Question

Hill cypher

Exercise: Execute the next cell to produce a message encrypted using the Hill cipher method [4]: cipher make_cipher cipher out [4]: 129, 41, 42, 75, 94, 103, 34, 43, 48, 44, 44, 64, 18, 23, 23, 80, 95, 116, 48, 48, 63, 46, 46, 66, 78, 87, 108, 61, 77, 85, 54, 66, 81, 70, 75·94, 58, 72, 87, 34, 50, 51, 86, 106, 120, 79,97, 116 58, 67, 83 The message starts with the word "CLASSIFIED use this information to decrypt the message. Note. The message and the cipher key will change each time you execute the above cell For credit 1) Show how you deduce the decryption matrix D.2) Following the procedure of the previous homework, dearypt the message loaded above Show your work within the Python notebook you submit, as much as possible (preferably, entirely) Several cells are inserted for your use below You may add more celis (using the Insert drop-down). You can include cells for explanatory (nion-code) texts such as this one, by changing the cell type from above from Code" to "Markdown. Double-clicking on a "Markdown" cell allows you to eait its content

Answer 1

the python code for hill cipher is as follows

import numpy as np
from numpy.linalg import inv

originalMessage = []
encryptKey = []


def get_user_input(value, msg):
    input = raw_input(msg)
    input = input.lower()
    for character in input:
        number = ord(character) - 96
        value.append(number)

get_user_input(originalMessage, 'Enter Message to Encrypt')
get_user_input(encryptKey, 'Enter decryption Key')

# Get the length of input
inputLen = len(originalMessage)
ceilInt = np.int(np.ceil(np.sqrt(inputLen)))**2

# Modulo, this is our n in nXn
modHelper = np.sqrt(ceilInt)
rows, cols = np.int(modHelper), np.int(modHelper)


# Create our empty matrix and fill it with our values
def build_matrix(matrix):
    # Create matrix
    value = np.zeros(shape=(rows, cols))

    # Append our values
    for (i, v) in zip(range(0, len(matrix)), matrix):
        r, c = i / cols, i % cols
        value[r, c] = v

    return value

originalMessage = build_matrix(originalMessage)
encryptKey = build_matrix(encryptKey)

# Multiply our message by our encrypt key
encryptedMessage = np.dot(originalMessage, encryptKey)
print(encryptedMessage)

# Inverse the encryption key for awesomeness
decryptionKey = inv(np.matrix(encryptKey))
print(decryptionKey)

# Our decrypted matrix is
decryptedMessage = np.dot(originalMessage, decryptionKey)
print(decryptedMessage)

you can execute it by running these in the jupyter notebook till spaces in each cell.

remember to run in order to get the perfect output of the cipher