CSC 405 Introduction to Computer Security

Homework Assignment #5

(Due by 12/06/06)

Problems 1-- 4 in this assignment are in Section 6.12 (page 359) in the textbook.

  1. (15 points) Exercise 10
  2. (15 points) Exercise 12
  3. (10 points) Exercise 15
  4. (10 points) Exercise 17
  5. (30 points) Consider the following multilevel relation, where the S and P symbols within the cells represent whether the cell’svalue is sensitive or public, i.e., “Black      S” means that the value “Black” of  attribute Name is sensitive, “Green     P” means that  the value “Green” ofattribute Name is not sensitive.

Name

SSN

Phone

Rank

Black                   S

111-11-1111           S

111-1111              S

Clerk                  S

White                   P

222-22-2222           P

222-2222              P

Secretary            P

Green                   P

333-33-3333           P

333-3333              P

Clerk                  P

Brown                  P

444-44-4444           P

222-2222              P

Account              P

  1. (20 points) The following data describe fund raising for major political parties. C1, ..., C9 are specific contributors with the following attributes:

Contributor

Business area

Political leaning

Favoritism shown by administration

Geographic area

C1

Steel Democrat High

Northeast

C2

Steel Republican Medium

West

C3 Steel Independent Low

South

C4

Sugar Democrat Medium

Northeast

C5

Sugar Republican Low

Northeast

C6

Sugar Independent High

West

C7

Oil Democrat Low

South

C8

Oil Republican Hig

South

C9

Oil Independent Medium

West

Suppose a user has retrieve the following results through a sequence of queries:

Contributing group

Amount

Steel

270,000

Sugar

120,000

Oil

540,000

Democrats

186,000

Republicans

564,000

Independents

180,000

High favoritism

510,000

Low favoritism

174,000

Medium favoritism

246,000

Northeast

90,000

West

330,000

South

510,000

Note that none of the individual contributions are disclosed directly. However, the above query results do disclose these data indirectly. Find out a way to derive the contributions of C1, C2, …, C9.