http://www.teamfair.info/wiki/index.php?title=Lock_to_key <-- What I'm trying to do

Lock to Key (nmDC)

(defn nibble-swap [num]
  (bit-or (bit-shift-right num 4)
	  (bit-and (bit-shift-left num 4) 240)))

(defn xor-string [s]
  (reduce bit-xor (map int (list* s))))

(defn l2 [lock]
  (let [lock-len (count lock)
	a (map #(bit-xor (int (get lock %)) (int (get lock (dec %) 0))) (range lock-len))
	b (reduce bit-xor (map int (vector (first lock) (last lock) (nth lock (- lock-len 2)) 5)))
	c (conj a b)
	d (map nibble-swap c)
	key (apply str (map char d))]
    key))