Assignment #13 Solution



No programming for this assignment.
[100 points] Problem Set
1. [20 points] What are the main differences between capability lists and access lists?
2. [20 points] Consider a computing environment where a process is given the privilege
of accessing an object only n times. Suggest a scheme for implementing this policy.
3. [20 points] Capability lists are usually kept within the address space of the user.
How does the system ensure that the user cannot modify the contents of the list?
4. [20 points] 14.3 Consider a computer system in which computer games can be
played by students only between 10 P.M. and 6 A.M., by faculty members between 5
P.M. and 8 A.M., and by the computer center staff at all times. Suggest a scheme for
implementing this policy efficiently.
5. [20 points] 14.8 Discuss the need for rights amplification in Hydra. How does this
practice compare with the cross-ring calls in a ring-protection scheme?