72 http://inventwithpython.com/hacking

Email questions to the author: [email protected]

35. 
    

    LETTERS or less than 0

    
    


36. if num >= len(LETTERS):


37. num = num - len(LETTERS)


38. elif num < 0:


39. num = num + len(LETTERS)


40. 
    


41. 
    

    add encrypted/decrypted number's symbol at the end of translated

    
    


42. translated = translated + LETTERS[num]


43. 
    


44. else:


45. 
    

    just add the symbol without encrypting/decrypting

    
    


46. translated = translated + symbol


47. 
    


48. 
    

    print the encrypted/decrypted string to the screen

    
    


49. print(translated)


50. 
    


51. 
    

    copy the encrypted/decrypted string to the clipboard

    
    


52. pyperclip.copy(translated)

Sample Run of the Caesar Cipher Program

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

GUVF VF ZL FRPERG ZRFFNTR.

The above text is the string 'This is my secret message.' encrypted with the Caesar
cipher with key 13. The Caesar cipher program you just ran will automatically copy this
encrypted string to the clipboard so you can paste it in an email or text file. This way you can
easily take the encrypted output from the program and send it to another person.

To decrypt, just paste this text as the new value stored in the message variable on line 7. Then
change the assignment statement on line 13 to store the string 'decrypt' in the variable mode:

caesarCipher.py

6. 
   

   the string to be encrypted/decrypted

   
   


7. message = 'GUVF VF ZL FRPERG ZRFFNTR.'


8. 
   


9. 
   

   the encryption/decryption key

   
   


10. key = 13


11. 
    


12. 
    

    tells the program to encrypt or decrypt

    
    


13. mode = 'decrypt' # set to 'encrypt' or 'decrypt'

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