--- /dev/null
+;;; rfc2104.el --- RFC2104 Hashed Message Authentication Codes
+
+;; Copyright (C) 1998-2016 Free Software Foundation, Inc.
+
+;; Author: Simon Josefsson <jas@pdc.kth.se>
+;; Keywords: mail
+
+;; This file is part of GNU Emacs.
+
+;; GNU Emacs 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 3 of the License, or
+;; (at your option) any later version.
+
+;; GNU Emacs is distributed in the hope that it will be useful,
+;; but WITHOUT ANY WARRANTY; without even the implied warranty of
+;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+;; GNU General Public License for more details.
+
+;; You should have received a copy of the GNU General Public License
+;; along with GNU Emacs. If not, see <http://www.gnu.org/licenses/>.
+
+;;; Commentary:
+
+;; This is a high performance implementation of RFC2104.
+;;
+;; Example:
+;;
+;; (require 'md5)
+;; (rfc2104-hash 'md5 64 16 "Jefe" "what do ya want for nothing?")
+;; "750c783e6ab0b503eaa86e310a5db738"
+;;
+;; (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
+;; resulting hash length (16 for MD5, 20 for SHA).
+;;
+;; Tested with Emacs 20.2 and XEmacs 20.3.
+;;
+;; Test case reference: RFC 2202.
+
+;;; History:
+
+;; 1998-08-16 initial release posted to gnu.emacs.sources
+;; 1998-08-17 use append instead of char-list-to-string
+;; 1998-08-26 don't require hexl
+;; 1998-09-25 renamed from hmac.el to rfc2104.el, also renamed functions
+;; 1999-10-23 included in pgnus
+;; 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:
+
+(eval-when-compile (require 'cl))
+
+;; Magic character for inner HMAC round. 0x36 == 54 == '6'
+(defconst rfc2104-ipad ?\x36)
+
+;; Magic character for outer HMAC round. 0x5C == 92 == '\'
+(defconst rfc2104-opad ?\x5C)
+
+(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))
+ (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)
+
+;;; rfc2104.el ends here
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