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[gnus] / contrib / gpg.el

;;; gpg.el --- Interface to GNU Privacy Guard

;; Copyright (C) 2000 RUS-CERT, University Of Stuttgart

;; Author: Florian Weimer <Florian.Weimer@RUS.Uni-Stuttgart.DE>
;; Maintainer: Florian Weimer <Florian.Weimer@RUS.Uni-Stuttgart.DE>
;; Keywords: crypto
;; Created: 2000-04-15

;; $Id: gpg.el,v 1.18 2002/01/25 18:00:44 huber Exp $

;; This file is NOT (yet?) 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 2, 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; see the file COPYING.  If not, write to the
;; Free Software Foundation, Inc., 59 Temple Place - Suite 330,
;; Boston, MA 02111-1307, USA.

;;; Commentary:

;; ALPHA ALPHA ALPHA ALPHA ALPHA ALPHA ALPHA ALPHA ALPHA ALPHA ALPHA
;; ALPHA ALPHA ALPHA ALPHA ALPHA ALPHA ALPHA ALPHA ALPHA ALPHA ALPHA
;;
;; This code is not well-tested.  BE CAREFUL!
;; 
;; ALPHA ALPHA ALPHA ALPHA ALPHA ALPHA ALPHA ALPHA ALPHA ALPHA ALPHA
;; ALPHA ALPHA ALPHA ALPHA ALPHA ALPHA ALPHA ALPHA ALPHA ALPHA ALPHA

;; Implemented features which can be tested:
;;
;; * Customization for all flavors of PGP is possible.
;; * The main operations (verify, decrypt, sign, encrypt, sign &
;;   encrypt) are implemented.
;; * Optionally, Gero Treuner's gpg-2comp script is supported, 
;;   to generate data which is compatible with PGP 2.6.3.

;; Customizing external programs 
;; =============================

;; The customization are very similar to those of others programs,
;; only the C-ish "%" constructs have been replaced by more Lisp-like
;; syntax.
;;
;; First, you have to adjust the default executable paths
;; (`gpg-command-default-alist', customization group `gpg-options',
;; "Controlling GnuPG invocation.").  After that, you should
;; change the configuration options which control how specific
;; command line flags are built (`gpg-command-flag-sign-with-key',
;; (`gpg-command-flag-recipient').  The elements of these lists are
;; concatenated without spaces, and a new argument is only started
;; where indicated.  The `gpg-command-flag-recipient' list is special:
;; it consists of two parts, the first one remains at the beginning
;; of the argument, the second one is repeated for each recipient.
;; Finally, `gpg-command-passphrase-env' has to be changed if there's
;; no command line flag to force the external program to read the data
;; from standard input before the message.
;;
;; In customization group `gpg-commands', "Controlling GnuPG
;; invocation.", you have to supply the actual syntax for external
;; program calls.  Each variable consists of a pair of a program
;; specification (if a Lisp symbol is given here, it is translated
;; via `gpg-command-default-alist') and a list of program arguments
;; with placeholders.  Please read the documentation of each variable
;; before making your adjustments and try to match the given
;; requirements as closely as possible!
;;
;; The `gpg-commands-key' group, "GnuPG Key Management Commands.",
;; specifies key management commands.  The syntax of these variables
;; is like those in the `gpg-commands' group.  Note that the output
;; format of some of these external programs has to match very close
;; that of GnuPG.  Additional tools (Thomas Roessler's "pgpring.c")
;; are available if your favorite implementation of OpenPGP cannot
;; output the this format.

;; Security considerations 
;; =======================

;; On a typical multiuser UNIX system, the memory image of the
;; Emacs process is not locked, therefore it can be swapped to disk
;; at any time.  As a result, the passphrase might show up in the
;; swap space (even if you don't use the passphrase cache, i.e. if
;; `gpg-passphrase-timeout' is 0).  If someone is able to run `gdb' or
;; another debugger on your Emacs process, he might be able to recover
;; the passphrase as well.  Unfortunately, nothing can be done in
;; order to prevent this at the moment.
;;
;; BE CAREFUL: If you use the passphrase cache feature, the passphrase
;; is stored in the variable `gpg-passphrase' -- and it is NOT
;; encrypted in any way.  (This is a conceptual problem because the
;; nature of the passphrase cache requires that Emacs is able to
;; decrypt automatically, so only a very weak protection could be
;; applied anyway.)
;;
;; In addition, if you use an unpatched Emacs 20 (and earlier
;; versions), passwords show up in the output of the `view-lossage'
;; function (bound to `C-h l' by default).

\f
;;; Code:

(require 'timer)
(eval-when-compile (require 'cl))

(eval-and-compile 
  (defalias 'gpg-point-at-eol
    (if (fboundp 'point-at-eol)
        'point-at-eol
      'line-end-position)))