Access control matrix and list

Simple exam question in information security could be writing a access control matrix.
Access control matrix is the most simplest Access control representation model. It is useful abstraction, but not very useful beyond that.

Very common exam question could be demonstrating file/folder permissions of users and groups in a access control matrix.

Example output of an ls -l command in terminal:

-rw-r----- pekka guard 123123 10 Jan 20:23 inmates.txt
-rw----r-- teppo inmate 1213 11 Dec 20:23 diary.txt
-rw-rw-r-- jukka guard 20328 09 Feb 11:00 announcements.txt

With this kind of a terminal output the Access control matrix would look like:

pekka teppo jukka
inmates.txt read, write read
diary.txt read read, write read
announcements.txt read, write read read, write

Access control list (ACL)

The same matrix representation of permissions could be turned into a access control list. Simply put, access control list contains list of object access rights.

By using the same terminal data as above lets make a access control list. The access control lists can be displayed in various format, as long as it is displayed as a list.

  • inmates.txt:
    • pekka: read, write
    • teppo: –
    • jukka: read
  • diary.txt:
    • pekka: read
    • teppo: read, write
    • jukka: read
  • announcements.txt:
    • pekka: read, write
    • teppo: read
    • jukka: read, write

These posts are done in a purpose of being my personal notes for Information Security course exam. Might contain some inaccurate information.