Assignment 4: Confidentiality/Integrity Policy

Start date 23 September, due beginning of class 30 September.

Protection Models: Exercises from the Book

Complete the following exercises from the book Sections 4.11 and 5.8:

• 4.11.3 (try to find the reference...)
• 5.8.2 b.
• 7, but answer for raising the level of a subject, not an object (this is raising the maximum security level.)

Modeling Multics in the Bell-LaPadula Security Model

For each of the following, give code for the rule and a proof that your rule is secure. The level of detail should be comparable to Theorem 5-15.

Remember that for discretionary access control, to alter a subjects permission on an object requires having write on the parent of that object, except for the funny behavior near root.

1. get-write
2. release-append
3. give-write
4. rescind-write

Turning in assignment

Electronic submission preferred, using the turnin command (on mentor.ics.purdue.edu, expert.ics.purdue.edu, and possibly other machines; turnin -c cs526 -p asn3 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.