Update Copyright header.

[elisp/flim.git] / hmac-def.el

diff --git a/hmac-def.el b/hmac-def.el
index cc59fef..264bdac 100644 (file)
--- a/hmac-def.el
+++ b/hmac-def.el
@@ -1,10 +1,12 @@
-;;; hmac-def.el --- Functions/macros for defining HMAC functions.
+;;; hmac-def.el --- A macro for defining HMAC functions.
 
-;; Copyright (C) 1999 Shuhei KOBAYASHI
+;; Copyright (C) 1999, 2001  Free Software Foundation, Inc.
 
 ;; Author: Shuhei KOBAYASHI <shuhei@aqua.ocn.ne.jp>
 ;; Keywords: HMAC, RFC 2104
 
+;; This file is part of FLIM (Faithful Library about Internet Message).
+
 ;; This program is free software; you can redistribute it and/or
 ;; modify it under the terms of the GNU General Public License as
 ;; published by the Free Software Foundation; either version 2, or
@@ -22,71 +24,62 @@
 
 ;;; Commentary:
 
-;; See RFC 2104, "HMAC: Keyed-Hashing for Message Authentication"
-;; for definition of HMAC.
+;; This program is implemented from RFC 2104,
+;; "HMAC: Keyed-Hashing for Message Authentication".
 
 ;;; Code:
 
-(require 'hmac-util)
-
-(defmacro hmac-unhex-string-macro (string length)
-  (let* ((len (eval length))
-         (dst (make-string (/ len 2) 0)))
-    `(let ((str ,string)
-           (dst ,dst)
-           (idx 0)(pos 0))
-       (while (< pos ,len)
-        (aset dst idx (+ (* (hmac-hex-to-int (aref str pos)) 16)
-                         (hmac-hex-to-int (aref str (1+ pos)))))
-        (setq idx (1+ idx)
-              pos (+ 2 pos)))
-       dst)))
-
-;; Note that H, B, and L will be evaluated multiple times.  They are
-;; usually constants, so I don't want to bother to bind them locally.
 (defmacro define-hmac-function (name H B L &optional bit)
-  "Define a function NAME which computes HMAC with hash function H.
+  "Define a function NAME(TEXT KEY) which computes HMAC with function H.
 
-HMAC function is H\(KEY XOR opad, H\(KEY XOR ipad, TEXT\)\):
+HMAC function is H(KEY XOR opad, H(KEY XOR ipad, TEXT)):
 
 H is a cryptographic hash function, such as SHA1 and MD5, which takes
-a string and return a digest of it \(in hexadecimal form\).
-B is a byte-length of a block size of H. \(B=64 for both SHA1 and MD5.\)
-L is a byte-length of hash outputs. \(L=16 for MD5, L=20 for SHA1.\)
+a string and return a digest of it (in binary form).
+B is a byte-length of a block size of H. (B=64 for both SHA1 and MD5.)
+L is a byte-length of hash outputs. (L=16 for MD5, L=20 for SHA1.)
 If BIT is non-nil, truncate output to specified bits."
-  `(defun ,name (text key)
-     ,(concat "Compute " (upcase (symbol-name name)) " over TEXT with KEY.")
-     (let ((key-xor-ipad (make-string ,B ?\x36))
-           (key-xor-opad (make-string ,B ?\x5C))
-           (len (length key))
-           (pos 0))
-       (when (> len ,B)
-         (setq key (hmac-unhex-string-macro (,H key) ,(* L 2)))
-        (setq len ,L))
-       (while (< pos len)
-         (aset key-xor-ipad pos (logxor (aref key pos) ?\x36))
-         (aset key-xor-opad pos (logxor (aref key pos) ?\x5C))
-         (setq pos (1+ pos)))
-       ;; If outer `hmac-unhex-string-macro' is removed, return value
-       ;; will be in hexadecimal form.  It is useful for test.
-       ,(if (and bit (< (/ bit 8) L))
-           `(substring
-             (hmac-unhex-string-macro
-              (,H
-               (concat key-xor-opad
-                       (hmac-unhex-string-macro
-                        (,H (concat key-xor-ipad text))
-                        ,(* L 2))))
-              ,(* L 2))
-             0 ,(/ bit 8))
-         `(hmac-unhex-string-macro
-           (,H
-            (concat key-xor-opad
-                    (hmac-unhex-string-macro
-                     (,H (concat key-xor-ipad text))
-                     ,(* L 2))))
-           ,(* L 2))))))
+  (` (defun (, name) (text key)
+       (, (concat "Compute "
+                 (upcase (symbol-name name))
+                 " over TEXT with KEY."))
+       (let ((key-xor-ipad (make-string (, B) ?\x36))
+            (key-xor-opad (make-string (, B) ?\x5C))
+            (len (length key))
+            (pos 0))
+        (unwind-protect
+            (progn
+              ;; if `key' is longer than the block size, apply hash function
+              ;; to `key' and use the result as a real `key'.
+              (if (> len (, B))
+                  (setq key ((, H) key)
+                        len (, L)))
+              (while (< pos len)
+                (aset key-xor-ipad pos (logxor (aref key pos) ?\x36))
+                (aset key-xor-opad pos (logxor (aref key pos) ?\x5C))
+                (setq pos (1+ pos)))
+              (setq key-xor-ipad (unwind-protect
+                                     (concat key-xor-ipad text)
+                                   (fillarray key-xor-ipad 0))
+                    key-xor-ipad (unwind-protect
+                                     ((, H) key-xor-ipad)
+                                   (fillarray key-xor-ipad 0))
+                    key-xor-opad (unwind-protect
+                                     (concat key-xor-opad key-xor-ipad)
+                                   (fillarray key-xor-opad 0))
+                    key-xor-opad (unwind-protect
+                                     ((, H) key-xor-opad)
+                                   (fillarray key-xor-opad 0)))
+              ;; now `key-xor-opad' contains
+              ;; H(KEY XOR opad, H(KEY XOR ipad, TEXT)).
+              (, (if (and bit (< (/ bit 8) L))
+                     (` (substring key-xor-opad 0 (, (/ bit 8))))
+                   ;; return a copy of `key-xor-opad'.
+                   (` (concat key-xor-opad)))))
+          ;; cleanup.
+          (fillarray key-xor-ipad 0)
+          (fillarray key-xor-opad 0))))))
 
 (provide 'hmac-def)
 
-;;; hmac-def.el ends here.
+;;; hmac-def.el ends here