Linux Security Cookbook

8.1. Encrypted Mail with Emacs

Problem

You use an Emacs mailer (vm, rmail, etc.) and want to send and receive encrypted email messages.

Solution

Use mailcrypt.el with GnuPG:

               ~/.emacs:
(load-library "mailcrypt")
(mc-setversion "gpg")

Then open a mail buffer, and use any Mailcrypt functions or variables as desired:

mc-encrypt

Encrypt the mail message in the current buffer

mc-decrypt

Decrypt the mail message in the current buffer

mc-sign

Sign the mail message in the current buffer

mc-verify

Verify the signature of the mail message in the current buffer

mc-insert-public-key

Insert your public key, in ASCII format, into the current buffer

...and many more.

Discussion

Mailcrypt is an Emacs package for encrypting, decrypting, and cryptographically signing email messages. Once you have installed mailcrypt.el in your Emacs load path, e.g., by installing it in /usr/share/emacs/site-lisp, and loaded and configured it in your ~/.emacs file:

(load-library "mailcrypt")
(mc-setversion "gpg")

compose a mail message in your favorite Emacs-based mailer. When done writing the message, invoke:

M-x mc-encrypt

(or select the Encrypt function from the Mailcrypt menu). You’ll be prompted for the recipient, whose public key must be on your GnuPG keyring:

Recipients: [e-mail]

and then asked whether you want to sign the message, which is an optional step and requires your GnuPG passphrase.

Sign the message? (y or n)

Then voilà, your message becomes GnuPG-encrypted for that recipient:

-----BEGIN PGP MESSAGE----- ...