With Enigmail, you can easily sign and/or encrypt your emails (including attachments). However, Enigmail is only available as a plug-in for Thunderbird and Seamonkey and requires the installation of GnuPG (http://www.gnupg.org/) or Gpg4Win (http://www.gpg4win.org/). Here’s a quick guide on how to set up encryption in 5 minutes.
Before you begin: This tutorial assumes that you already have a working version of Thunderbird (at least version 2) installed. This tutorial also only covers setup on Windows (personally tested only with Win7 Ultimate). For other platforms, the specifics are mostly limited to the installation of GnuPG/Gpg4Win, so it should not be difficult to use these instructions for macOS X or Linux. The English documentation can be found here: http://enigmail.mozdev.org/documentation/quickstart-ch1.php.html#id2487302. Although the official documentation recommends installing GnuPG, these instructions focus on using Gpg4Win.
- Step 1: Install Gpg4Win.
First, download Gpg4Win and install the software. During installation, simply accept the default options and paths. A computer restart is required afterward. - Step 2: Create a key pair with Kleopatra.
Gpg4Win includes several tools to allow for numerous individual customizations. Now, start Kleopatra – it should appear in the Windows Start menu; otherwise, you can find it under “All Programs” > “Gpg4Win” > “Kleopatra.”
To create a key pair, first click “File” > “New Certificate,” and then “Create Personal Open-PGP Key Pair.” If you wish to choose the encryption method yourself, click “Advanced Settings.”- Step 2a: Advanced Settings. Define the encryption method, certificate usage, and validity period. Both RSA and DSA (+Elgamal) methods offered are good; however, DSA is often generally recommended. Leave the checkboxes as suggested, for signing and encrypting. A runtime of 2 years, as suggested, is a good choice.
Now click “Next” and finally “Create Key.” You will then need to enter a passphrase, which is simply a password. Choose something complex, yet memorable. Combinations of lowercase and uppercase letters, numbers, and special characters are best. Your passphrase should be at least 8 characters long.
- Step 2b: Store public keys on keys.gnupg.net. You can only store your public key on the community server, which is important for communication partners who can then verify your identity. Information on how the chain of trust for the desired identity is built can also be found there, if applicable.
- Step 3: Install the Enigmail Add-On.
Go to “Tools” > “Add-ons” to access Thunderbird’s Add-on Manager page. In the search field at the top, type “Enigmail,” select the appropriate search result, and then follow the installation instructions.- Step 3a: Configure Enigmail. The default settings are generally fine. If you enable expert mode, all available options will appear, arranged in different tabs. There, you can, for example, define the passphrase cache time, and much more.
A restart of Thunderbird is required to complete the installation or to activate Enigmail.
- Step 4: Sign and/or encrypt emails.
In the new email composition window, you can simply choose whether to sign or encrypt. To do this, just select the corresponding line in the “OpenPGP” menu. Otherwise, everything remains the same. The add-on will now indicate whether the email has been signed or encrypted, and whether the identity is genuine or not. Information about the public key can also be displayed.
If you wish, you can now also back up the complete key pair (e.g., to a USB stick) or send the public key to acquaintances.
It is always possible to make adjustments later. In Thunderbird, there is an “OpenPGP” menu under which numerous options are available.
Important note: Enigmail still has some issues with emails written in HTML. It is advised to change the email composition in Thunderbird to plain text. To do this, simply go to “Tools” > “Account Settings” > “Composition Addressing” and uncheck “Compose messages in HTML format.”
Mozilla Project Homepage: https://addons.mozilla.org/de/thunderbird/addon/enigmail/
English documentation for Gpg4Win: http://www.gpg4win.org/doc/en/gpg4win-compendium_11.html