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Email Self-Defense

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V4.0

Email Self-Defense

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- Bulk surveillance violates our fundamental rights and makes free speech risky. This guide will teach you a basic surveillance self-defense skill: email encryption. Once you've finished, you'll be able to send and receive emails that are scrambed to make sure a surveillance agent or thief intercepting your email can't read it. All you need is a computer with an Internet connection, an email account, and about half an hour.

+ Bulk surveillance violates our fundamental rights and makes free speech risky. This guide will teach you a basic surveillance self-defense skill: email encryption. Once you've finished, you'll be able to send and receive emails that are scrambed to make sure a surveillance agent or thief intercepting your email can't read it. All you need is a computer with an Internet connection, an email account, about forty minutes and five dice (optional, but recommended).

Even if you have nothing to hide, using encryption helps protect the privacy of people you communicate with, and makes life difficult for bulk surveillance systems. If you do have something important to hide, you're in good company; these are the same tools that Edward Snowden used to share his famous secrets about the NSA.

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Step 1.a Setup your email program with your email account

Open your email program and follow the wizard (step-by-step walkthrough) that sets it up with your email account. Look for the letters SSL, TLS, or STARTTLS to the right of the servers when you're setting up your account. If you don't see them, you will still be able to use encryption, but this means that the people running your email system are running behind the industry standard in protecting your security and privacy. We recommend that you send them a friendly email asking them to enable SSL, TLS, or STARTTLS for your email server.

Troubleshooting

The wizard doesn't launch: You can launch the wizard yourself, but the menu option for doing so is named differently in each email programs. The button to launch it will be in the program's main menu, under "New" or something similar, titled something like "Add account" or "New/Existing email account."; You can launch the wizard yourself, but the menu option for doing so is named differently in each email program. The button to launch it will be in the program's main menu, under "New" or something similar, titled something like "Add account" or "New/Existing email account."
The wizard can't find my account or isn't downloading my mail: Before searching the Web, we recommend you start by asking other people who use your email system, to figure out the correct settings.
Don't see a solution to your problem?

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#2 Make your keys

To use the GnuPG system, you'll need a public key and a private key (known together as a keypair). Each is a long string of randomly generated numbers and letters that are unique to you. Your public and private keys are linked together by a special mathematical function.

Your public key isn't like a physical key, because it's stored in the open in an online directory called a keyserver. People download it and use it, along with GnuPG, to encrypt emails they send to you. You can think of the keyserver as phonebook, where people who want to send you an encrypted email look up your public key.

Your public key isn't like a physical key, because it's stored in the open in an online directory called a keyserver. People download it and use it, along with GnuPG, to encrypt emails they send to you. You can think of the keyserver as a phonebook; people who want to send you encrypted email can look up your public key.

Your private key is more like a physical key, because you keep it to yourself (on your computer). You use GnuPG and your private key to descramble encrypted emails other people send to you. In addition to encryption and decryption, you can also use these keys to sign messages and check the authenticity of other people's signatures. This process helps stop impersonators. We'll discuss this more on the next section.

Your private key is more like a physical key, because you keep it to yourself (on your computer). You use GnuPG and your private key to descramble encrypted emails other people send to you.

In addition to encryption and decryption, you can also use these keys to sign messages and check the authenticity of other people's signatures. This process helps stop impersonators. We'll discuss this more in the next section.

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Step 2.a Make a keypair

The Enigmail Setup wizard may start automatically. If it doesn't, select Enigmail → Setup Wizard from your email program's menu. 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. Click Next with the default options selected, except in these instances:

On the screen titled "Encryption," select "Encrypt all of my messages by default, because privacy is critical to me."
On the screen titled "Signing," select "Don't sign my messages by default."
On the screen titled "Key Selection," select "I want to create a new key pair for signing and encrypting my email."
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. Always assume surveillance agents can figure out your online passwords, so never reuse passwords for GnuPG elsewhere. Don't forget the password, or all this work will be wasted!
On the screen titled "Create Key," pick a strong password! We recommend the Diceware method, which creates passwords which are both strong and memorable. To use the Diceware method, you will need dice and this list of words. Do not substitute computer dice for physical dice. Notice that each word on the word list corresponds to a unique five-digit number. Roll one die five times, or five dice once, then string the numbers on the dice dice together to create a five-digit number, and then look up the corresponding word.
Repeat this process until you have at least six words, separating each with a space and keeping them all lowercase. You'll end up with a password like "dog help people drive match ice." Don't rearrange or discard the words, because doing so makes the process much less secure.
Diceware passwords are hard to remember until you've typed them in a handful of times. Write down your password and keep it with you at all times until you've got it memorized. Then, destroy the piece of paper.
If you don't have dice, pick a password which is at least twelve characters long, and includes at least one lower case and upper case letter and at least one number or punctuation symbol. Don't forget your password, or all of 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 "Key Generation Completed" 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). This step is essential for your email self-defense, as you'll learn more about in Section 5.

