Cryptographic Hash Functions: Course Overview

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What is the purpose of a cryptographic hash function?

To generate truly random numbers

To turn text into a fixed-length value called a hash (correct)

To decode encrypted messages

To encrypt data with a secret key

Which type of algorithm depends on the use of a secret key?

Pseudorandom number generator

Keyless algorithm

Asymmetric encryption algorithm

Symmetric encryption algorithm (correct)

What does a pseudorandom number generator produce?

A sequence of Fibonacci numbers

A deterministic sequence of numbers or bits that appears random (correct)

A sequence of prime numbers

A random sequence of numbers

In symmetric encryption, what does an encryption algorithm take as input?

Data to be protected and a secret key (B) Signup and view all the answers

What properties make a cryptographic hash function useful for cryptography?

Fixed-length output and deterministic behavior (D) Signup and view all the answers

What distinguishes a single-key cryptographic algorithm from others?

Depends on the use of a secret key (C) Signup and view all the answers

What is the purpose of using a secret key in the permutation process?

To make the permutation look random without the key (D) Signup and view all the answers

In public-key encryption, what component is responsible for producing the scrambled message?

Encryption algorithm (C) Signup and view all the answers

What is the role of the decryption algorithm in public-key encryption?

Converts ciphertext back to original plaintext (C) Signup and view all the answers

What are the essential steps in public-key encryption?

Generating a pair of keys and sharing one publicly (A) Signup and view all the answers

Which component in public-key encryption varies for two different keys even with the same message?

Ciphertext (C) Signup and view all the answers

What transformation does the encryption algorithm perform on the plaintext?

Converts plaintext to ciphertext (B) Signup and view all the answers

What is the average time required for exhaustive key search when using a 128-bit key?

5.4 x 10^1024 years (D) Signup and view all the answers

Which of the following statements about the key search time is true?

An increase in decryption speed by a factor of 1 trillion (10^12) significantly reduces the time required to break codes. (C) Signup and view all the answers

What is a permutation in the context of encryption algorithms?

An ordered sequence of elements with each appearing exactly once. (A) Signup and view all the answers

How many permutations are possible for a set S = {a, b, c}?

6 permutations (C) Signup and view all the answers

What does it mean for a function to be a permutation in encryption algorithms?

The function is reversible with one-to-one correspondence between inputs and outputs. (B) Signup and view all the answers

Which factor significantly affects the time required for exhaustive key search in symmetric encryption algorithms?

The number of alternative keys available. (A) Signup and view all the answers