ISA 662, Fall 2006, Assignment 2
Due before class: 06/23/08. No late submissions please.
Please submit electronic copy to: [email protected] with subject line
“ISA562 HM2”
This is an individual assignment. You are required to solve it on your own using
whatever material you like. Please sign and submit the following honor code statement
with your solution:
I have not taken any help on this examination from anyone and not provided any help to
anyone. The solution has been entirely worked out by me and represents my individual
effort.
Please submit a typed solution with the signed honor code statement.
1. Consider the set of rights {read, write, execute, append, list, modify, own}.
o Using the syntax in Bishop Section 2.3, write a command
delete_all_rights(p, q, s). This command makes p delete all the rights
that subject q has over object s.
o Then modify the command so that deletion only occurs if p has modify
rights over s.
2. Given the security levels TOPSECRET, SECRET, CONFIDENTIAL, and
UNCLASSIFIED (ordered from highest to lowest), and the categories A, B, and
C, state what type of access (read, write, both or neither) is allowed in the
following situations. Assume discretionary access controls allow anyone access
unless otherwise specified
o Paul, who is cleared for (TOPSECRET, { A, C}), wants to access a
document classified (SECRET, { B, C }).
o Anna, who is cleared for (CONFIDENTIAL, { C}), wants to access a
document classified (CONFIDENTIAL, { B}).
o Jesse, who is cleared for (SECRET, { C }), wants to access a document
classified (CONFIDENTIAL, { C}).
o Sammi, who is cleared for (TOPSECRET, { A, C}), wants to access a
document classified (CONFIDENTIAL, { A}).
o Robin, who has no clearances (and thus works at the UNCLASSIFIED
level), wants to access a document classified (CONFIDENTIAL, { B}).
3. Consider the take-grant example discussed in class, consider the following
situations:


Alice is a support worker who has the authority to read the documents,
including those containing proprietary information, whenever she wishes,
with the understanding she is not to pass any sensitive data to anyone else,
including co-workers and superiors.
Bob is a co-worker of Alice Based the first take-grant graph, can he steal
any information from Alice? Give the reasoning for your answer.
Bob
t
r
Data
Alice
co-workers
o
Consider the second graph. Can Donna steal the data? Again, give the
reasoning for your answer.
Donna
r
r
t
Kathy
co-workers
Alice
Data