Certification AgentThe individual, group, or organization responsible for conducting a security certification.
certification authority (CA)In cryptography, a center trusted by one or more agencies or individuals to create and assign certificates and, optionally, to create user's keys.
certification pathIn cryptography, the ordered sequence of entity certificates that can be processed, with the public key of the initial entity in the path, to determine…
certified identityAn identity in the form of an attribute in a certificate. The issuing authority will have authenticated the owner of the certificate [ECMA138].
certified network engineerIn computer networking, one who has met proprietary training and certification requirements pertinent to network design or maintenance.
CertifierPerson responsible for certification of a system and/or product [CESG]
cesium clockA clock containing a cesium standard as a frequency-determining element.
cesium standardA primary frequency standard in which electronic transitions between the two hyperfine ground states of cesium-133 atoms control the output frequency.
CGIAbbreviation for common gateway interface. A means for allowing programs or scripts (usually written in C++ or Perl) to add functionality to the World…
cgmAbbreviation for computer graphics metafile. A digital file format (standard) used for the storage or transmission of digital representations of graphics…
challenge and reply authentication[A] prearranged procedure in which a subject requests authentication of another, and the latter establishes validity with a correct reply. [INFOSEC-99]
change backThe procedure of transferring signaling traffic from alternative signaling link(s) to the signaling link which has become available as a result of having…
changeoverThe procedure of transferring signaling traffic from one signaling link to one or more different signaling links, when the link in use fails or is…
ChannelThe bed of a stream or river. This can also refer to a submerged stream or river channel in a reservoir.
channel bankThe part of a carrier-multiplex terminal that performs the first step of modulation by multiplexing a group of channels into a higher bandwidth analog…
channel bitsBinary data transmitted over a communications link. Note: Channel bits are derived from user information by FEC (forward error correction) coding and…
channel capacity1. The maximum possible information transfer rate through a channel, subject to specified constraints. 2.
channel gateA device for connecting a channel to a highway, or a highway to a channel, at specified times.
channel noise levelThe ratio of the channel noise at any point in a transmission system to an arbitrary level chosen as a reference.
channel offsetThe constant frequency difference between a channel frequency and a reference frequency which may frequency hop.
channel packingMaximizing the use of voice frequency channels for data transmission by multiplexing a number of channels of lower data rate into a single voice frequency…
channel reliability (ChR)The percentage of time a channel was available for use in a specified period of scheduled availability.
channel service unit (CSU)A line bridging device that (a) is used to perform loop-back testing, (b) may perform bit stuffing, (c) may also provide a framing and formatting pattern…
channel time slotA time slot that starts at a particular instant in a frame and is allocated to a channel for transmitting data, such as a character or an in-slot signal.
channel-associated signalingSignaling in which the signals necessary to switch a given circuit are transmitted via the circuit itself or via a signaling channel permanently…
channelingAn application of push technology that allows users to automatically receive specific kinds of content. [Bahorsky]
ChannelizationThe modification of a natural river channel; may include deepening, widening, or straightening.
character checkA method of error detection using the preset rules for the formulation of characters.
character filterSoftware that is capable of selectively removing characters from a data stream, e.g.
character generatorA functional unit that converts the coded representation of a character into the graphic representation of the character for display.
character integrityPreservation of a character during processing, storage, and transmission.
character intervalIn a communications system, the total number of unit intervals required to transmit any given character, including synchronizing, information, error…
character setA grouping of alphabetic, numeric, and other characters that have some relationship in common.
character-count integrityThe preservation of the exact number of characters that are originated in a message in the case of message communications, or per unit time, in the case…
character-steppedPertaining to control of start-stop teletypewriter equipment in which a device is stepped one character at a time.
characteristic distortionIn telegraphy, the distortion caused by transients that, as a result of previous modulation, are present in the transmission channel.
characteristic frequencyA frequency which can be easily identified and measured in a given emission. A carrier frequency may, for example, be designated as the characteristic…
characteristic impedance (Zo)The impedance of a circuit that, when connected to the output terminals of a uniform transmission line of arbitrary length, causes the line to appear…
charging reference locationIn Universal Personal Telecommunications Service, the geographical location that may be used by the UPT service providers to determine the…
ChatSee Instant messaging (IM). A form of real-time communication between two or more people based on typed text.
chat roomAn Internet relay chat (IRC) channel designated for the real-time exchange of text messages.
chat scriptA batch of commands and responses, prerecorded on a terminal computer, for the purpose of facilitating easy or automatic access to a network.
CheckA written order instructing a financial institution to pay immediately on demand a specified amount of money from the check writer's account to the person…
check bitA bit, such as a parity bit, derived from and appended to a bit string for later use in error detection and possibly error correction. 2.
check characterA character, derived from and appended to a data item, for later use in error detection and possibly error correction.
