CISSP Practice

Entity integrity

A tuple in a relation cannot have a null value for any of the primary key attributes.

Entity-relationship-attribute (ERA) diagram

Used for data intensive application systems and shows the relationships between entities and attributes of a system.

Entrapment

The deliberate planting of apparent flaws in a system for the purpose of detecting attempted penetrations.

Entropy

(1) The uncertainty of a random variable. (2) A measure of the amount of uncertainty that an attacker faces to determine the value of a secret. Entropy is usually stated in bits.

Environmental failure protection

The use of features to protect against a compromise of the security of a cryptographic module due to environmental conditions or fluctuations outside of the module’s normal operating range.

Environmental failure testing

The use of specific test methods to provide reasonable assurance that the security of a cryptographic module will not be compromised by environmental conditions or fluctuations outside of the module’s normal operating range.

Environmental threats

Examples of environmental threats include equipment failure, software errors, telecommunications network outage, and electric power failure.

Ephemeral key pairs

Ephemeral key agreement keys are generated and distributed during a single key agreement process (e.g., at the beginning of a communication session) and are not reused. These key pairs are used to establish a shared secret (often in combination with static key pairs); the shared secret is subsequently used to derive shared keying material. Not all key agreement schemes use ephemeral key pairs, and when used, not all entities have an ephemeral key pair.

Ephemeral keys

Short-lived cryptographic keys that are statistically unique to each execution of a key establishment process and meet other requirements of the key type (e.g., unique to each message or session).

Equipment life cycle

Four phases of equipment life cycle (asset management) include: Authorization and acquisition (phase 1), Inventory and audit (phase 2), Use and maintenance (phase 3), and Dispose or replace (Phase 4). Inventory and audit includes tagging the assets, maintaining an inventory of electronic records, taking periodic inventory of these assets through physical counting, and reconciling the difference between the physical count and the book count. Maintenance includes preventive and remedial maintenance, which can be performed onsite, offsite, or both. Examples of equipment located in functional user departments and IT department include routers, printers, scanners, CPUs, disk drives, and tape drives.

Erasable programmable read-only memory (EPROM)

A subclass of ROM chip that can be erased and reprogrammed many times.

Erasure

A process by which a signal recorded on magnetic media is removed (i.e., degaussed). Erasure may be accomplished in two ways, (1) by alternating current (AC) erasure, by which the information is destroyed by applying an alternating high- and low-magnetic field to the media or (2) by direct current (DC) erasure, by which the media are saturated by applying a unidirectional magnetic field. Process intended to render magnetically stored information irretrievable by normal means.

Error

(1) The difference between a computed, observed, or measured value and the true, specified, or theoretically correct value or condition. (2) An incorrect step, process, or data definition often called a bug. (3) An incorrect result. (4) A human action that produces an incorrect result. (5) A system deviation that may have been caused by a fault. (6) A bit error is the substitution of a ‘0’ bit for a ‘1’ bit, or vice versa.

Error analysis

The use of techniques to detect errors, to estimate/predict the number of errors, and to analyze error data both singly and collectively.

Error correction

Techniques that attempt to recover from detected data transmission errors.

Error-correction code

A technique in which the information content of the error-control data of a data unit can be used to correct errors in that unit.

Error-detection code

A code computed from data and comprised of redundant bits of information designed to detect, but not correct, unintentional changes in the data.

Escrow

Something (e.g., a document or an encryption key) that is “delivered to a third person to be given to the grantee upon the fulfillment of a condition.”

Escrow arrangement