Problème avec python

#!/usr/bin/env python
# -*- coding: utf-8 -*-
message = "Ce soir, on attaque les Gaulois!"
message = message.decode("utf-8").upper()in module
key = 3
lettres = "ABCDEFGHIJKLMNOPQRSTUVWXYZ ÀÂÇÉÈÊËÎÔÛÙ"
lettres = lettres.decode("utf-8")
crypted = ""
for car in message:
    if car in lettres:
       num = lettres.find(car)
       num += key
       if num >= len(lettres):
           num = num - len(lettres)
       crypted += lettres[num]
    else:
        crypted += car
print ("\n*** Message crypté ***")
print (crypted) + "\n"