"""Affine Cipher Hacker
Implements a function that can hack an affine cipher encrypted message.
Attributes:
SILENT_MODE (bool): Specifies whether to print all key attempts.
Note:
* https://www.nostarch.com/crackingcodes/ (BSD Licensed)
"""
from pythontutorials.books.CrackingCodesWithPython.Chapter14.affineCipher import decryptMessage, SYMBOLS, getKeyParts
from pythontutorials.books.CrackingCodesWithPython.Chapter13.cryptomath import gcd
from pythontutorials.books.CrackingCodesWithPython.Chapter11.detectEnglish import isEnglish
SILENT_MODE = True
[docs]def main():
from pyperclip import copy
# You might want to copy & paste this text from the source code at
# https://www.nostarch.com/crackingcodes/.
myMessage = """5QG9ol3La6QI93!xQxaia6faQL9QdaQG1!!axQARLa!!AuaRLQ
ADQALQG93!xQxaGaAfaQ1QX3o1RQARL9Qda!AafARuQLX1LQALQI1iQX3o1RN"Q-5!1RQP36ARu"""
hackedMessage = hackAffine(myMessage)
if hackedMessage is not None:
# The plaintext is displayed on the screen. For the convenience of
# the user, we copy the text of the code to the clipboard:
print('Copying hacked message to clipboard:')
print(hackedMessage)
copy(hackedMessage)
else:
print('Failed to hack encryption.')
[docs]def hackAffine(message: str):
"""Hacks affine cipher encrypted messages
Brute-forces a given encrypted message by looping through all the keys, checking if the result is English, and
prompting the user for confirmation of decryption.
Args:
message: String with message to brute-force.
Returns:
Prints out possible results and prompts user for confirmation. If confirmed, prints out and returns
full decrypted message, otherwise returns None.
"""
print('Hacking...')
# Python programs can be stopped at any time by pressing Ctrl-C (on
# Windows) or Ctrl-D (on macOS and Linux):
print('(Press Ctrl-C or Ctrl-D to quit at any time.)')
# Brute-force by looping through every possible key:
for key in range(len(SYMBOLS) ** 2):
keyA = getKeyParts(key)[0]
if gcd(keyA, len(SYMBOLS)) != 1:
continue
decryptedText = decryptMessage(key, message)
if not SILENT_MODE:
print('Tried Key %s... (%s)' % (key, decryptedText[:40]))
if isEnglish(decryptedText):
# Check with the user if the decrypted key has been found:
print()
print('Possible encryption hack:')
print('Key: %s' % key)
print('Decrypted message: ' + decryptedText[:200])
print()
print('Enter D for done, or just press Enter to continue hacking:')
response = input('> ')
if response.strip().upper().startswith('D'):
return decryptedText
return None
# If affineHacker.py is run (instead of imported as a module), call
# the main() function:
if __name__ == '__main__':
main()