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*Fall 2001, CSE 597E: Quiz 4 and solution - 7 Nov 2001*

Please write your Name and Student ID at the top of the page.

**[2 point]**What is a pseudorandom number generator? (only one answer, please)

- A program that generates a sequence of pseudo numbers, i.e. rational numbers
that approximate real numbers
- A program which generates a sequence of numbers
having the appearance of randomness,
but nevertheless following a specific, deterministic algorithm.
- A program which generates numbers with a pseudo-uniform probabilistic distribution
- A nondeterministic program (pseudo-program) which generates numbers in a completely rand
omized way.

**[4 points]**
Pseudorandom generators are used in security protocols for (mark all correct answers)

- Nonces
- Session keys
- Assigning an identity to the attackers
- Parameters in digital signatures

**[2 points]**Which of the following is a characteristic of linear congruential ge
nerators
(only one answer, please)

- They are based on physical processes instead of programs
- The next number in the sequence is always greater than previous number
- The next number in the sequence is computed by using previous number
- They generate a linear sequence, i.e. numbers are never repeated (no loops).

**[2 points]**Which of the following is a characteristic of true random number gen
erators
(only one answer, please)

- They generate a monotonic sequence of numbers (in increasing order)
- They generate more numbers than the pseudorandom number generators
- They are more subject to attacks than the pseudorandom number generators
- They are based on physical processes instead of programs