def displayMenu():
    print("1. Encrypt New Message.")
    print("2. Decrypt Message.")
    print("3. Quit.")
    print("Enter Choice: ", end="") 

def encryptMessage():
    # get plain text from user
    Plaintext = input("Enter New Message: ")
    valid = False
    # get key from user (iterate until the user has input a key that is long enough)
    while not valid:
        OneTimePad = input("Enter New Key: ")
        if len(OneTimePad) < len(Plaintext):
            print("Key is not long enough!")
        else:
            valid = True
    # apply bit-wise XOR ('^' in python) to each character of the plaintext and key
    # and build up the cipher text
    Ciphertext = ""
    for counter in range(0, len(Plaintext)):
        Ciphertext = Ciphertext + chr(ord(Plaintext[counter]) ^ ord(OneTimePad[counter]))
    print("Cipher text:", Ciphertext)
    # some of the characters may be non-printing, so output as binary to a binary file 
    # (rather than a text file)
    # The key is text (was typed in by the user) so output as text to a text file
    f1 = open("Message.txt", "wb")
    f2 = open("Key.txt", "w")
    f1.write(bytes(Ciphertext, 'utf-8'))
    f2.write(OneTimePad)
    f1.close()
    f2.close() 

# add code to this procedure to decrypt the message that is in the message.txt file
def decryptMessage():
    pass  

# code starts running here
choice = 0
while choice != 3:
    displayMenu()
    choice = int(input())
    if choice == 1:
        encryptMessage()
    if choice == 2:
        decryptMessage()