-def railfence_break(message, max_key_length=20,
- fitness=Pletters, chunksize=500):
- """Breaks a railfence cipher using a matrix of given rank and letter frequencies
-
-
- """
-
- sanitised_message = sanitise(message)
- results = starmap(worker, [(sanitised_message, i, fitness)
- for i in range(2, max_key_length+1)])
- return max(results, key=lambda k: k[1])
-
-