Question 1

there are well-defined tests for determining uniform distribution
and independence to validate that a sequence of numbers is
random.

Accepted Answer

False

Question 2

If the PRF does not generate effectively random 128-bit output
values it may be possible for an adversary to narrow the
possibilities and successfully use a brute force attack.

Accepted Answer

If a Pseudorandom Function (PRF) does not generate effectively random 128-bit output values, it becomes more predictable. This predictability can allow an adversary to eliminate unlikely possibilities, thereby reducing the search space for a brute force attack and increasing its chances of success.

Question 3

A widely used technique for pseudorandom number generation is
an algorithm known as the linear congruential method.

Accepted Answer

The linear congruential method is indeed a widely used algorithm for generating sequences of pseudorandom numbers due to its simplicity and ease of implementation.

Question 4

A __________ takes as input a source that is effectively random.
A)PRF
B)BBS
C)PRNG
D)tRNG

Accepted Answer

A True Random Number Generator (tRNG) takes as input a source that is effectively random, such as physical phenomena.

Question 5

the stream cipher is similar to the one-time pad with a difference
being that a one-time pad uses a pseudorandom number stream
and a stream cipher uses a genuine random number stream.

Accepted Answer

A one-time pad uses a genuine random number stream, ensuring perfect secrecy, while a stream cipher typically uses a pseudorandom number stream generated by an algorithm, making it practical for repeated use but not perfectly secure.

Question 6

the principle requirement of random or pseudorandom number
generation is that the generated number stream be unpredictable.

Accepted Answer

The core principle of random or pseudorandom number generation is to produce a sequence of numbers that is unpredictable, ensuring that future numbers in the sequence cannot be determined or guessed based on the previous numbers, which is essential for applications requiring security and fairness, such as cryptography and simulations.

Question 7

three broad categories of cryptographic algorithms are commonly
used to create PRNGs: symmetric block ciphers, asymmetric
ciphers, and hash functions and message authentication codes.

Accepted Answer

These three categories of cryptographic algorithms are indeed commonly used to create Pseudo-Random Number Generators (PRNGs). Symmetric block ciphers can be used in modes that generate pseudo-random output from a fixed key. Asymmetric ciphers, although less common for PRNGs due to their computational complexity, can also be used to generate randomness. Hash functions and message authentication codes (MACs) are frequently used in the construction of PRNGs because they can take an input and produce a seemingly random output, which is difficult to predict without knowing the input.

Question 8

Random numbers play an important role in the use of encryption
for various network security applications.

Accepted Answer

Random numbers are crucial in encryption algorithms to generate keys that are unpredictable, making it difficult for unauthorized parties to decrypt the information without the correct key.

Question 9

With true random sequences each number is statistically
independent of other numbers in the sequence and therefore
unpredictable.

Accepted Answer

True random sequences are characterized by the statistical independence of each number from others in the sequence, making each number unpredictable based on previous numbers.

Question 10

A __________ is used to produce a pseudorandom string of bits of some fixed length.
A)PRF
B)PRNG
C)OFB PRNG
D)tRNG

Accepted Answer

The answer of A __________ is used to produce a...

Question 11

A pseudorandom number generator takes as input a fixed value called the __________ and produces a sequence of output bits using a deterministic algorithm.
A)seed
B)fixed skew
C)entropy source
D)keystream

Accepted Answer

A pseudorandom number generator uses a seed as a fixed input value. This seed, through a deterministic algorithm, generates a sequence of numbers that appears random but is actually predictable if the seed is known.

Question 12

the purpose of the Maurer's universal statistical test is to
determine whether the number of ones and zeros in a sequence
are approximately the same as would be expected for a truly
random sequence.

Accepted Answer

The Maurer's Universal Statistical Test is designed to evaluate the randomness of a sequence by analyzing the distribution and frequency of patterns, not just the balance between ones and zeros.

Question 13

the seed that serves as input to the PRNG must be secure for
cryptographic applications.

