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The Mailcrypt program and this documentation are published as free software. You may redistribute and/or modify them 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.

Mailcrypt 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, 675 Mass Ave, Cambridge, MA 02139, USA.

Introduction

Mailcrypt is an Emacs Lisp package which provides a simple but powerful interface to cryptographic functions for mail and news. With Mailcrypt, encryption becomes a seamlessly integrated part of your mail and news handling environment.

This manual is long because it is complete. All of the information you need to get started is contained in this Introduction alone.

Prerequisites

Mailcrypt requires version 19 of GNU Emacs. Mailcrypt has been tested on a variety of systems under both FSF Emacs and XEmacs.

Mailcrypt requires Pretty Good (tm) Privacy, usually known as PGP. This document assumes that you have already obtained and installed PGP and that you are familiar with its basic functions. The best way to become familiar with these functions is to read the PGP User's Guide, at least Volume I.

For more information on obtaining and installing PGP, refer to the MIT PGP home page at http://web.mit.edu/network/pgp.html.

Although Mailcrypt may be used to process data in arbitrary Emacs buffers, it is most useful in conjunction with other Emacs packages for handling mail and news. Mailcrypt has specialized support for Rmail (see section `Reading Mail with Rmail' in The GNU Emacs Manual), VM (see section `Introduction' in The VM User's Manual), MH-E, and Gnus (see section `Overview' in The Gnus Manual). Information on the general use of these packages is beyond the scope of this manual.

Installation

If Mailcrypt is not installed on your system, obtain the latest version from the Mailcrypt home page at http://cag-www.lcs.mit.edu/mailcrypt/ and follow the instructions in the file `INSTALL'.

Next, teach your Emacs how and when to load the Mailcrypt functions and install the Mailcrypt key bindings. Almost all Emacs major modes (including mail and news handling modes) have corresponding "hook" variables which hold functions to be run when the mode is entered. All you have to do is add the Mailcrypt installer functions to the appropriate hooks; then the installer functions will add the Mailcrypt key bindings when the respective mode is entered.

Specifically, begin by placing the following lines into your `.emacs' file (or the system-wide `default.el' file):

(autoload 'mc-install-write-mode "mailcrypt" nil t)
(autoload 'mc-install-read-mode "mailcrypt" nil t)
(add-hook 'mail-mode-hook 'mc-install-write-mode)

Then add additional lines for your own mail and news packages as described below.

Hooking into Rmail

To hook Mailcrypt into Rmail, use the following lines:

(add-hook 'rmail-mode-hook 'mc-install-read-mode)
(add-hook 'rmail-summary-mode-hook 'mc-install-read-mode)

Hooking into VM

To hook Mailcrypt into VM, use the following lines:

(add-hook 'vm-mode-hook 'mc-install-read-mode)
(add-hook 'vm-summary-mode-hook 'mc-install-read-mode)
(add-hook 'vm-virtual-mode-hook 'mc-install-read-mode)
(add-hook 'vm-mail-mode-hook 'mc-install-write-mode)

Hooking into MH-E

To hook Mailcrypt into MH-E, use the following lines:

(add-hook 'mh-folder-mode-hook 'mc-install-read-mode)
(add-hook 'mh-letter-mode-hook 'mc-install-write-mode)

Hooking into Gnus

To hook Mailcrypt into Gnus, use the following lines:

(add-hook 'gnus-summary-mode-hook 'mc-install-read-mode)
(add-hook 'news-reply-mode-hook 'mc-install-write-mode)

Command Overview

All Mailcrypt commands are (by default) activated by three-character key sequences which begin with C-c /. The four most common operations are:

Encrypting a Message: C-c / e encrypts a message using the recipient's (or recipients') public key(s). See section Encrypting a Message.
Decrypting a Message: C-c / d decrypts a message using your secret key. See section Decrypting a message.
Signing a Message: C-c / s clearsigns a message using your secret key. See section Signing a Message.
Verifying a Signature: C-c / v verifies the signature on a clearsigned message using the sender's public key. See section Verifying a Signature.

These functions and others are documented in detail in the following chapters.

Any time you are composing or reading mail or news, you can get a summary of the available commands by typing C-h m. If you are running Emacs under X, an even easier way to see the available commands is to access the Mailcrypt pull-down menu.

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