IT 862 Spring 2004

Prof. Ravi Sandhu

Take-home Examination 1

 

Due in class on 2/19/04

 

This is an examination.  You must write the answer yourself without ANY discussion with anyone else.  You are free to consult whatever literature you choose to.  Your time is likely better spent thinking through the answer rather than trying to find it in the literature.

 

Provide a signed statement with your submission stating, I have not given help or taken help from anyone on this assignment.

 

All questions have equal weight.  Please answer each question in approximately 1 to 1½  pages, single-spaced.  2 pages is an upper limit.  Your answer should be a coherently written essay that flows and reads similar to a technical paper.  Your solution should be prepared in soft copy, although diagrams may be hand-drawn.  Please submit hard copy on the due date in class.  If you cannot make it to class on the due date submit via email to sandhu@gmu.edu or fax to 253 563 3509 before the class.

 

1.      Discuss the following comment from the 1992 TAM paper.
The mono-operational assumption has the unfortunate effect of making creation in HRU essentially useless.  A single primitive operation in HRU can create only an empty row and/or column in the matrix.  This new row/column is not attached to its creator in mono-operational systems.  There is therefore no way of distinguishing the children of one parent from another.
Further discuss a similar statement for the augmented HRU model which is defined as HRU extended to allow testing for absence of rights in the condition part of a command.

 

2.      Discuss the applicability of the safety problem in context of the ORCON policy in section 4 of the 1992 TAM paper.

 

3.      Discuss the footnote in the right hand column on page 128 of the 1992 TAM paper.  How would you capture this extension in TAM.