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Using Delta Chat with Chatmail servers for decentralized, open, secure, private messaging

On By In Tech

I’ve been using Delta Chat for a while, and I even made my own server for it (see: How to make your own Delta Chat Email Server and compete with WhatsApp/Signal/Telegram), but after I did that, other members of the Delta Chat developer community made new server software called “Chatmail” which is even better for use with Delta Chat. The Chatmail server software is still open-source of course (you can download it here:  GitHub – deltachat/chatmail: chatmail service deployment scripts and docs), and it uses popular open-source email programs; Dovecot and Postfix. So it’s still basically email, but there are some extra configurations and customizations.  

 

Firstly, Chatmail has an interface for automatically creating a new random email account and password. This makes onboarding from Delta Chat ridiculously easy. It amounts to: 

  1. Press the “Create New Profile” button
  2. Type in a name
  3. Press the “Agree & Create Profile” button

That’s right, no email address, no password, no phone number, no text message authorization code. It doesn’t ask for credit card information or your mailing address like Apple requires when you get an iPhone.  We’re talking seriously private and even anonymous. 

Next, the Chatmail servers will only send to people who you’ve got encryption keys exchanged with such that basically full encryption is the only way to communicate. It’s not like regular email servers where you can send unencrypted content just so it will work. Incidentally, most email servers these days have transport encryption via TLS, but the message body may not be encrypted while it’s sitting on your server.  It’s encrypted in transit between servers and devices, but maybe not while it’s on the device.  Delta Chat’s implementation of the open Autocrypt protocol mitigates that.  Other email programs are also implementing this full and easy encryption method so those should be compatible with Delta Chat’s implementation.

Thirdly, the Chatmail servers are usually configured to auto-delete old messages after 7 days and old accounts after 90 days of not being used. You can also set the Delta Chat app to delete messages after they’ve been received thus improving the privacy and security further. 

Fourth, the Chatmail servers have also implemented a connection to the Apple Push Notification Service. The good thing about that is with that Apple iPhone & iPad users will get push notifications when messages arrive. Basically, using Apple’s APN servers are the only way you can get instant push notifications on Apple iOS devices, so that was important. The problem with that is if you use an iOS device, you’ve got reduced privacy because Apple can see every notification you get that triggers the Delta Chat app to download new messages.  The Android, Windows, Linux, and MacOS Delta Chat client programs don’t have that problem because they are free to use the open standard IMAP IDLE push delivery protocol. 

Using Delta Chat

Now it’s important to remember that when using Delta Chat with Chatmail, the messages need to be encrypted, so setting up a secure encryption key exchange is the best way to do that.  Delta Chat can send public keys through the regular SMTP server method using the Autocrypt protocol, but a much better way to do it is using an in-person QR Code scan (CounterMITM) that exchanges keys through the camera. This is very easy to do if you’re standing right next to the person and both people have Delta Chat installed.  Simply:

  1. Tap the “+” button to start a new chat
  2. Tap the “New Contact” button at the top with a QR symbol icon next to it
  3. Tap the “QR Invite Code” button while the other person taps the “Scan QR Code” button
  4. Have the other person scan the code on your screen

That method of key exchange ensures that only the other person you just added will be able to read the messages you send them. It’s important to note that server operators will still be able to see metadata associated with the messages, such as date/time sent, user profile address, and subject field, but in the case of Delta Chat the subject field is always a useless “…” ellipses which doesn’t tell you anything, and the profile address created with Chatmail servers is an equally useless random set of letters and numbers. 

After you make secure contact connections, Delta Chat works like most other modern chat apps. It’s got the attachments, voice notes, read receipt indicators, location sharing, reaction emoji, etc. It also has video conferencing capabilities if you add a Jitsi Meet server URL to the settings. That’s another open-source server software that you can build a server for yourself or use one of the existing free ones. It would have been cool if the Chatmail server could also have a Jitsi Meet server built in and auto-configured, but maybe that can be a future enhancement.

Further Reading

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