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121 lines
3.9 KiB
EmacsLisp
121 lines
3.9 KiB
EmacsLisp
;;; rfc2104.el --- RFC2104 Hashed Message Authentication Codes
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;; Copyright (C) 1998, 1999, 2000, 2002, 2003, 2004,
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;; 2005, 2006 Free Software Foundation, Inc.
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;; Author: Simon Josefsson <jas@pdc.kth.se>
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;; Keywords: mail
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;; This file is part of GNU Emacs.
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;; GNU Emacs is free software; you can redistribute it and/or modify
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;; it under the terms of the GNU General Public License as published by
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;; the Free Software Foundation; either version 2, or (at your option)
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;; any later version.
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;; GNU Emacs is distributed in the hope that it will be useful,
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;; but WITHOUT ANY WARRANTY; without even the implied warranty of
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;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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;; GNU General Public License for more details.
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;; You should have received a copy of the GNU General Public License
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;; along with GNU Emacs; see the file COPYING. If not, write to the
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;; Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
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;; Boston, MA 02110-1301, USA.
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;;; Commentary:
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;;; This is a quick'n'dirty, low performance, implementation of RFC2104.
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;;;
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;;; Example:
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;;;
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;;; (require 'md5)
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;;; (rfc2104-hash 'md5 64 16 "Jefe" "what do ya want for nothing?")
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;;; "750c783e6ab0b503eaa86e310a5db738"
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;;;
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;;; (require 'sha-1)
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;;; (rfc2104-hash 'sha1-encode 64 20 "Jefe" "what do ya want for nothing?")
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;;; "effcdf6ae5eb2fa2d27416d5f184df9c259a7c79"
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;;;
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;;; 64 is block length of hash function (64 for MD5 and SHA), 16 is
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;;; resulting hash length (16 for MD5, 20 for SHA).
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;;;
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;;; Tested with Emacs 20.2 and XEmacs 20.3.
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;;;
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;;; Test case reference: RFC 2202.
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;;; Release history:
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;;;
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;;; 1998-08-16 initial release posted to gnu.emacs.sources
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;;; 1998-08-17 use append instead of char-list-to-string
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;;; 1998-08-26 don't require hexl
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;;; 1998-09-25 renamed from hmac.el to rfc2104.el, also renamed functions
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;;; 1999-10-23 included in pgnus
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;;; 2000-08-15 `rfc2104-hexstring-to-bitstring'
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;;; 2000-05-12 added sha-1 example, added test case reference
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;;; Code:
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(eval-when-compile (require 'cl))
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;; Magic character for inner HMAC round. 0x36 == 54 == '6'
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(defconst rfc2104-ipad ?\x36)
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;; Magic character for outer HMAC round. 0x5C == 92 == '\'
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(defconst rfc2104-opad ?\x5C)
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;; Not so magic character for padding the key. 0x00
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(defconst rfc2104-zero ?\x00)
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;; Alist for converting hex to decimal.
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(defconst rfc2104-hex-alist
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'((?0 . 0) (?a . 10) (?A . 10)
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(?1 . 1) (?b . 11) (?B . 11)
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(?2 . 2) (?c . 12) (?C . 12)
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(?3 . 3) (?d . 13) (?D . 13)
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(?4 . 4) (?e . 14) (?E . 14)
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(?5 . 5) (?f . 15) (?F . 15)
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(?6 . 6)
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(?7 . 7)
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(?8 . 8)
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(?9 . 9)))
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(defun rfc2104-hex-to-int (str)
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(if str
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(if (listp str)
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(+ (* 16 (rfc2104-hex-to-int (cdr str)))
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(cdr (assoc (car str) rfc2104-hex-alist)))
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(rfc2104-hex-to-int (reverse (append str nil))))
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0))
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(defun rfc2104-hexstring-to-bitstring (str)
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(let (out)
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(while (< 0 (length str))
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(push (rfc2104-hex-to-int (substring str -2)) out)
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(setq str (substring str 0 -2)))
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(concat out)))
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(defun rfc2104-hash (hash block-length hash-length key text)
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(let* (;; if key is longer than B, reset it to HASH(key)
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(key (if (> (length key) block-length)
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(funcall hash key) key))
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(k_ipad (append key nil))
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(k_opad (append key nil)))
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;; zero pad k_ipad/k_opad
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(while (< (length k_ipad) block-length)
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(setq k_ipad (append k_ipad (list rfc2104-zero))))
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(while (< (length k_opad) block-length)
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(setq k_opad (append k_opad (list rfc2104-zero))))
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;; XOR key with ipad/opad into k_ipad/k_opad
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(setq k_ipad (mapcar (lambda (c) (logxor c rfc2104-ipad)) k_ipad))
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(setq k_opad (mapcar (lambda (c) (logxor c rfc2104-opad)) k_opad))
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;; perform outer hash
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(funcall hash (concat k_opad (rfc2104-hexstring-to-bitstring
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;; perform inner hash
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(funcall hash (concat k_ipad text)))))))
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(provide 'rfc2104)
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;;; arch-tag: cf671d5c-a45f-4a09-815e-704e59e43950
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;;; rfc2104.el ends here
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