1
1
Midterm
October 29, 2008
CS 392/6813: Computer Security
Fall 2009
[100pts, 2:00 hrs]
Name
:
____________________________
Student ID
:
____________________________
392 or 6813
:
____________________________
Instructions (please carefully read these first)
Write clearly your name, student id and course number above
The exam consists of
o
Problem 1 (with 11 subparts) worth 20pts,
o
Problem 2 worth 20pts,
o
Problem 3 (with 3 subparts) worth 30pts, and
o
Problem 4 worth 30pts.
There are a total of
10
singlesided sheets. Make sure that you have the complete
set
Problems which are more or less objective (i.e., where I don’t ask you to explain
your answer, why/why not etc.) should be answered objectively and concisely.
Write your answers in the space provided
Problems which are somewhat subjective (i.e., where I want you to explain your
reasoning) should be answered in detail showing all steps. Write your answers in
the space provided. If you run out of space, feel free to ask for extra sheets and I
will provide them to you. You can also use blank sides of the sheets in your exam
for doing rough/scratch work. Just separate out the “rough/scratch work” from
“actual work” clearly
Your goal is to maximize your score. Spend more time on questions you think you
know better than the ones you think you do not. Take a look at the whole exam
first, and plan your strategy accordingly
If you have any question/doubts, raise your hand and I’ll come to you for
clarifications
This exam is strictly CLOSED BOOK. No cheat sheets/books are allowed. No
collaboration of any sort is allowed. Violators will, at least, fail the course!
Calculators are NOT allowed. In fact, you don’t need them at all.
The exam finishes at 8:15pm sharp. I want your pens/pencils off your sheets
right away. Violators will, at least, fail the course!
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Problem 1 [20pts]
1.
[2pts]
Facial Recognition is a method of authentication based on:
a.
“something you have”
b.
“something you know”
c.
“something you are”
Something you are
2.
[2pts]
Let n be a product of two large primes p, q, i.e. n=pq. If x and y are two
numbers relatively prime to n such that x = y (mod n), and g is relatively prime to
n. Is g
x
= g
y
(mod n)?
Why/why not?
Since x
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 Fall '09
 Saxena
 Cryptography, Computer Security, attack, encryption scheme, Alice B, bitwise complement

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