320 http://inventwithpython.com/hacking

Email questions to the author: [email protected]

18. def hackVigenere(ciphertext):


19. fo = open('dictionary.txt')


20. words = fo.readlines()


21. fo.close()


22. 
    


23. for word in words:


24. word = word.strip() # remove the newline at the end


25. decryptedText = vigenereCipher.decryptMessage(word, ciphertext)


26. if detectEnglish.isEnglish(decryptedText, wordPercentage=40):


27. 
    

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

    
    


28. print()


29. print('Possible encryption break:')


30. print('Key ' + str(word) + ': ' + decryptedText[:100])


31. print()


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


33. response = input('> ')


34. 
    


35. if response.upper().startswith('D'):


36. return decryptedText


37. 
    


38. if name == 'main':


39. main()

Sample Run of the Vigenère Dictionary Hacker Program

When you run this program the output will look like this:

Possible encryption break:
Key ASTROLOGY: The recl yecrets crk not the qnks I tell.

Enter D for done, or just press Enter to continue breaking:

Possible encryption break:
Key ASTRONOMY: The real secrets are not the ones I tell.

Enter D for done, or just press Enter to continue breaking:

d
Copying hacked message to clipboard:
The real secrets are not the ones I tell.

The first keyword it suggests (“ASTROLOGY”) doesn’t quite work, so the user presses Enter to
let the hacking program continue until it gets the correct decryption key (“ASTRONOMY”).