offered in the OSIRM.

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Internet Security Association and Key Management Protocol (ISAKMP)

(I) An Internet IPsec protocol [R2408] to negotiate, establish, modify, and delete security associations, and to exchange key generation and authentication data, independent of the details of any specific key generation technique, key establishment protocol, encryption algorithm, or authentication mechanism.

Tutorial: ISAKMP supports negotiation of security associations for protocols at all IPS layers. By centralizing management of security associations, ISAKMP reduces duplicated functionality within each protocol. ISAKMP can also reduce connection setup time, by negotiating a whole stack of services at once. Strong authentication is required on ISAKMP exchanges, and a digital signature algorithm based on asymmetric cryptography is used within ISAKMP's authentication component.

ISAKMP negotiations are conducted in two “phases”: - “Phase 1 negotiation”. A phase 1 negotiation establishes a security association to be used by ISAKMP to protect its own protocol operations. - “Phase 2 negotiation”. A phase 2 negotiation (which is protected by a security association that was established by a phase 1 negotiation) establishes a security association to be used to protect the operations of a protocol other than ISAKMP, such as ESP.

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Internet Society (ISOC)

(I) A professional society concerned with Internet development (including technical Internet Standards); with how the Internet is and can be used; and with social, political, and technical issues that result. The ISOC Board of Trustees approves appointments to the IAB from among nominees submitted by the IETF nominating committee. (RFC 2026)

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Internet Standard

(I) A specification, approved by the IESG and published as an RFC, that is stable and well-understood, is technically competent, has multiple, independent, and interoperable implementations with substantial operational experience, enjoys significant public support, and is recognizably useful in some or all parts of the Internet. (RFC 2026) (Compare: RFC.)

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Tutorial: The “Internet Standards Process” is an activity of the ISOC and is organized and managed by the IAB and the IESG. The process is concerned with all protocols, procedures, and conventions used in or by the Internet, whether or not they are part of the IPS. The “Internet Standards Track” has three levels of increasing maturity: Proposed Standard, Draft Standard, and Standard. (Compare: ISO, W3C.)

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internet work

(I) A system of interconnected networks; a network of networks. Usually shortened to “internet”. (See: internet, Internet.)

Tutorial: An internet can be built using OSIRM Layer 3 gateways to implement connections between a set of similar subnet works. With dissimilar subnet works, i.e., subnet works that differ in the Layer 3 protocol service they offer, an internet can be built by implementing a uniform internet work protocol (e.g., IP) that operates at the top of Layer 3 and hides the underlying subnet works' heterogeneity from hosts that use communication services provided by the internet. (See: router.)

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intranet

(I) A computer network, especially one based on Internet technology, that an organization uses for its own internal (and usually private) purposes and that is closed to outsiders. (See: extranet, VPN.)

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intruder

(I) An entity that gains or attempts to gain access to a system or system resource without having authorization to do so. (See: intrusion. Compare: adversary, cracker, hacker.)

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intrusion

1. (I) A security event, or a combination of multiple security events, that constitutes a security incident in which an intruder gains, or attempts to gain, access to a system or system resource without having authorization to do so. (See: IDS.)

2. (I) A type of threat action whereby an unauthorized entity gains access to sensitive data by circumventing a system's security protections. (See: unauthorized disclosure.)

Usage: This type of threat action includes the following sub types: - “Trespass”: Gaining physical access to sensitive data by circumventing a system's protections. - “Penetration”: Gaining logical access to sensitive data by circumventing a system's protections.

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- “Reverse engineering”: Acquiring sensitive data by disassembling and analyzing the design of a system component. - “Crypt analysis”: Transforming encrypted data into plain text without having prior knowledge of encryption parameters or processes. (See: main entry for “crypt analysis”.)

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intrusion detection

(I) Sensing and analyzing system events for the purpose of noticing (i.e., becoming aware of) attempts to access system resources in an unauthorized manner. (See: anomaly detection, IDS, misuse detection. Compare: extrusion detection.) [IDSAN, IDSSC, IDSSE, IDSSY]

Usage: This includes the following sub types: - “Active detection”: Real-time or near-real-time analysis of system event data to detect current intrusions, which result in an immediate protective response. - “Passive detection”: Off-line analysis of audit data to detect past intrusions, which are reported to the system security officer for corrective action. (Compare: security audit.)

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intrusion detection system (IDS)

1. (N) A process or sub system, implemented in software or hardware, that automates the tasks of (a) monitoring events that occur in a computer network and (b) analyzing them for signs of security problems. [SP31] (See: intrusion detection.)

2. (N) A security alarm system to detect unauthorized entry. [DC6/9].

Tutorial: Active intrusion detection processes can be either host- based or network-based: - “Host-based”: Intrusion detection components – traffic sensors and analyzers – run directly on the hosts that they are intended to protect. - “Network-based”: Sensors are placed on subnet work components, and analysis components run either on subnet work components or hosts.

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invalidity date

(N) An X.509 CRL entry extension that “indicates the date at which it is known or suspected that the [revoked certificate's private key was compromised or that the certificate should otherwise be considered invalid.” [X509].

