INFS 780, Fall 2004, Examination 2

Posted: 11/6/2004, Due in class: 11/23/04

Prof. Ravi Sandhu

 

This is a take-home, open-book and open-time examination.  You are required to solve it on your own.  The questions are based primarily on the papers and the material discussed in class.  You are welcome to use whatever material you like but it is unlikely you will find the answers anywhere.  The best approach would be to read and thoroughly understand the relevant portions of the papers and think through the answers.  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 or neatly handwritten solution with the signed honor code statement.  Keep a copy for your records and reference.  The process for grading the examination will be discussed in class.

 

ANSWER ALL 5 QUESTIONS IN MAXIMUM ONE PAGE EACH.  ALL QUESTIONS HAVE EQUAL WEIGHT.

 

  1. Explain why the safety proof for acyclic creation in SPM falls apart for cyclic creates.

 

  1. Consider the ORCON specification in the TAM paper. Give an ESPM specification for the monotonic commands in the ORCON TAM scheme.

 

  1. Discuss if the non-monotonic commands of the ORCON specification in the TAM paper satisfy the restoration principle and thereby can be ignored for safety analysis purposes.

 

  1. Theorem 1 in the TAM paper states that: “Every MTAM scheme has an equivalent scheme in canonical form.”  Discuss if this statement applies to TAM schemes in general.

 

  1. The TAM paper shows that “Ternary MTAM is equivalent in expressive power to MTAM,” and that “Binary MTAM is less expressive than ternary MTAM.”  Discuss if these statements apply to TAM in general.