;;; rfc2104.el --- RFC2104 Hashed Message Authentication Codes
-;; Copyright (C) 1998, 1999, 2000, 2001, 2002, 2003, 2004,
-;; 2005, 2006, 2007, 2008 Free Software Foundation, Inc.
+;; Copyright (C) 1998-2012 Free Software Foundation, Inc.
;; Author: Simon Josefsson <jas@pdc.kth.se>
;; Keywords: mail
;;; Commentary:
-;; This is a quick'n'dirty, low performance, implementation of RFC2104.
+;; This is a high performance implementation of RFC2104.
;;
;; Example:
;;
;; (rfc2104-hash 'md5 64 16 "Jefe" "what do ya want for nothing?")
;; "750c783e6ab0b503eaa86e310a5db738"
;;
-;; (require 'sha-1)
-;; (rfc2104-hash 'sha1-encode 64 20 "Jefe" "what do ya want for nothing?")
+;; (require 'sha1)
+;; (rfc2104-hash 'sha1 64 20 "Jefe" "what do ya want for nothing?")
;; "effcdf6ae5eb2fa2d27416d5f184df9c259a7c79"
;;
;; 64 is block length of hash function (64 for MD5 and SHA), 16 is
;; 2000-08-15 `rfc2104-hexstring-to-bitstring'
;; 2000-05-12 added sha-1 example, added test case reference
;; 2003-11-13 change rfc2104-hexstring-to-bitstring to ...-byte-list
+;; 2008-04-25 rewrite rfc2104-hash for speed
;;; Code:
;; Magic character for outer HMAC round. 0x5C == 92 == '\'
(defconst rfc2104-opad ?\x5C)
-;; Not so magic character for padding the key. 0x00
-(defconst rfc2104-zero ?\x00)
-
-;; Alist for converting hex to decimal.
-(defconst rfc2104-hex-alist
- '((?0 . 0) (?a . 10) (?A . 10)
- (?1 . 1) (?b . 11) (?B . 11)
- (?2 . 2) (?c . 12) (?C . 12)
- (?3 . 3) (?d . 13) (?D . 13)
- (?4 . 4) (?e . 14) (?E . 14)
- (?5 . 5) (?f . 15) (?F . 15)
- (?6 . 6)
- (?7 . 7)
- (?8 . 8)
- (?9 . 9)))
-
-(defun rfc2104-hex-to-int (str)
- (if str
- (if (listp str)
- (+ (* 16 (rfc2104-hex-to-int (cdr str)))
- (cdr (assoc (car str) rfc2104-hex-alist)))
- (rfc2104-hex-to-int (reverse (append str nil))))
- 0))
-
-(defun rfc2104-hexstring-to-bitstring (str)
- (let (out)
- (while (< 0 (length str))
- (push (rfc2104-hex-to-int (substring str -2)) out)
- (setq str (substring str 0 -2)))
- (apply (if (fboundp 'unibyte-string) 'unibyte-string 'string) out)))
+(defconst rfc2104-nybbles
+ (let ((v (make-vector
+ ;; Find upper bound to save some space.
+ (1+ (max ?0 ?9 ?a ?f ?A ?F))
+ ;; Use non-numeric default to catch bogus hex strings.
+ nil))
+ (ls '((?0 . 0) (?a . 10) (?A . 10)
+ (?1 . 1) (?b . 11) (?B . 11)
+ (?2 . 2) (?c . 12) (?C . 12)
+ (?3 . 3) (?d . 13) (?D . 13)
+ (?4 . 4) (?e . 14) (?E . 14)
+ (?5 . 5) (?f . 15) (?F . 15)
+ (?6 . 6)
+ (?7 . 7)
+ (?8 . 8)
+ (?9 . 9))))
+ (while ls
+ (aset v (caar ls) (cdar ls))
+ (setq ls (cdr ls)))
+ v))
+
+(eval-when-compile
+ (defmacro rfc2104-string-make-unibyte (string)
+ "Return the unibyte equivalent of STRING.
+In XEmacs return just STRING."
+ (if (featurep 'xemacs)
+ string
+ `(string-make-unibyte ,string))))
(defun rfc2104-hash (hash block-length hash-length key text)
(let* (;; if key is longer than B, reset it to HASH(key)
(key (if (> (length key) block-length)
(funcall hash key) key))
- (k_ipad (append key nil))
- (k_opad (append key nil)))
- ;; zero pad k_ipad/k_opad
- (while (< (length k_ipad) block-length)
- (setq k_ipad (append k_ipad (list rfc2104-zero))))
- (while (< (length k_opad) block-length)
- (setq k_opad (append k_opad (list rfc2104-zero))))
- ;; XOR key with ipad/opad into k_ipad/k_opad
- (setq k_ipad (mapcar (lambda (c) (logxor c rfc2104-ipad)) k_ipad))
- (setq k_opad (mapcar (lambda (c) (logxor c rfc2104-opad)) k_opad))
- ;; perform outer hash
- (funcall hash (concat k_opad (rfc2104-hexstring-to-bitstring
- ;; perform inner hash
- (funcall hash (concat k_ipad text)))))))
+ (len (length key))
+ (ipad (make-string block-length rfc2104-ipad))
+ (opad (make-string (+ block-length hash-length) rfc2104-opad))
+ c partial)
+ ;; Prefix *pad with key, appropriately XORed.
+ (do ((i 0 (1+ i)))
+ ((= len i))
+ (setq c (aref key i))
+ (aset ipad i (logxor rfc2104-ipad c))
+ (aset opad i (logxor rfc2104-opad c)))
+ ;; Perform inner hash.
+ (setq partial (rfc2104-string-make-unibyte
+ (funcall hash (concat ipad text))))
+ ;; Pack latter part of opad.
+ (do ((r 0 (+ 2 r))
+ (w block-length (1+ w)))
+ ((= (* 2 hash-length) r))
+ (aset opad w
+ (+ (* 16 (aref rfc2104-nybbles (aref partial r)))
+ ( aref rfc2104-nybbles (aref partial (1+ r))))))
+ ;; Perform outer hash.
+ (rfc2104-string-make-unibyte (funcall hash opad))))
(provide 'rfc2104)
-;; arch-tag: cf671d5c-a45f-4a09-815e-704e59e43950
;;; rfc2104.el ends here
projects / gnus / blobdiff