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Advanced

Strong Passphrases with Diceware: Human-made passwords tend to either be very easy to guess, or difficult to memorise and easy to forget. Fortunately, if your privacy is more important to you than an extra 10 to 15 minutes of your time, you can use dice to come up with a password which is both strong and memorable using the 'diceware' method.; To use the diceware method, you will need dice (preferably 5, but 1 will do) and this list of words. Do not substitute computer dice for physical dice. Notice that each word on the word list corresponds to a unique five-digit number. Role one dice five times, or five dice once to select the first word. Don't rearrange or discard words, because doing so makes the process much less secure. Repeat this process until you have at least six words, and there's your password.
Command line key generation: If you prefer using the command line for a higher degree of control, you can follow the documentation from the GnuPG Mini Howto or The GNU Privacy Handbook. Make sure you stick with "RSA and RSA" (the default), because it's newer and more secure than algorithms recommended in the old previously mentioned documentation.; If you prefer using the command line for a higher degree of control, you can follow the documentation from The GNU Privacy Handbook. Make sure you stick with "RSA and RSA" (the default), because it's newer and more secure than the algorithms the documentation recommendeds. Also make sure your key is at least 2048 bits, or 4096 if you really want to be secure.
Advanced key pairs: When GnuPG creates a new keypair, it compartmentalizes the encryption function from the signing function through subkeys. If you use subkeys carefully, you can keep your GnuPG identity much more secure and recover from a compromised key much more quickly. Alex Cabal and the Debian wiki provide good guides for setting up a secure subkey configuration.

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Step 3.b Send a test encrypted email

Write a new email in your email program, addressed to edward-en@fsf.org. Make the subject "Encryption test" or something similar and write something in the body.

The key in the bottom right of the window should be yellow, meaning encryption is on. This will be your default from now on.

Next to the key, you'll notice an icon of a pencil. Clicking this tells Enigmail to add a special, unique 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.

Next to the key, you'll notice an icon of a pencil. We'll get to this in a moment.

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

To encrypt an email to Edward, you need his public key, 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 C), 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. Check the box in front of Edward's key and click Send.

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

Since you encrypted this email with Edward's public key, Edward's private key is required to decrypt it. Edward is the only one with his private key, so no one except him can decrypt it. Even you can't decrypt it, but your email program will automatically save a copy encrypted with your public key instead of Edwards, which you'll be able to view from the Sent folder like a normal email.

Troubleshooting

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Advanced

Encrypt messages from the command line: You can also encrypt and decrypt messages and files form the command line, if that's your preference.; You can also encrypt and decrypt messages and files form the command line, if that's your preference. The option --armor makes the encrypted output appear in the regular character set.

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Important: Security tips

Even if you encrypt 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 a surveillance system can still figure out who you're communicating with. Also, surveillance agents will know that you're using GnuPG, even if they can't figure out what you're saying. When you send attachments, Enigmail will give you an option of whether you want to encrypt them.

Encryption only works when you use it, so it's a good habit to double-check that email encryption is turned on before you hit send.

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Step 3.d Send a test signed email to a friend

GnuPG includes a way for you to sign messages and files, verifying that they came from you and that they weren't tampered with along the way. These signatures are stronger than their pen-and-paper cousins -- they're impossible to forge, because they're impossible to create without your private key (another reason to keep your private key safe).

You can sign messages to anyone (including people who haven't created their own keypair!) so it's a great way to promote GnuPG. To sign an email to a friend, click the pencil icon next to the lock icon so that it turns gold.If you sign a message, Enigmail will ask you for your password before it sends the message off. I will do this every time it needs to use your private key.

You can sign messages to anyone (including people who haven't created their own keypair!) so it's a great way to promote GnuPG. To sign an email to a friend, click the pencil icon next to the lock icon so that it turns gold. If you sign a message, Enigmail will ask you for your password before it sends the message off. It will do this every time it needs to use your private key.

When the pencil is gold but the lock is grey, the email will be signed but not encrypted. When the pencil is grey and the lock is gold, the email will be encrypted but not signed. When they're both gold, the email will be signed and encrypted.

