Email Self-Defense

Step 1.a Set your email program up with your email account (if it isn't already)

Open your email program and follow the wizard that sets it up with your email account.

Step 1.b Get GnuPG by downloading GPG4Win

GPG4Win is a software package that includes GnuPG. Download and install it, choosing default options whenever asked. After it's installed, you can close any windows that it creates.

Step 1.c Install the Enigmail plugin for your email program

In your email program's menu, select Add-ons (it may be in the Tools section). Make sure Extensions is selected on the left. Do you see Enigmail? if so, skip this step.

If not, search "Enigmail" with the search bar in the upper right. You can take it from here. Restart your email program when you're done.

Step 2.a Make a keypair

In your email program's menu, select OpenPGP → Setup Wizard. You don't need to read the text in the window that pops up unless you'd like to, but it's good to read the text on the later screens of the wizard.

On the second screen, titled "Signing," select "No, I want to create per-recipient rules for emails that need to be signed."

Use the default options until you reach the screen titled "Create Key".

On the screen titled "Create Key," pick a strong password! Your password should be at least 12 characters and include at least one lower case and upper case letter and at least one number or punctuation symbol. Don't forget the password, or all this work will be wasted!

The program will take a little while to finish the next step, the "Key Creation" screen. While you wait, do something else with your computer, like watching a movie or browsing the Web. The more you use the computer at this point, the faster the key creation will go.

When the OpenPGP Confirm screen pops up, select Generate Certificate and choose to save it in a safe place on your computer (we recommend making a folder called "Revocation Certificate" in your home folder and keeping it there. You'll learn more about the revocation certificate in Section 5. The setup wizard will ask you to move it onto an external device, but that isn't necessary at this moment.

Step 2.b Upload your public key to a keyserver

In your email program's menu, select OpenPGP → Key Management.

Right click on your key and select Upload Public Keys to Keyserver. Use the default keyserver in the popup.

Now someone who wants to send you an encrypted message can download your public key from the Internet. There are multiple keyservers that you can select from the menu when you upload, but they are all copies of each other, so it doesn't matter which one you use. However, it sometimes takes a few hours for them to match each other when a new key is uploaded.

GnuPG, OpenPGP, what?

You're using a program called GnuPG, but the menu in your email program is called OpenPGP. Confusing, right? In general, the terms GnuPG, GPG, GNU Privacy Guard, OpenPGP and PGP are used interchangeably, though they all have slightly different meanings.

Step 3.a Send Adele your public key

This is a special step that you won't have to do when corresponding with real people. In your email program's menu, go to OpenPGP → Key Management. You should see your key in the list that pops up. Right click on your key and select Send Public Keys by Email. This will create a new draft message, as if you had just hit the Write button.

Address the message to adele-en@gnupp.de. Put at least one word (whatever you want) in the subject and body of the email, then hit send.

It may take two or three minutes for Adele to respond. In the meantime, you might want to skip ahead and check out the Use it Well section of this guide. Once she's responded, head to the next step. From here on, you'll be doing just the same thing as when corresponding with a real person.

Step 3.b Send a test encrypted email

Write a new email in your email program, addressed to adele-en@gnupp.de. Make the subject "Encryption test" or something similar and write something in the body. Don't send it yet.

Click the icon of the key in the bottom right of the composition window (it should turn yellow). This tells Enigmail to encrypt the email with the key you downloaded in the last step.

Next to the key, you'll notice an icon of a pencil. Clicking this tells Enigmail to add a special, uniqe signature to your message, generated using your private key. This is a separate feature from encryption, and you don't have to use it for this guide.

Click Send. Enigmail will pop up a window that says "Recipients not valid, not trusted or not found."

To encrypt and email to Adele, you need her public key, and so now you'll have Enigmail download it from a keyserver. Click Download Missing Keys and use the default in the pop-up that asks you to choose a keyserver. Once it finds keys, check the first one (Key ID starting with 9), then select ok. Select ok in the next pop-up.

Now you are back at the "Recipients not valid, not trusted or not found" screen. Select Adele's key from the list and click Ok. If the message doesn't send automatically, you can hit send now.

Important: Security tips

Even if you encrypted your email, the subject line is not encrypted, so don't put private information there. The sending and receiving addresses aren't encrypted either, so they could be read by a surveillance system. When you send attachments, Enigmail will give you an option of whether you want to encrypt them.

