What I’m Using for Privacy: Email

in privacy, Tools
December 18th, 2016

This post is part of a series on technologies that I’m currently using for privacy, and my reasons for them. You can see the entire list in the first post

Email privacy is a tough nut to crack. To start, the protocol that’s used to move email around the internet, SMTP, is extremely simple and text-based. Email messages themselves are typically moved and stored as plain text. You know those fancy T0: and From: and Subject: fields that you see on every email message? They are just text…the email client you are using formats them based on the name. It’s trivial to forge emails to look like they are coming from someone else. Here’s an Instructable on how to do it.

Note that there are parts of the email transaction that are more difficult to forge, but if the target is an average user, it probably isn’t necessary to worry about those bits.

To provide some modicum of privacy for emails, many of us bolt on PGP encryption, which encrypts the email, or digitally signs it, or both. Note that the encryption covers just the body of the email message…the subject, to, from, and other headers are not encrypted, which means that a fair amount of metadata is being sent in the clear.

PGP is a strong solution for personal encryption. Unfortunately it is exceptionally difficult for the average user to set up and maintain. Even geeks have trouble with it. I’ve discussed my changing attitude toward PGP here in the blog, and many technologists who I respect highly are starting to turn away from it in favor of simpler, transactional, message-based systems like Signal.

The tldr; of my own post is that I will continue to use PGP to digitally sign my outgoing email (as I have been doing for many years) but will move to Signal for secure conversations. The PGP signature provides nonrepudiation to me, which is to say that I can prove whether or not a message was sent by me and whether is was altered once it left my hands.

So, I’m sticking with PGP and email.

But here’s the rub. I’m a Mac user, and MacOS Mail doesn’t support PGP. Worse, there’s no Apple supported API for Mail. There’s a project maintained by the folks at GPGTools that provides a plugin for Mail, however the method they use is to reverse-engineer each release of Mail to try to wedge their code in. This worked for a while, but the Sierra release of MacOS completely broke the plugin, and it’s not clear if it will ever work again.

Since I still want to use PGP to digitally sign my email, I’ve transitioned to Mozilla’s Thunderbird client. It is slightly less friendly than Apple Mail, but it does fully support plugins that provide PGP tools for both encryption and signing. I’m actually finding it to be a little more flexible than Apple Mail with filters and rules. Enigmail is the plugin that I’m using and it seems pretty straightforward.

If you are Windows user and have found a good solution, please send me a note and I’ll update this post for our Windows readers.

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