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1(ns compojure.crypto
2  "Functions for cryptographically signing, verifying and encrypting data."
3  (:use compojure.encodings)
4  (:use clojure.contrib.def)
5  (:use clojure.contrib.java-utils)
6  (:import java.security.SecureRandom)
7  (:import javax.crypto.Cipher)
8  (:import javax.crypto.KeyGenerator)
9  (:import javax.crypto.Mac)
10  (:import javax.crypto.spec.SecretKeySpec)
11  (:import javax.crypto.spec.IvParameterSpec)
12  (:import java.util.UUID))
13
14(defvar hmac-defaults
15  {:algorithm "HmacSHA256"}
16  "Default options for HMACs.")
17
18(defvar encrypt-defaults
19  {:algorithm  "AES"
20   :key-size   128
21   :mode       "CBC"
22   :padding    "PKCS5Padding"}
23  "Default options for symmetric encryption.")
24
25(defn- make-algorithm
26  "Return an algorithm string suitable for JCE from a map of options."
27  [options]
28  (str "AES/" (options :mode) "/" (options :padding)))
29
30(defn- make-cipher
31  "Create an AES Cipher instance."
32  [options]
33  (Cipher/getInstance (make-algorithm options)))
34
35(defn decrypt-bytes
36  "Decrypts a byte array with the given key and encryption options."
37  [options key data]
38  (let [options    (merge encrypt-defaults options)
39        cipher     (make-cipher options)
40        [iv data]  (split-at (.getBlockSize cipher) data)
41        iv-spec    (IvParameterSpec. (to-bytes iv))
42        secret-key (SecretKeySpec. key (options :algorithm))]
43    (.init cipher Cipher/DECRYPT_MODE secret-key iv-spec)
44    (.doFinal cipher (to-bytes data))))
45
46(defn decrypt
47  "Base64 encodes and encrypts a string with the given key and algorithm."
48  [options key data]
49  (String. (decrypt-bytes options key (base64-decode-bytes data))))