coupling efficiencyIn fiber optics, the efficiency of optical power transfer between two optical components.
coupling lossThe loss that occurs when energy is transferred from one circuit, circuit element, or medium to another.
coverNatural or manmade objects on the bottom of lakes, rivers, or impoundments, especially those that influence fish behavior.
coverageThe scope of protection provided by an insurance contract which includes any of the listed benefits in an insurance policy.
covert channel1. A transmission channel that may be used to transfer data in a manner that violates security policy. [2382-pt.8] 2.
covert storage channel1. [A] covert channel involving the direct or indirect writing to a storage location by one process and the direct or indirect reading of the storage…
Covert Timing ChannelA covert channel in which one process signals information to another by modulating its own use of system resources in such a way that this manipulation…
credentialDetailed information, which is acquired during authentication, that describes the user, any group associations, and other security-related identity…
CRENAbbreviation for Corporation for Research and Educational Networking. The organization resulting from the merger of BITNET and the academic computer…
crest factorThe peak-to-rms voltage ratio of an alternating current (ac) signal. [T1.401-1988]
critical angleIn geometric optics, at a refractive boundary, the smallest angle of incidence at which total internal reflection occurs.
critical areaAn operational area that requires specific environmental control because of the equipment or information contained therein.
critical frequencyIn radio propagation by way of the ionosphere, the limiting frequency at or below which a wave component is reflected by, and above which it penetrates…
critical infrastructureElements of a system that are so vital that disabling any of them would incapacitate the entire system. 2.
critical mechanismA mechanism within a Target of Evaluation whose failure would create a security weakness [ITSEC].
critical technical loadThat part of the total technical power load required for synchronous communications and automatic switching equipment.
critical wavelengthThe free-space wavelength that corresponds to the critical frequency. Note: The critical wavelength is equal, in meters, to the speed of light (3 × 108…
CRLAbbreviation for certificate revocation list. In cryptography, a list of revoked certificates.
cross assemblerAn assembler that can run symbolic-language input on one type of computer and produce machine-language output for another type of computer.
cross certificationEnables organizations to establish trust with other organizations so that users can verify the digital signature of messages sent by users in other…
cross couplingThe coupling of a signal from one channel, circuit, or conductor to another, where it is usually considered to be an undesired signal.
cross modulationIntermodulation caused by the modulation of the carrier of a desired signal by an undesired signal.
cross office checkA check made across the exchange to verify that an acceptable speech path exists. [T1.226-1992]
cross-band radiotelegraph procedureA radiotelegraph network operational procedure in which calling stations, such as ship stations, call other stations, such as shore stations, using one…
cross-connectionConnections between terminal blocks on the two sides of a distribution frame, or between terminals on a terminal block.
cross-office trunkA trunk that has its terminations within a single facility.
cross-platformPertaining to software that will run on more than one operating system (i.e., on more than one platform).
cross-polarized operationThe operation of two transmitters on the same frequency, but with polarizations in the opposite sense, e.g.
cross-site linkIn a satellite communications system, the signal power and control connections between the components of an Earth station.
crossbar switchA switch that has a plurality of vertical paths, a plurality of horizontal paths, and electromagnetic means, i.e.
crossfade1. In audio programming, recording, or mixing, to combine signals in such a manner that one channel or source fades out as another fades in, while…
crosspointA single element that (a) is in the array of elements that compose a switch and (b) consists of a set of physical or logical contacts that operate…
crosstalk (XT)1. Undesired coupling of a signal from one circuit, part of a circuit, or channel, to another. 2.
crosstalk couplingThe ratio of the power in a disturbing circuit to the induced power in the disturbed circuit observed at specified points of the circuits under specified…
Cryptanalysis1) Operations performed in defeating cryptographic protection without an initial knowledge of the key employed in providing the protection.
