Cryptography Basics

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What is the goal of cryptanalysis?

To estimate the occurrence frequency of letters in a text
To find the equivalent representation of the encryption algorithm
To recover the plaintext or the key (correct)
To encrypt the plaintext securely

What type of attack tries to find an equivalent representation of the encryption algorithm to simplify it?

Algebraic attack (correct)
Differential cryptanalysis
Linear cryptanalysis
Statistical attack

What level of cipher security is theoretically unbreakable, regardless of the amount of time or ciphertext available?

Computationally secure
Theoretically secure
Unconditionally secure (correct)
Statistically secure

What is the main objective of a brute-force attack?

To try every possible key on a piece of cipher text until an intelligible translation is obtained (C) Signup and view all the answers

What is the main criterion for a computationally secure cipher?

The time required to break the cipher exceeds the useful lifetime of the information (C) Signup and view all the answers

What type of attack involves studying how the plaintexts difference propagates and affects the ciphertext difference?

Differential cryptanalysis (C) Signup and view all the answers

What is the primary characteristic of symmetric encryption?

Uses the same key for sender and receiver (D) Signup and view all the answers

What type of cipher uses different keys for the sender and receiver?

Asymmetric cipher (A) Signup and view all the answers

Which type of cipher processes input elements continuously, producing output one element at a time?

Stream cipher (D) Signup and view all the answers

What is the primary difference between block ciphers and stream ciphers?

Block ciphers process input one block at a time, while stream ciphers process input continuously (D) Signup and view all the answers

What is the purpose of a hash function in symmetric encryption?

To authenticate the sender (C) Signup and view all the answers

What is the primary advantage of asymmetric encryption over symmetric encryption?

Asymmetric encryption provides key exchange and digital signatures (D) Signup and view all the answers

What is the goal of encoding/decoding?

To represent data in a certain format (B) Signup and view all the answers

What is the role of Alice in the cryptosystem?

Sender of an encrypted message (C) Signup and view all the answers

What is the purpose of a cryptographic algorithm?

To disguise a message (D) Signup and view all the answers

What is the difference between a key and a keyspace?

A key is a specific value, while a keyspace is the range of possible values (C) Signup and view all the answers

What is the type of attack that exploits the characteristics of the algorithm?

Cryptanalytic attack (C) Signup and view all the answers

What is the purpose of non-repudiation?

To prevent denial by one of the parties in a communication (A) Signup and view all the answers