Accepted Answer

In cryptographic applications, the seed for a Pseudorandom Number Generator (PRNG) must be secure because if an attacker can predict or determine the seed, they can predict the PRNG's output, compromising the security of the system.

Question 14

A cryptographically secure pseudorandom bit generator is defined
as one that passes the least significant bit test.

Accepted Answer

A cryptographically secure pseudorandom bit generator (CSPRNG) must meet several criteria beyond just passing the least significant bit test. It should be indistinguishable from true randomness, pass various statistical randomness tests, and be secure against attacks, including knowing part of its output.

Question 15

the longer the keyword the more difficult the cryptanalysis.

Accepted Answer

Longer keywords typically increase the complexity of the encryption, making it harder for cryptanalysts to decipher the message without knowing the keyword.

Question 16

A source that is effectively random is referred to as __________ .
A)an open source
B)an entropy source
C)a keystream
D)a seed

Accepted Answer

An entropy source is referred to as effectively random, providing the unpredictability needed for cryptographic applications and secure random number generation.

Question 17

Examples of a pseudorandom function are decryption keys and
nonces.

Accepted Answer

Pseudorandom functions are algorithms that produce output which is indistinguishable from random, used in various cryptographic applications. Decryption keys and nonces are not examples of pseudorandom functions; instead, they are often inputs or components used alongside pseudorandom functions in cryptographic protocols.

Question 18

the security of Blum, Blum, Shub is based on the difficulty of
factoring n.

Accepted Answer

The security of the Blum, Blum, Shub (BBS) pseudo-random number generator is based on the difficulty of factoring the modulus n, which is the product of two large prime numbers, specifically chosen to be congruent to 3 modulo 4.

Question 19

A secret key for symmetric encryption that is generated for use for a short period of time is called a _________ .
A)strategic key
B)sequence key
C)session key
D)stream key

Accepted Answer

Session keys are used in symmetric encryption for a short period of time, typically for a single session, ensuring that the key is less vulnerable to theft and that data is more secure.

Question 20

the true random number generator may simply involve conversion
of an analog source to a binary output.

Accepted Answer

True random number generators (TRNGs) often use physical processes, such as electronic noise or other analog phenomena, and convert these into a binary output to generate numbers that are truly random.

Quiz 8: Random Bit Generation and Stream Ciphers

there are well-defined tests for determining uniform distribution and independence to validate that a sequence of numbers is random.

If the PRF does not generate effectively random 128-bit output values it may be possible for an adversary to narrow the possibilities and successfully use a brute force attack.

A widely used technique for pseudorandom number generation is an algorithm known as the linear congruential method.

A __________ takes as input a source that is effectively random.

the stream cipher is similar to the one-time pad with a difference being that a one-time pad uses a pseudorandom number stream and a stream cipher uses a genuine random number stream.

the principle requirement of random or pseudorandom number generation is that the generated number stream be unpredictable.

three broad categories of cryptographic algorithms are commonly used to create PRNGs: symmetric block ciphers, asymmetric ciphers, and hash functions and message authentication codes.

Random numbers play an important role in the use of encryption for various network security applications.

With true random sequences each number is statistically independent of other numbers in the sequence and therefore unpredictable.

A __________ is used to produce a pseudorandom string of bits of some fixed length.

A pseudorandom number generator takes as input a fixed value called the __________ and produces a sequence of output bits using a deterministic algorithm.

the purpose of the Maurer's universal statistical test is to determine whether the number of ones and zeros in a sequence are approximately the same as would be expected for a truly random sequence.

the seed that serves as input to the PRNG must be secure for cryptographic applications.

A cryptographically secure pseudorandom bit generator is defined as one that passes the least significant bit test.

the longer the keyword the more difficult the cryptanalysis.

A source that is effectively random is referred to as __________ .

Examples of a pseudorandom function are decryption keys and nonces.

the security of Blum, Blum, Shub is based on the difficulty of factoring n.

A secret key for symmetric encryption that is generated for use for a short period of time is called a _________ .

the true random number generator may simply involve conversion of an analog source to a binary output.