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In the relational model of databases, a primary key is a designated attribute that can reliably identify and distinguish between each individual record in a table.The database creator can choose an existing unique attribute or combination of attributes from the table (a natural key) to act as its primary key, or create a new attribute containing a unique ID that exists solely for this purpose ...
Therefore, a relation can have multiple candidate keys, each with a different number of attributes. [2] Specific candidate keys are sometimes called primary keys, secondary keys or alternate keys. The columns in a candidate key are called prime attributes, [3] and a column that does not occur in any candidate key is called a non-prime attribute.
The former is called signature keys. stream key - the output of a stream cipher as opposed to the key (or cryptovariable in NSA parlance) that controls the cipher; training key - (NSA) unclassified key used for instruction and practice exercises. Type 1 key - (NSA) keys used to protect classified information. See Type 1 product.
One of those keys per table may be designated the primary key; other keys are called alternate keys. Any key may consist of one or more attributes. For example, a Social Security Number might be a single attribute key for an employee; a combination of flight number and date might be a key consisting of two attributes for a scheduled flight.
Since a current database stores only currently valid data, there is a one-to-one correspondence between a surrogate in the modeled world and the primary key of the database. In this case the surrogate may be used as a primary key, resulting in the term surrogate key. In a temporal database, however, there is a many-to-one relationship between ...
Public key transport keys are the public keys of asymmetric key pairs that are used to encrypt keys using a public key algorithm. These keys are used to establish keys (e.g., key wrapping keys, data encryption keys or MAC keys) and, optionally, other keying material (e.g., Initialization Vectors). Symmetric key agreement key
Public-key cryptography, or asymmetric cryptography, is the field of cryptographic systems that use pairs of related keys. Each key pair consists of a public key and a corresponding private key. [1] [2] Key pairs are generated with cryptographic algorithms based on mathematical problems termed one-way functions.
The CROWS system provides an operator with the ability to acquire and engage targets while inside a vehicle, protected by its armor. It is designed to mount on a variety of vehicle platforms and supports the Mk 19 grenade launcher , 12.7 mm M2 .50 Caliber Machine Gun , 7.62 mm M240B Machine Gun , and 5.56 mm M249 Squad Automatic Weapon .