Tutorial: This date may be earlier than the revocation date in the CRL entry, and may even be earlier than the date of issue of earlier CRLs. However, the invalidity date is not, by itself,

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sufficient for purposes of non-repudiation service. For example, to fraudulently repudiate a validly generated signature, a private key holder may falsely claim that the key was compromised at some time in the past.

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IOTP

(I) See: Internet Open Trading Protocol.

([[Fair Use]] [[Source]]: [[RFC 4949])

IP

(I) See: Internet Protocol.

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IP address

(I) A computer's internet work address that is assigned for use by IP and other protocols.

Tutorial: An IP version 4 address (RFC 791) has four 8-bit parts and is written as a series of four decimal numbers separated by periods. Example: The address of the host named “rosslyn.bbn.com” is 192.1.7.10.

An IP version 6 address (RFC 2373) has eight 16-bit parts and is written as eight hexadecimal numbers separated by colons. Examples: 1080:0:0:0:8:800:200C:417A and FEDC:BA98:7654:3210:FEDC:BA98:7654:3210.

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IP Security Option

(I) See: Internet Protocol Security Option.

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IP Security Protocol (IPsec)

1a. (I) The name of the IETF working group that is specifying an architecture [R2401, R4301] and set of protocols to provide security services for IP traffic. (See: AH, ESP, IKE, SAD, SPD. Compare: IPSO.)

1b. (I) A collective name for the IP security architecture [R4301] and associated set of protocols (primarily AH, ESP, and IKE).

Usage: In IDOCs that use the abbreviation “IPsec”, the letters “IP” SHOULD be in upper case, and the letters “sec” SHOULD NOT.

Tutorial: The security services provided by IPsec include access control service, connectionless data integrity service, data origin authentication service, protection against replays (detection of the arrival of duplicate datagrams, within a constrained window), data confidentiality service, and limited traffic-flow confidentiality. IPsec specifies (a) security protocols (AH and ESP), (b) security associations (what they are, how they work, how they are managed, and associated processing),

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IPLI

(I) See: Internet Private Line Interface.

([[Fair Use]] [[Source]]: [[RFC 4949])

IPRA

(I) See: Internet Policy Registration Authority.

([[Fair Use]] [[Source]]: [[RFC 4949])

IPS

(I) See: Internet Protocol Suite.

([[Fair Use]] [[Source]]: [[RFC 4949])

IPsec

(I) See: IP Security Protocol.

([[Fair Use]] [[Source]]: [[RFC 4949])

IPSO

(I) See: Internet Protocol Security Option.

([[Fair Use]] [[Source]]: [[RFC 4949])

ISAKMP

(I) See: Internet Security Association and Key Management Protocol.

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ISO

(I) International Organization for Standardization, a voluntary, non-treaty, non-govern mental organization, established in 1947, with voting members that are designated standards bodies of participating nations and non-voting observer organizations. (Compare: ANSI, IETF, ITU-T, W3C.)

Tutorial: Legally, ISO is a Swiss, non-profit, private organization. ISO and the IEC (the International Electrotechnical Commission) form the specialized system for world wide standardization. National bodies that are members of ISO or IEC participate in developing international standards through ISO and IEC technical committees that deal with particular fields of activity. Other international govern mental and non-govern mental organizations, in liaison with ISO and IEC, also take part. (ANSI is the U.S. voting member of ISO. ISO is a class D member of ITU- T.)

The ISO standards development process has four levels of increasing maturity: Working Draft (WD), Committee Draft (CD), Draft International Standard (DIS), and International Standard (IS). (Compare: “Internet Standards Track” under “Internet Standard”.) In information technology, ISO and IEC have a joint technical committee, ISO/IEC JTC 1. DISs adopted by JTC 1 are

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circulated to national bodies for voting, and publication as an IS requires approval by at least 75% of the national bodies casting a vote.

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ISO 17799

(N) An International Standard that is a code of practice, derived from Part 1 of British Standard 7799, for managing the security of information systems in an organization. This standard does not provide definitive or specific material on any security v. It provides general guidance on a wide variety of vs, but typically does not go into depth. (See: IATF, [SP14].)

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ISOC

(I) See: Internet Society.

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issue

(I) /PKI/ Generate and sign a digital certificate (or a CRL) and, usually, distribute it and make it available to potential certificate users (or CRL users). (See: certificate creation.)

Usage: The term “issuing” is usually understood to refer not only to creating a digital certificate (or a CRL) but also to making it available to potential users, such as by storing it in a repository or other directory or otherwise publishing it. However, the ABA [DSG] explicitly limits this term to the creation process and excludes any related publishing or distribution process.

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issuer

1. (I) /certificate, CRL/ The CA that signs a digital certificate or CRL.

Tutorial: An X.509 certificate always includes the issuer's name. The name may include a common name value.

2. (O) /payment card, SET/ “The financial institution or its agent that issues the unique primary account number to the cardholder for the payment card brand.” [SET2]

Tutorial: The institution that establishes the account for a cardholder and issues the payment card also guarantees payment for authorized transactions that use the card in accordance with card brand regulations and local legislation. [SET1]