Consider a computer system with three users: Alice, Bob and Cindy. Alice owns the file alicerc, and Bob and Cindy can read it. Cindy can read and write the file bobrc, which Bob owns, but Alice can only read it. Only Cindy can read and write the file cindyrc, 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 cindyrc, and Alice removes Bob's ability to read alicerc. Show the new access control matrix.

c) Show the access control list for the latter scenario (you do not need to draw a diagram - just list the different entries).