OS-Access Control Matrix

One way to control access to files is to create a two-dimensional access control matrix listing all the users and all the files in the system. The entry Aij is 1 if user i is allowed access to file j

Otherwise Aij=0. In an installation with a largae number of users and a large number of files, this matrix would be very large and very sparse. Allowing one user access to another users files.

To make a matrix concept useful, it would be necessary to use codes to indicate various kinds of access such as read only, write only, execute only, read write etc.


A technique that requires considerably less space is to control access to various user classes. A common classification scheme is
  1.  Owner – Normally, this is the user who created the file.
  2.  Specified User - The owner specifies that another individual may use the file.
  3.  Group or Project – Users are often members of a group working on a particular project. In this case the various members of the group may all be granted access to each other’s project-related files.
  4.  Public- Most systems allow a file to be designated as public so that it may be accessed by any member of the system’s user community. Public access normally allows users to read or execute a file, but not to write it.
OS-Access Control Matrix Reviewed by 1000sourcecodes on 22:40 Rating: 5
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