Encryption is an ancient method of changing readable text to unreadable text that dates back to Egyptian times. Encryption takes the statement "Evolution" and turns it into something which cannot be read without help through decryption. Kevin orders an Evolution t-shirt from Ximian, Inc. over the internet. He puts in his credit card number which is 1234-567-8901. For security, his computer encrypts the credit card number so it can be safely transmitted over the internet. The number now is @#$23ui7yr87#@!48970fsd, which holds no intentional resemblance to the inital number. When the information gets to Ximian, Inc. it'll be decrypted into the inital number. Encryption can be used in email in two ways: to verify that the sender is the real sender, and to hide the message while in transmission. Evolution has the capability to do both. First, you need to create a PGP key. To do this, you'll need GPG installed. This manual covers version 1.0.6 of GPG. If your version is different, this may not be entirely accurate. You may find out your version number by typing in: gpg --version. You can start by typing in: gpg --gen-key. At the first question, select 1. The next question asks you about key length. The longer the key, more stronger it is. However, the longer the key, the longer it takes to generate. This is your choice. However, 1024 bits (default) should be adequate. The next question asks you if you want your key to expire. Expiring keys make your key invalid after a certain amount of time, so old keys don't float around active. This is the same concept as a coupon at a supermarket. Next, you'll type in your Real name, your email address, and a comment. You should not forge this information, as it is used later to verify who you are. Assuming that all your information is correct, press "O" to continue. GPG now asks you for a passphrase. This is a password which you will need to decrypt and encrypt messages. This can be any length, with any characters in it. It is case sensitive, which means that it does know the difference between capital letters and lower-case. Now your key is generated. It is recommend you surf the internet, read your email, or write a letter in a word processor. This help creates randomness in the key. Once this is completed, you'll be dropped back to the command line. Now you can view your key information by typing gpg --list-keys. You should see something similar to this: /home/bob/.gnupg/pubring.gpg ---------------------------- pub 1024D/32j38dk2 2001-06-20 bob <bob@bob.com> sub 1024g/289sklj3 2001-06-20 [expires: 2002-11-14] You'll now need to upload your public key to a keyserver, so that your friends can use your key. You'll need to know the ID of your key, which is after the 1024D on the line beginning with pub. For this example, it is 32j38dk2. You now type in gpg --send-keys --keyserver wwwkeys.pgp.net 32j38dk2. Substitute your key ID for 32j38dk2. You will be prompted to type in your password and your key will be uploaded for your friends to download. You'll need to open Tools Mail Settings Once there, select the account you'd like to associate the key to and click the Edit button. In the Security tab is a section labeled Pretty Goog Privacy. Enter your key ID and click OK. Your key is now integrated into your identity in Evolution. You can either sign or encrypt a message. When you sign a message, verify that you were the one who sent it, and that no one is forging your identity. Encrypting a message makes it impossible for someone with prying eyes to view it while it's in tranmission. To sign a message, you simply click Security PGP Sign . You will be prompted for your PGP password. Once you enter it, click OK and your message will be signed. Encrypting a message is very similar to signing a message. You simply click the menu item Security PGP Encrypt Sometimes, a friend will send you a message which is encrypted. In order for you to read it, you need to unencrypt it. When you view the encrypted message, Evolution will prompt you for your PGP password. You type in your PGP password and the message is then decrypted.