Chapter 16 – Hacking the Affine Cipher 227

8. def main():


9. 
   

   You might want to copy & paste this text from the source code at

   
   


10. 
    

    http://invpy.com/affineHacker.py

    
    


11. myMessage = """U&'<3dJ^Gjx'-3^MS'Sj0jxuj'G3'%j'<mMMjS'g{GjMMg9j{G'g"'gG
    '<3^MS'Sj<jguj'm'P^dm{'g{G3'%jMgjug{9'GPmG'gG'-m0'P^dm{LU'5&Mm{'_^xg{9"""


12. 
    


13. hackedMessage = hackAffine(myMessage)


14. 
    


15. if hackedMessage != None:


16. 
    

    The plaintext is displayed on the screen. For the convenience of

    
    


17. 
    

    the user, we copy the text of the code to the clipboard.

    
    


18. print('Copying hacked message to clipboard:')


19. print(hackedMessage)


20. pyperclip.copy(hackedMessage)


21. else:


22. print('Failed to hack encryption.')


23. 
    


24. 
    


25. def hackAffine(message):


26. print('Hacking...')


27. 
    


28. 
    

    Python programs can be stopped at any time by pressing Ctrl-C (on

    
    


29. 
    

    Windows) or Ctrl-D (on Mac and Linux)

    
    


30. print('(Press Ctrl-C or Ctrl-D to quit at any time.)')


31. 
    


32. 
    

    brute-force by looping through every possible key

    
    


33. for key in range(len(affineCipher.SYMBOLS) ** 2):


34. keyA = affineCipher.getKeyParts(key)[0]


35. if cryptomath.gcd(keyA, len(affineCipher.SYMBOLS)) != 1:


36. continue


37. 
    


38. decryptedText = affineCipher.decryptMessage(key, message)


39. if not SILENT_MODE:


40. print('Tried Key %s... (%s)' % (key, decryptedText[:40]))


41. 
    


42. if detectEnglish.isEnglish(decryptedText):


43. 
    

    Check with the user if the decrypted key has been found.

    
    


44. print()


45. print('Possible encryption hack:')


46. print('Key: %s' % (key))


47. print('Decrypted message: ' + decryptedText[:200])


48. print()


49. print('Enter D for done, or just press Enter to continue
    hacking:')


50. response = input('> ')


51.