lisp/md5.el

   1 ;;; md5.el --- MD5 message digest calculation (RFC 1321)
   2
   3 ;; Copyright (C) 2000 Free Software Foundation, Inc.
   4
   5 ;; Author: Dave Love <fx@gnu.org>
   6 ;; Keywords: mail, processes, tools
   7
   8 ;; This file is free software; you can redistribute it and/or modify
   9 ;; it under the terms of the GNU General Public License as published by
  10 ;; the Free Software Foundation; either version 2, or (at your option)
  11 ;; any later version.
  12
  13 ;; This file is distributed in the hope that it will be useful,
  14 ;; but WITHOUT ANY WARRANTY; without even the implied warranty of
  15 ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16 ;; GNU General Public License for more details.
  17
  18 ;; You should have received a copy of the GNU General Public License
  19 ;; along with GNU Emacs; see the file COPYING.  If not, write to
  20 ;; the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  21 ;; Boston, MA 02111-1307, USA.
  22
  23 ;;; Commentary:
  24
  25 ;; Provides the `md5' function for computing the MD5 `message
  26 ;; digest'/`fingerprint'/`checksum' for a string or buffer.  This is
  27 ;; compatible with the XEmacs version.  We expect to have primitive
  28 ;; MD5 support in a future version of Emacs.
  29
  30 ;; MD5 is defined in RFC 1321.
  31
  32 ;;; Code:
  33
  34 ;; Not worth customizing?  Will go away anyhow with primitive support.
  35 (defvar md5-program "md5sum"
  36   "Name of a program to calculate MD5 (message digest) checksums.
  37 This should read standard input and output the MD5 checksum in the
  38 first 32 bytes of standard output.  `md5sum' is in GNU Textutils.  An
  39 alternative is `md5', present in the SSLeay distribution.")
  40
  41 ;;;###autoload
  42 (defun md5 (object &optional start end encoding noerror)
  43   "Return the MD5 message digest (checksum or fingerprint) of OBJECT.
  44 OBJECT is a buffer or a atring.  Optional arguments START and END
  45 specify a region of the object to use, where the first character is 1
  46 for both buffers and strings.
  47
  48 Optional argument ENCODING specifies a coding system with which to
  49 encode the text for computing the digest.  If omitted, the normal
  50 rules will be used to find a coding system for output to
  51 `md5-program'.  It probably makes most sense to use unibyte data and
  52 `binary' encoding.  Optional argument NOERROR is for XEmacs
  53 compatibility and is ignored.
  54
  55 In this implementation, the program named by `md5-program' is run to
  56 do the calculation.
  57
  58 MD5 is defined in RFC 1321."
  59   (with-temp-buffer
  60     (let ((in-buffer (current-buffer))
  61           (out-buffer (current-buffer)))
  62       (if (stringp object)
  63           (insert object)
  64         (setq in-buffer object))
  65       (goto-char (point-min))
  66       (unless encoding
  67         (setq encoding coding-system-for-write))
  68       (with-current-buffer in-buffer
  69         (let ((coding-system-for-write encoding))
  70           (unless (eq 0 (call-process-region (or start (point-min))
  71                                              (or end (point-max))
  72                                              md5-program nil out-buffer))
  73             (error "Running MD5 command %s failed"
  74                    (cons md5-program md5-program-args)))))
  75       ;; The meaningful output is the first 32 characters.
  76       ;; Don't return the newline that follows them!
  77       (buffer-substring 1 33))))
  78
  79 (provide 'md5)
  80
  81 ;;; md5.el ends here