How do you safely communicate over email?


Communicating safely over email is actually pretty complicated. I wanted to walk through the steps necessary in order to create a complete email identity online that should be reasonably safe against interception, network analysis and impersonation.

Before we begin, you need to have the Tor Browser Bundle installed. You also need to make sure that you never do anything related to your email account without having the connection going over Tor.

One important aspect of is the ability to find a good email provider where you don’t have to supply real personal information. If you ever have to supply your real information you will also always have to trust that the email provider does the right thing. The one thing you can never get away from is that network analysis can happen on your email if the provider can’t be trusted. If this happens, your only recourse is to be sure that the people you are talking to are using the same techniques, and that you are using several of these accounts for various activities.

The first step is to find a provider that matches your needs. For this I’m going to use RiseUp.net. I could also use hushmail or other services, although none of these are completely safe. I will first generate the email address/username I want. In order to do this, you need a mechanism of generating randomness. I will use 1Password for this, and generate a completely random string. However, an alternative you can use is to go to one of the random name generators available online (go there using Tor), and then generate a random name there. Once you have a random name and a long, really random password, you can go ahead and start registering for an account.

When signing up, use Tor for all the connections and make sure to not give any extra information asked for (such as time zone or country, for example). Once you have been completely signed up, use Tor again and sign in to the web client to make sure everything works as it should.

The next step is to create a private key specifically for this email account. I will use the command line to do this, using gpg. Before you create this key, you should also create a new pass phrase for yourself. Use the XKCD Battery Staple method, with about 5-6 words. However, be very careful to choose these words randomly. If you don’t use a random (really random) process, you lose all the benefits of having a pass phrase and it becomes a very weak password. So, once you have the pass phrase, you can use it to create a new private key:

gpg –gen-key

The choices I will make are these: RSA and RSA for the kind of key. A keysize of 4096, and a validity of 2 years. I will specify the username for the email address as the name for the key. Finally you will be asked for the pass phrase, so enter it now. Make sure to never push this key to a keyserver using the gpg program.

Once you have created the key, you should use the Tor browser to add it to the keyservers. First export the public key into a file. Make sure to not export the private part of the key. Once you have Tor up and running you can go to http://sks-keyservers.net/i and submit it there.

In order to use this account you should probably use Thunderbird and TorBirdy. If you have non-anonymous accounts you need to figure out how to run multiple Thunderbird instances, since TorBirdy takes over the full installation. You need a new profile and should install Enigmail and TorBirdy once you have the Thunderbird installed. Then you can go ahead and configure the mail account. It is important to install TorBirdy before you configure the mail account. Once you’ve configured the mail account, it’s a good idea to make sure Enigmail will encrypt and sign emails by default.

You are now ready to send safe and anonymous email. There are a few different things to keep in mind for this. First, make sure to never access this account over a regular connection. Second, never download keys automatically from the keyserver, instead always manually download and import it. Finally, never send an email in the clear. Always encrypt it using the right key. If you ever send an email like this in clear text over the same connection, you have lost most of the potential security of the account.

In order for this to work you should give your account information and fingerprint of the public key in person to the people who should have it.

Finally, all these things can not guarantee safety.

Comments and corrections to this writeup are very welcome.


2 Comments, Comment or Ping

  1. Jack Singleton

    I’d just add that if you do this much you probably also want to use a live linux distro from a thumb drive, and connect from public wifi.

    People reading should remember that low tech vulnerabilities are exploited just as much if not more than the software exploits most people think of as “hacking”. It’s not hard for someone to break into your house and walk away with your laptop.

    Liberte linux is a good distro to run while doing anything sensitive: /projects/liberte/

    It will automatically randomize your wifi mac address, comes preconfigured with tor, and saves your data back to the flash drive in an encrypted luks volume

    June 11th, 2013

  2. gamont

    What you think about these solutions ?
    /2013/09/15/dear-usa-my-data-has-left-your-building/

    September 28th, 2014

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