Assignment 2: Definitions, Access Control Matrices

Start date 2 September, due 9 September beginning of class.

Complete the following exercises (numbers are book chapter/section/exercise):

1. 1.12 1. e. Give a brief (2-3 sentence) justification of your answer.
2. 1.12 2. e.
3. 1.12 3.
4. 1.12 8.
5. 2.8 5. a. Also describe a mechanism by which s could be explicitly denied rights, and if q was specifically denied a right over s, then the copy_all_rights would not copy that right. Remember that testing for absence of a right isn't allowed (see end of Section 2.3.1)
6. Describe the fundamental reason why safety for biconditional monotonic protection systems is undecidable, but monoconditional are (Theorem 3-6 and 3-7). Proving both theorems would be one way to do this, but what I really want to see is that you understand why biconditional systems are fundamentally harder.
   You may go to the source literature if you have a hard time. If you do, please read the paper, the put it aside for a day before working through the problem on your own. A verbatim parroting of the Harrison-Ruzzo proof will result is a lower score that if you've obviously figured it out on your own.

Turning in assignment

Electronic submission preferred, using the turnin command (on mentor.ics.purdue.edu, turnin -c cs526 -p asn2 filename) if possible. If you don't yet have access to mentor, and/or turnin doesn't work from other machines, then email to cs526@ics.purdue.edu. Pdf is the safest for capturing non-text, please check with the TA for formats other than text or pdf. If emailed as an attachment, use your career account ID (followed by appropriate file type extension) as the file name. Hard copy is acceptable, please hand in at the beginning of class.