Message Digest in Clojure

md.clj

(ns #^{:author "Jürgen Hötzel",
       :doc "Message Digest function for Clojure

  Usage
    (require 'md)

  MD5 Checksum String:
    (md/digest-str  (md/sum \"MD5\" \"/etc/passwd\"))
    \"85dbcf75fa3eb92335cc3ac47dfa64c9\""}
  md
  (:import java.security.MessageDigest
	   java.io.FileInputStream
	   java.nio.ByteBuffer))

(defn sum
  "Compute message digest of a FileInputStream"
  ([#^String file]
     (sum "MD5" file))
  ([#^String algorithm #^String file]
     (let [md (MessageDigest/getInstance algorithm)
	   bb (ByteBuffer/allocateDirect 8192)]
       (with-open [channel (.getChannel (FileInputStream. file))]
	 (while (pos? (.read  channel bb))
	   (.flip bb)
	   (.update md bb)
	   (.clear bb))
	 (.digest md)))))

(defn digest-str
  [#^bytes bytes]
  (-> (BigInteger. 1 bytes) (.toString 16)))