# Symmetric Ciphers Questions and Answers – Principles of PRNG – I

This set of Cryptography Multiple Choice Questions & Answers (MCQs) focuses on “Principles of PRNG”.

1. PRNG stands for
a) Personal Random Number Generation
b) Pseudo Random Number Generation
c) Primitive Number Generators
d) Private Number Generators

Explanation: PRNG stands for Pseudo Random Number Generation.

2. TRNG stands for
a) True Random Number Generation
b) Trust Random Number Generation
c) Text Ring Number Generators
d) None of the mentioned

Explanation: TRNG stands for True Random Number Generation.

3. A rule to check for a large number N being a prime number
a) by dividing N by every even interger less than N/2
b) by dividing N by every odd interger less than root(N)
c) by dividing N by every even interger less than root(N)
d) by dividing N by every interger less than N/2

Explanation: A rule for checking if a number N is a prime is by dividing N by every odd interger less than root(N).

4. PRNGs are derived through algorithms.
a) True
b) False

Explanation: PRNGs are derived through algorithms. These algorithms are deterministic and therefore produce sequences of numbers that are not statistically random. Thus we should choose an algorithm which provides a high degree of randomness.

5. TRNGs take in an input which is referred to as
a) random variable
b) external variable
c) entropy source
d) bit stream

Explanation: TRNGs use an input known as “entropy source” which is an input source that is effectively random.

6. PRNGs take in an input which is referred to as
a) bit stream
b) seed
c) entropy source
d) external variable

Explanation: PRNGs use an input known as “seed”. The seed is usually generated using a TRNG.

7. Which of the following produces an output of fixed length?
a) PRNG
b) TRNG
c) PRF
d) All of the mentioned

Explanation: Only PRFs produce an output of fixed length. TRNGs and PRNGs have open ended outputs.

8. Which of the following a is NOT a check for randomness?
a) Uniformity
b) Scalability
c) Consistency
d) All of the mentioned

Explanation: Uniformity, Scalability and Consistency are all checks for randomness of a PRNG.

9. The property that there should be equally likely number of 1s and 0s in a Pseudo Random Number sequence is
a) Scalability
b) Uniformity
c) Stability
d) Consistency

Explanation: This is the property of Uniformity.

10. The property that any extracted subsequence should pass the test for randomness is
a) Scalability
b) Uniformity
c) Stability
d) Consistency

Explanation: Scalability is the property where any extracted subsequence should pass the test for randomness.

Sanfoundry Global Education & Learning Series – Cryptography and Network Security.

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