Hacking Monoalphabetic Cipher
In this chapter, you will learn about monoalphabetic cipher and its hacking using Python.
Monoalphabetic Cipher
A Monoalphabetic cipher uses a fixed substitution for encrypting the entire message. A monoalphabetic cipher using a Python dictionary with JSON objects is shown here −
monoalpha_cipher = { 'a': 'm', 'b': 'n', 'c': 'b', 'd': 'v', 'e': 'c', 'f': 'x', 'g': 'z', 'h': 'a', 'i': 's', 'j': 'd', 'k': 'f', 'l': 'g', 'm': 'h', 'n': 'j', 'o': 'k', 'p': 'l', 'q': 'p', 'r': 'o', 's': 'i', 't': 'u', 'u': 'y', 'v': 't', 'w': 'r', 'x': 'e', 'y': 'w', 'z': 'q', ' ': ' ', }
With help of this dictionary, we can encrypt the letters with the associated letters as values in JSON object. The following program creates a monoalphabetic program as a class representation which includes all the functions of encryption and decryption.
from string import letters, digits from random import shuffle def random_monoalpha_cipher(pool = None): if pool is None: pool = letters + digits original_pool = list(pool) shuffled_pool = list(pool) shuffle(shuffled_pool) return dict(zip(original_pool, shuffled_pool)) def inverse_monoalpha_cipher(monoalpha_cipher): inverse_monoalpha = {} for key, value in monoalpha_cipher.iteritems(): inverse_monoalpha[value] = key return inverse_monoalpha def encrypt_with_monoalpha(message, monoalpha_cipher): encrypted_message = [] for letter in message: encrypted_message.append(monoalpha_cipher.get(letter, letter)) return ''.join(encrypted_message) def decrypt_with_monoalpha(encrypted_message, monoalpha_cipher): return encrypt_with_monoalpha( encrypted_message, inverse_monoalpha_cipher(monoalpha_cipher) )
This file is called later to implement the encryption and decryption process of Monoalphabetic cipher which is mentioned as below −
import monoalphabeticCipher as mc cipher = mc.random_monoalpha_cipher() print(cipher) encrypted = mc.encrypt_with_monoalpha('Hello all you hackers out there!', cipher) decrypted = mc.decrypt_with_monoalpha('sXGGt SGG Nt0 HSrLXFC t0U UHXFX!', cipher) print(encrypted) print(decrypted)
Output
You can observe the following output when you implement the code given above −
![Monoalphabetic](https://www.tutorialspoint.com/cryptography_with_python/images/monoalphabetic.jpg)
Thus, you can hack a monoalphabetic cipher with specified key value pair which cracks the cipher text to actual plain text.
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