access matrix

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access matrix

[′ak‚ses ‚mā·triks]
(computer science)
A method of representing discretionary authorization information, with rows representing subjects or users of the system, columns corresponding to objects or resources of the system, and cells (intersections of rows and columns) composed of allowable operations that a subject may apply to an object.
References in periodicals archive ?
The notations that will be used are described as follows: [absolute value of [C.sub.1]] denotes the bit size of an element in G; [absolute value of [C.sub.T]] denotes the bit size of an element in [G.sub.T]; [absolute value of [C.sub.p]] denotes the bit size of an element in [Z.sup.*.sub.p]; [C.sub.T] denotes the size of access control matrix associated with the ciphertext; [absolute value of [C.sub.k]] denotes the bit size of the key encryption key in Hur's scheme [13]; t denotes the number of attributes associated with the ciphertext; k denotes the number of attributes associated with the secret key of a user; [n.sub.a] denotes the number of all attributes in the system; [n.sub.u] denotes the number of all users in the system.
The public key in Yang's scheme grows linearly with the number [n.sub.a] of all attributes in the system and in Liang's scheme grows linearly with the number na of all attributes and the column vector CT/t of access control matrix with each other as the slope and in our scheme grows linearly with the number [n.sub.a] of all attributes and the number [n.sub.u] of all users, however, with constant slope compared with Liang's scheme.
In particular, the key generation time in Liang's scheme is associated with not only the number of attributes but also the column vector [C.sub.T]/t of access control matrix and the number [n.sub.u] of all users in the system; therefore, its key generation time is much larger than the other three schemes.
An access control matrix is used to control what a user can do with the files and/or programs he or she is authorized to access.

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