Weeks 9 - Cryptographic attacks

Question 1

Substitution cipher?

Answer 1

encrypts plaintext by swapping each letter as directed by the key

Question 2

Frequency analysis?

Answer 2

used to decrypt ciphertext in substitution based ciphers.

Question 3

Mono-alphabetic substitution cipher?

Answer 3

a substitution cipher using only a single alphabet

Question 4

poly-alphabetic substitution cipher?

Answer 4

a substitute cipher using multiple alphabets

Question 5

cryptographic system involves 4 components?

Answer 5

1. plaintext
   2.algorithm
   3.a key
2. the ciphertext

Question 6

cryptographic attack?

Answer 6

an attack using cryptanalysis to recover plaintext without using the key as attacker has access

Question 7

cyphertext-Only Attack (COA)

Answer 7

attacker can monitor ciphertext only but not corresponding plaintext

Question 8

known plaintext attack (KPA)

Answer 8

attacker has access to plaintext and ciphertext. objective to guess the key or to engineer a cipher

Question 9

chosen plaintext attack (CPA)

Answer 9

attacker chooses plaintext to be encrypted but can read ciphertext, access key not known, use both to design algorithm to mimic encryption process to decrypt ciphertext

Question 10

chosen ciphertext attack (CCA)

Answer 10

attacker chooses ciphertext to be encrypted but can read plaintext, access key not known, use both to design algorithm to mimic encryption process to decrypt ciphertext

Question 11

chosen key attack (CKA)

Answer 11

part of a key is known, cryptanalysis attempts to understand structure of the cipher

Question 12

differential cryptanalysis

Answer 12

It uses a set of ciphertext and related plaintext that are encrypted with the same key and attempts to decipher the key.