/usr/share/emacs/site-lisp/flim/hmac-def.el is in flim 1:1.14.9+0.20110516-1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 | ;;; hmac-def.el --- A macro for defining HMAC functions.
;; 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
;; (at your option) any later version.
;; This program 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 this program; see the file COPYING. If not, write to
;; the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
;; Boston, MA 02110-1301, USA.
;;; Commentary:
;; This program is implemented from RFC 2104,
;; "HMAC: Keyed-Hashing for Message Authentication".
;;; Code:
(defmacro define-hmac-function (name H B L &optional bit)
"Define a function NAME(TEXT KEY) which computes HMAC with function H.
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 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))
(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
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