Check DigitOne digit, usually the last, of an identifying field is a mathematical function of all of the other digits in the field.
check loopA device that is attached to interconnect the Go and Return paths of a circuit at the incoming end of a circuit on command to permit maintenance personnel…
check sequence (CS)A 16-bit sequence in the last two octets of a frame (excluding flags) that offers a cyclic redundancy check (CRC).
check wordCipher text generated by cryptographic logic to detect failures in cryptography. [INFOSEC-99]
checkboxAn element in a Web page's interactive form that allows users to select an option associated with that element.
checking codeMachine instructions used in the detection or interpretation of certain data or data fields from a diskette, for the purpose of determining whether the…
checksumA computed value that depends on the contents of a file. It is stored with data to detect file corruption.
checkvalueIn cryptography, a computed value that results from passing a data value through an irreversible algorithm. [After X9.24]
chip rateThe rate of encoding. [NTIA] 2. In direct-sequence-modulation spread-spectrum systems, the rate at which the information signal bits are transmitted as a…
chip timeIn spread-spectrum systems, the duration of a chip produced by a frequency-hopping signal generator.
chirpingThe rapid changing, as opposed to long-term drifting, of the frequency of an electromagnetic wave.
chosen-plaintext attackIn cryptography, an analytical attack in which a cryptanalyst can submit an unlimited number of plaintext messages and examine the corresponding…
chroma keyingIn television, nearly instantaneous switching between multiple video signals, based on the state, i.e.
chroma noiseNoise that manifests itself in a video picture as colored snow. [After Silicon]
chromatic dispersionA commonly used (but redundant) synonym for material dispersion. See dispersion.
chromaticity diagramA two-dimensional Cartesian plot that depicts the multidimensional subjective relationship among colors perceived by the normal human visual system (eyes…
chrominanceThe difference between a color and a specified reference color having a specified chromaticity and an equal luminance. [After Laurin]
chrominance signalIn color television, that signal or portion of the composite signal that bears the color information.
Chronic TrunkTrunk: A trunk experiencing a much higher then normal rate of failure or switching irregularities, over a period of time, with resulting high incidence of…
CIEAbbreviation for Commission International de l'Eclairage (International Commission on Illumination).
CipherSeries of transformations that converts plaintext to ciphertext using the Cipher Key.
Cipher SystemA cryptographic system in which cryptography is applied to plain text elements of equal length.
cipher text1. Enciphered information. [INFOSEC-99] Note: Cipher text is the result obtained from enciphering plain or encoded text. 2.
cipher text auto-keyCryptographic logic that uses previous cipher text to generate a key stream. [INFOSEC-99]
ciphertext stringIn cryptography, ciphertext that is formed by encrypting concatenated encryption elements. [After X9.23]
ciphertext substringIn cryptography, a segment of a ciphertext string. [After X9.23]
ciphonyThe process of enciphering audio information, resulting in encrypted speech. [INFOSEC-99] Note: "Ciphony" is a contraction of "ciphered telephony ."
CircuitA device, or system of devices, that allows electrical current to flow through it and allows voltage to occur across positive and negative terminals.
circuit identification codeInformation identifying a circuit between a pair of exchanges, for which signaling is being performed (14 bits in the ISDN user part). [T1.110-1987]
circuit kilometersThe route kilometers of revenue producing circuits in service, determined by measuring the length in terms of kilometers, of the actual path followed by…
circuit noise levelAt any point in a transmission system, the ratio of the circuit noise at that point to an arbitrary level chosen as a reference.
circuit reliability (CiR)The percentage of time a circuit was available for use in a specified period of scheduled availability.
circuit restorationThe process by which a communications circuit is established between two users after disruption or loss of the original circuit.
circuit routing: In open systems architecture, the logical path of a message in a communications network based on a series of gates at the physical network layer in the…
circuit switchingA method of routing traffic through a switching center, from local users or from other switching centers, whereby a connection is established between the…
circuit switching unit (CSU)Equipment used for routing messages over common-user circuits that interconnect a source data terminal equipment (DTE) to a sink DTE for information…
circuit transfer modeIn ISDN applications, a transfer mode by means of permanent allocation of channels or bandwidth between connections.
circuit-switched data transmission serviceA data transmission service requiring the establishment of a circuit-switched connection before data can be transferred from source data terminal…
circular polarizationIn electromagnetic wave propagation, polarization such that the tip of the electric field vector describes a helix.
circulatorA passive junction of three or more ports in which the ports can be accessed in such an order that when power is fed into any port it is transferred to…
civisionThe application of cryptography to television signals. 2. Television signals that have been enciphered to preserve the confidentiality of the transmitted…