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#4 Learn the Web of Trust

Email encryption is a powerful technology, but it has a weakness; it requires a way to verify that a person's public key is actually theirs. Otherwise, there would be no way to stop an attacker from making an email address with your friend's name, creating keys to go with it and impersonating your friend. That's why the free software programmers that developed email encryption created keysigning and the Web of Trust.

When you sign someone's key, you are publicly saying that you trust that it belongs to them and not an impostor. Signing keys and messages is the same type mathematical operation, but they carry very different implications. It's a good practice to generally sign your email, but if you casually sign people's keys, you may accidently end up vouching for the identity of an imposter. People who use your public key can see who has signed it. Once you've used GnuPG for a long time, you may have hundreds of signatures. The Web of Trust is the constellation of all GnuPG users, connected to each other by chains of trust expressed through signatures, forming a giant network. The more signatures of people you trust a key has, the more trustworthy that key is.

When you sign someone's key, you are publicly saying that you've verified that it belongs to them and not an impostor. Signing keys and messages is the same type mathematical operation, but they carry very different implications. It's a good practice to generally sign your email, but if you casually sign people's keys, you may accidently end up vouching for the identity of an imposter!

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People who use your public key can see who has signed it. Once you've used GnuPG for a long time, you may have hundreds of signatures. The Web of Trust is a constellation of GnuPG users, connected to each other by chains of trust expressed through signatures. The more signatures of people you trust a key has, the more trustworthy that key is.

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Important: check people's identification before signing their keys

Identifying keys: Fingerprints and IDs

People's public keys are usually identified by their key fingerprint, which is a string of digits like F357AA1A5B1FA42CFD9FE52A9FF2194CC09A61E8 (for Edward's key). You can see the fingerprint for your public key, and other public keys saved on your computer, by going to Enigmail → Key Management in your email program's menu, then right clicking on the key and choosing Key Properties. It's good practice to share your fingerprint wherever you share your email address, so that people can double-check that they have the correct public key when they download yours from a keyserver.

You may also see public keys referred to by their key ID, which is simply the last 8 digits of the fingerprint, like C09A61E8 for Edward. The key ID is visible directly from the Key Management window. This key ID is like a person's first name (it is a useful shorthand but may not be unique to a given key), whereas the fingerprint actually identifies the key uniquely without the possibility of confusion. If you only have the key ID, you can still look up the key (as well as its fingerprint), like you did in Step 3, but if multiple options appear, you'll need the fingerprint of the person to whom you are trying to communicate to verify which one to use.

You may also see public keys referred to by their key ID, which is simply the last eight digits of the fingerprint, like C09A61E8 for Edward. The key ID is visible directly from the Key Management window. This key ID is like a person's first name (it is a useful shorthand but may not be unique to a given key), whereas the fingerprint actually identifies the key uniquely without the possibility of confusion. If you only have the key ID, you can still look up the key (as well as its fingerprint), like you did in Step 3, but if multiple options appear, you'll need the fingerprint of the person to whom you are trying to communicate to verify which one to use.

Important: check people's identification before signing their keys

Before signing a real person's key, always make sure it actually belongs to them, and that they are who they say they are. Ask them to show you their ID (unless you trust them very highly) and their public key fingerprint -- not just the shorter public key ID, which could refer to another key as well. In Enigmail, answer honestly in the window that pops up and asks "How carefully have you verified that the key you are about to sign actually belongs to the person(s) named above?".

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Advanced

Master the Web of Trust: Unfortunately, trust does not spread between users the way many people think. One of best ways to strengthen the GnuPG community is to properly understand the web of trust and to carefully sign as many people's keys as circumstances permit.

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Important: act swiftly if someone gets your private key

If you lose your private key or someone else gets ahold of it (say, by stealing or cracking your computer), it's important to revoke it immediately before someone else uses it to read your encrypted email. This guide doesn't cover how to revoke a key, but you can follow the instructions on the GnuPG site. After you're done revoking, send an email to everyone with whom you usually use your key to make sure they know.

If you lose your private key or someone else gets ahold of it (say, by stealing or cracking your computer), it's important to revoke it immediately before someone else uses it to read your encrypted email or forge your signature. This guide doesn't cover how to revoke a key, but you can follow the instructions on the GnuPG site. After you're done revoking, send an email to everyone with whom you usually use your key to make sure they know.

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Webmail and GnuPG

When you use a web browser to access your email, you're using webmail, an email program stored on a distant website. Unlike webmail, your desktop email program runs on your own computer. Although webmail can't decrypt encrypted email, it will still display it in its encrypted form. If you primarily use webmail, you'll know to open your email client when you receive a scrambled email.