CRYPTOA designation or marking which identifies classified operational keying material, and which indicates that this material requires special consideration…
crypto-alarm[A] circuit or device that detects failures or aberrations in the logic or operation of crypto-equipment.
crypto-algorithm[A] well-defined procedure or sequence of rules or steps, or a series of mathematical equations used to describe cryptographic processes such as…
crypto-ancillary equipmentEquipment designed specifically to facilitate efficient or reliable operation of crypto-equipment, without performing cryptographic functions itself.
crypto-ignition key (CIK)[A] device or electronic key used to unlock the secure mode of crypto-equipment. [INFOSEC-99]
cryptochannelA complete system of crypto-communications between two or more holders. The basic unit for naval cryptographic communication.
cryptographic1. [The] art or science concerning the principles, means, and methods for rendering plain information unintelligible, and for restoring encrypted…
cryptographic check valueInformation which is derived by performing a cryptographic transformation (see cryptography) on a data unit [7498-2].
cryptographic componentHardware or firmware embodiment of the cryptographic logic. A cryptographic component may be a modular assembly, a printed wiring assembly, a…
cryptographic equipment (crypto-equipment)Any device that embodies cryptographic logic or performs one or more cryptographic functions (e.g., key generation, encryption, and authentication).
cryptographic hashA mathematical function that maps values from a large (or even very large) domain into a smaller range, and is (a) one-way in that it is computationally…
Cryptographic Hash FunctionA function that maps a bit string of arbitrary length to a fixed length bit string.
cryptographic informationAll information significantly descriptive of cryptographic techniques and processes or of cryptographic systems and equipment, or their functions and…
cryptographic initialization[A] function used to set the state of a cryptographic logic prior to key generation, encryption, or other operating mode. [INFOSEC-99]
Cryptographic KeyA value used to control cryptographic operations, such as decryption, encryption, signature generation or signature verification.
cryptographic key synchronizationThe ability for two nodes, that have cryptographically processed a transaction, to determine the identical transaction key. [After X9.24]
cryptographic logicThe embodiment of one (or more) crypto-algorithm(s) along with alarms, checks, and other processes essential to effective and secure performance of the…
cryptographic randomization[A] function that randomly determines the transmit state of a cryptographic logic. [INFOSEC-99]
CryptographyTechnique to scramble data to preserve confidentiality or authenticity.
cryptologicOf or pertaining to cryptology. [JP 1-02]
CryptologyThe science that deals with hidden, disguised, or encrypted communications. It includes communications security and communications intelligence.
cryptomaterialAll material including documents, devices, equipment, and apparatus essential to the encryption, decryption, or authentication of telecommunications.
cryptonetStations holding a common key. [INFOSEC-99] Note: Activities that hold key for other than use, such as cryptologistic depots, are not cryptonet members…
CryptoperiodTime span during which each key setting remains in effect.
cryptosynchronization[The] process by which a receiving decrypting cryptographic logic attains the same internal state as the transmitting encrypting logic. [INFOSEC-99]
cryptosystemAssociated COMSEC items interacting to provide a single means of encryption or decryption. [INFOSEC]
crystal oscillator (XO)An oscillator in which the frequency is controlled by a piezoelectric crystal. Note 1: A crystal oscillator may require controlled temperature because its…
CSMAAbbreviation for carrier sense multiple access.
CSMA/CAAbbreviation for carrier sense multiple access with collision avoidance.
CSMA/CDAbbreviation for carrier sense multiple access with collision detection.
CSU(1) Computer Software Unit. (2) Communications System Utilization.
cumulative transit delayThe total transit delay applicable for a data call obtained by summing the individual transit delays of all component portions of the data connection. [T1.
current billingThe combined amount of changes billed, excluding arrears. [47 CFR Pt.36-A]
cursorA graphic pointer used with a mouse to point to a location on a terminal screen.
curve-fitting compactionData compaction accomplished by substituting an analytical expression for the data to be stored or transmitted.
custom local area signaling service (CLASS)One of an identified group of network-provided enhanced services. Note: A CLASS group for a given network usually includes several enhanced service…
Customer1. The person or organization that purchases a Target of Evaluation [ITSEC]. 2. The corroboration that the source of data received is as claimed.
customer accessIn an Integrated Services Digital Network (ISDN), the portion of the ISDN access that a network provider supplies to connect the customer, i.e.
customer dialed charge trafficTraffic which is both (a) handled to completion through pulses generated by the customer and (b) for which either a message unit charge, bulk charge or…
customer installation (CI)All telecommunication equipment and wiring on the customer side of the network interface. [T1.Rpt37-1994]
customer management complexIn network management, a complex that (a) is controlled by a customer and (b) is responsible for, and performs, maintenance for the customer installation.
customer office terminalTermination equipment that (a) is located on the customer premises and (b) performs a function that may be integrated into the common carrier equipment.