4.1 What is This Assignment’s Purpose?🔗

A critical part of achieving security is to have multiple people review things and spot weaknesses that others missed. That’s true of language-based security as well. You will now review, and give feedback on, the security policies written by your classmates.

Part of a review is mechanical: Is it a lattice? Does it meet the table? A program could do that part, and you should do it quickly and move on. Your focus should be on the parts that need human judgment: the cells the author chose to fill, any permissions you consider stray, and how the composite documents were handled.

4.2 Assignment🔗

As you review, keep an eye out for the following (but comment on other things you notice, too):

• Is it a lattice, and does it meet the table? One bottom, one top, a unique least upper bound for every pair; every M and X in the company’s table respected, and the two composite documents readable by the roles required and not by the roles forbidden. Report anything that fails. If nothing does, indicate that.

• The cells the author filled. For each one, do you agree? Where you don’t, say why, and follow the consequences through the lattice: a cell filled one way can force other reads through joins. Where you do agree, say so briefly.

• Stray reads. For each role, what can it read that the table left blank and the author did not explicitly take a position on? Some of these are harmless; others are granting excessive or unwanted permission. Say which you think these are.

• The composite documents. Which label did each one get, and how did the author arrange that: an added label, a moved clearance, something else? Do you agree with the choice, and with who can now read the document as a result?

Structure your answer by the above categories. You can of course have an additional category where you list things not covered by the above list but that you think are important.

Be concrete, precise, and concise.

It is absolutely forbidden to use AI to perform the review or to do the writeup. We aren’t trying to teach AI anything, we’re trying to teach you, the student.

4.3 What To Hand In🔗

Turn in a single document containing your review.