Final answer:
An access control matrix using the HRU approach represents the permissions associated with each subject-object pair in a system. The access control matrix is used in computer security to define the rights of subjects over objects, and the HRU model involves rules for modifying these rights.
Step-by-step explanation:
Access Control Matrix using HRU Approach
An access control matrix is a security model that describes the permissions associated with each subject-object pair in a system. The HRU (Harrison-Ruzzo-Ullman) model is one of the approaches to implement an access control matrix. In this model, the matrix is represented as a table with the subjects in rows and the objects in columns. Each entry in the matrix specifies the access rights of a subject to an object.
For example, let's say we have three subjects (A, B, C) and three objects (X, Y, Z). The access control matrix, using the HRU approach, would look like this:
XYZAReadWriteReadBWriteReadWriteCNo AccessReadNo Access
In the above example, subject A has read access to object X and Z, and write access to object Y. Subject B has write access to object X and Z, and read access to object Y. Subject C has no access to object X and Z, and read access to object Y.
The access control matrix is used in computer security to define the rights of subjects over objects, and the HRU model involves rules for modifying these rights. To draw an HRU-based matrix, list subjects and objects in rows and columns, respectively, and fill in the cells with the rights each subject has over each object. The HRU model allows for dynamic changes in rights through specific commands.
The access control matrix is a model used in computer security to represent the rights of each subject, such as a user or a program, with respect to various objects like files, directories, or system resources. The HRU (Harrison-Ruzzo-Ullman) approach is an access control model that defines a set of rules for state transitions which govern how rights can be passed around or modified.
To draw an access control matrix using the HRU approach, list all the subjects along the rows and the objects along the columns. Each cell in the matrix specifies the set of rights that the corresponding subject has over the object. For example, if a subject has the right to read and write to an object, the cell intersecting that subject's row and the object's column would contain the notations 'R' and 'W'.
One of the key concepts in the HRU model is the capability of subjects to dynamically change rights through specific commands. Commands may involve operations like grant, which gives a subject a certain right to an object, and revoke, which removes a right.