Homework Problems
  1. Read the article on the confused deputy at http://www.skyhunter.com/marcs/capabilityIntro/confudep.html. Explain why the deputy is confused and what can be done to prevent this problem.

  2. With respect to Bell-LaPadula (BLP), define subject, object, the simple security condition, the star property, the tranquility property and the weak tranquility property. Explain why BLP can be summarized as no read up, no write down.

  3. Explain why the low water mark principle (the Biba model) applies to data integrity.

  4. The book at http://www.radium.ncsc.mil/tpep/library/rainbow/NCSC-TG-030.html discusses covert channels. Read and briefly summarize two of the following sections: 2.2, 3.2, 3.3, 4.1, 4.2, 5.2, 5.3 or 5.4.

  5. Give two simple examples of covert channels. At least on example must be in the context of a multi-level security (MLS) system.

  6. Consider the statement "Some kinds of security mechanisms may be worse than useless if they can be compromised." Does this hold true for encryption? Why or why not? Does this hold true for inference control? Why or why not?