Week 10

Question 1

Define the terms monoalphabetic and polyalphabetic cipher

Question 2

Recognise from the description of a cipher whether it is monoalphabetic or polyalphabetic

Question 3

Describe the Vigenère Cipher

Question 4

Perform encryption and decryption using the Vigenère Cipher

Question 5

Describe how to use frequency analysis to attack the Vigenère Cipher when the key length is known

Question 6

Define the Index of Coincidence

Question 7

Compute the Index of Coincidence of [a given sequence]

Question 8

Describe how to apply the Index of Coincidence to a ciphertext resulting from the Vigenère Cipher in order to determine the key length

Question 9

Describe the Kasiski Test

Question 10

Apply the Kasiski test to a ciphertext resulting from the Vigenère Cipher in order to determine the key length

Question 11

Describe the Vernam Cipher

Question 12

Perform encryption and decryption using the Vernam Cipher