18 Questions
What can be constructed using secure PRFs and vice-versa?
Secure PRGs
In the context of computing the square root of x^2, what can be learned with only probability 1/2?
The sign of exact x
Which of the following is true about single message and multi-message CPA-security?
They are equivalent
How can a secure PRF be constructed from a PRG using the tree-construction?
By fixing the input of the function to always 0
What is a requirement for the length of plaintext in CBC mode encryption?
It should be a multiple of the block length
What is a characteristic of the stateful variant of Counter mode compared to OFB mode?
Secure in Counter mode, insecure in OFB mode
Which of the following is a characteristic of a secure PRG?
The outcome of the PRG is computationally indistinguishable from a true random generator
Which statement about PRGs is false?
A computationally unbounded adversary can determine the seed
What is the primary purpose of a Pseudo-Random Generator (PRG)?
To provide security against computationally bounded adversaries
Why is the output of a PRG considered deterministic?
Because it relies on the seed and a deterministic function
In what way does a PRG aim to overcome the limitations posed by perfect security?
By allowing encryption of long messages with short keys
What does an 'efficient' adversary refer to in the context of cryptographic schemes?
An adversary with almost infinite computational resources
Which of the following is a secure PRG according to the text?
G1 (s) = G(s1 ) ⊕ G(s2 ), where s = s1 ||s2 , and each si ∈ {0, 1}n
What is the probability distribution of G3 (s) in relation to a true random number generator?
Always all zeros
Why is G2 not considered a secure PRG according to the text?
First and second half of the output are the same
What does G4 do with the parity bit of s in relation to a secure PRG?
Appends it to the output
In the context of PRGs, why is XOR of two random/pseudorandom strings significant?
Produces another random/pseudorandom string
What is the significance of concatenation operation in the context of secure PRGs?
Creates predictable patterns
Test your knowledge on the relationship between secure Pseudorandom Generators (PRGs) and Pseudorandom Functions (PRFs). Questions cover topics like the construction of secure PRGs using secure PRFs, computing square roots, and the equivalence between single message and multi-message CPA-security.
Make Your Own Quizzes and Flashcards
Convert your notes into interactive study material.
Get started for free
