Software Security
CSG 379/ Karl Lieberherr
============================================
Due date: September 27, 2004

The home directory of the course is:
http://www.ccs.neu.edu/home/lieber/courses/csg379/f04/
All paths in this hw are with respect to this directory.

f04.html is the course home page.

Reading assignment: Read on the average 3 chapters per week from the text book.
In 6 weeks you should be done.

Disclaimer:
If one of the homeworks takes too much time, only complete what you can do
in a reasnoable amount of time. The rest of the work you can do in the following week.

Part 1:
Monitoring Software Behavior
----------------------------

is an excellent defensive technique.

Let's assume that if the following calls:
open_account(i); ... no deposit(i, amount); ... close_account(i);
appear in sequence, you want to send a warning message.
An account is opened and closed without ever receiving a deposit.
... means any number of intermediate calls.

Write a AspectJ program that does this monitoring.
Write one or more Java programs to test your AspectJ program.

Turn in your AspectJ program and Java programs with their inputs/outputs.

Part 2:
Binder has a polynomial-time decision procedure
-----------------------------------------------

Consider the propositional case of a Binder program:

#f :- #g, #h.
#g.
#h.

This is with respect to the grammar in
daj/program.cd
(An example is in daj/program.input.)

Describe an algorithm that finds a satisfying assignment for
such a program in polynomial time in the size of the input.
#f :- #g, #h.

we interpret as the clause

f or !g or !h

! is negation.
Turn in your algorithm description in English.
Note: The algorithm is very simple.

Part 3:
Binder and role-based-access control
------------------------------------

Describe how we can use Binder to express role-based access control policies.

User1 plays role R1.
User2 plays role R3.

R3 is a subrole of role R1.

Role R1 has permission to read file f.

Question: Is User2 allowed to read file?

Translate this to Binder and use DAJ to syntactically check
your Binder security formula.

Copy the code in 

/home/lieber/.www/courses/csg379/f04/hw/2/test

into one of your directories and modifiy the program.input
file.

Follow the directions in:

/home/lieber/.www/courses/csg379/f04/daj/daj-directions

to set-up your CCIS environment and run the program.

The above link also tells you how to generate a parser 
yourself.


Part 4: Binder version 2
------------------------

Compare the version of Binder in

/home/lieber/.www/courses/csg379/f04/hw/2/test-look-ahead-2

with the version in

/home/lieber/.www/courses/csg379/f04/hw/2/test

Describe the difference between the two languages.
Which one is safer to use?
Which one do you prefer? What is the minimal look-ahead that 
is needed? 

====================

Where to turn in:

csg379-grader AT ccs.neu.edu

Questions to the same address: it reaches both Robbie and me.