Question

Consider a computer system with three users: Alice, Bob, and Cyndy. Alice owns the file alicerc, and Bob and Cyndy can read it. Cyndy can read and write the file bobrc, which Bob owns, but Alice can only read it. Only Cyndy can read and write the file cyndyrc, which she owns. Assume that the owner of each of these files can execute it.

a. Create the corresponding access control matrix.
b. Cindy gives Alice permission to read cyndyrc, and Alice removes Bob's ability to rad alicerc. Show the new access control matrix.

Answer 1

Following are the solution to this question:

Step-by-step explanation:

For point a:

`alicerc \ \ \ \ \ \ \ \ \ \ \ bobrc \ \ \ \ \ \ \ \ \ \ \ \ \ \ cyndyrc\\`

`Alice \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ ox \ \ \ \ \ \ \ \ \ \ \ \ \ \ r\\\\ Bob \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ r \ \ \ \ \ \ \ \ \ \ \ \ \ \ ox \\\\Cyndy \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ r\ \ \ \ \ \ \ \ \ \ \ \ \ \ rw \ \ \ \ \ \ \ \ \ \ \ \ \ \ orwx`

For point b:

`alicerc \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ bobrc \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ cyndyrc`

`Alice \ \ \ \ \ \ \ \ \ \ \ \ \ \ ox \ \ \ \ \ \ \ \ \ \ \ \ \ \ r \ \ \ \ \ \ \ \ \ \ \ \ \ \ r\\\\Bob \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ ox \\\\Cyndy \ \ \ \ \ \ \ \ \ \ \ \ \ \ r \ \ \ \ \ \ \ \ \ \ \ \ \ \ rw \ \ \ \ \ \ \ \ \ \ \ \ \ \ orwx`