foo.clj

(defn base32enc
  "Returns a base32 encoded strings of the byte vector

  A base32 character can represent 5 bits. We split the vector
  into chunks of 5 bytes = 40 bits = 8 * 5 bits and create a 40 bit
  Long representation of the 5 bytes. We then use Long/toString to
  get the 8 characters base32 representation.
  "
  ([vec]
     (base32enc vec *base32-alpha*))
  ([vec alpha]
     (mapcat
      (fn [coll]
	(let [res (reduce
		   #(bit-or (bit-shift-left %1 8) %2)			
		   (map #(bit-and 0xff %) coll))]
	  (loop [bitcount (* 8 (count vec))
		 s ""
		 res res]
	    (if (<= bitcount 0) s
		(recur (- bitcount 5) ; rebind bitcount
		       (str (get alpha (bit-and res 0x1f)) s)
		       (bit-shift-right res 5))))))
      (partition-all 5 vec))))