It's also good practice to click the key icon in your email composition window before you start to write. Otherwise, your email client could save an unencrypted draft on the mail server, potentially exposing it to snooping.

Step 3.c Receive a response

When Adele receives your email, she will use her private key to decrypt it, then fetch your public key from a keyserver and use it to encrypt a response to you.

Since you encrypted this email with Adele's public key, Adele's private key is required to decrypt it. Adele is the only one with her private key, so no one except her — not even you — can decrypt it.

It may take two or three minutes for Adele to respond. In the meantime, you might want to skip ahead and check out the Use it Well section of this guide.

When you receive Adele's email and open it, Enigmail will automatically detect that it is encrypted with your public key, and then it will use your private key to decrypt it.

Notice the bar that Enigmail shows you above the message, with information about the status of Adele's key.

Passo 4.a Assine uma chave

No menu do seu programa de e-mail, vá para @@OpenPGP → Key Management@@.

Dê dois cliques na chave pública de Adele e selecione @@Select Key@@ do menu de contexto.

Na janela que aparece, selecione "@@I will not answer@@" e clique em OK.

No menu do seu programa de e-mail, vá para @@OpenPGP → Key Management → Keyserver → Upload Public Keys@@ e clique em OK.

Você efetivamente disse "Eu confio que a chave pública de Adele pertence mesmo a Adele." Isso não significa muito porque Adele não é uma pessoa de verdade, mas é uma boa prática.

Importante: cheque a identidade das pessoas antes de assinar as chaves delas

Antes de assinar a chave de uma pessoa de verdade, sempre tenha certeza de que ela pertence mesmo a quem diz, e que elas são quem dizem ser. Peça a elas pra mostrar seus ID's (a não ser que confie muito nelas) e a impressão digital de suas chaves públicas -- não somente o ID da chave pública mais curto, que pode se referir a mais de uma chave. No Enigmail, responda honestamente a janela que aparece e pergunta "@@How carefully have you verified that the key you are about to sign actually belongs to the person(s) named above?@@.

Quando devo codificar?

Quanto mais você puder codificar suas mensagens, melhor. Isso porque se você só codificar e-mails ocasionalmente, cada mensagem codificada pode despertar suspeitas em sistemas de vigilância. Se todos os quase todos os seus e-mails são codificados, as pessoas que conduzem a vigilância não saberão por onde começar.

Não queremos dizer que codificar só uma parte do seus e-mails não ajuda -- é um ótimo começo e torna a vigilância em massa mais difícil.

Importante: Cuidado com chaves inválidas

O GnuPG torna o e-mail mais seguro, mas ainda é importante estar atento para chaves inválidas, que podem ter caído em mãos erradas. E-mails codificados com chaves inválidas podem ser lidos por programas de vigilância.

Em seu programa de e-mail, volte à segunda mensagem que Adele mandou. Como Adele o codificou com a sua chave pública, vai haver uma mensagem do OpenPGP no topo, que provavelmente diz "@@OpenPGP: Part of this message encrypted.@@"

Quando usar o GnuPG, torne prestar atenção nessa barra um hábito. O programa vai te alertar por ali se você receber um e-mail codificado com uma chave na qual não se pode confiar.

Copie seu certificado de revogação para algum lugar seguro

Lembra quando você criou suas chaves e salvou o certificado de revogação que o GnuPG fez? É hora de copiar esse certificado para o armazenamento digital mais seguro que você tiver -- o ideal é um pendrive, CD ou HD guardados em um local seguro na sua casa.

Se um dia você perder sua chave privada, ou se a roubarem, você vai precisar desse arquivo de certificado.

Importante: aja rápido se alguém pegar sua chave privada

Se você perder sua chave privada ou se alguém tomar posse dela (por exemplo, roubando ou invadindo seu computador), é importante revogá-la imediatamente antes que alguém a use para ler suas mensagens encriptadas. Esse guia não cobre os passos pra revogar uma chave, mas você pode seguir as instruções no site do GnuPG. Depois que tiver , mande um e-mail pra todas as pessoas com as quais você costuma usar sua chave pra ter certeza de que elas saberão disso.