I installed delta.chat on my phone, to play with, nudged by Frank’s posting. It’s a E2E encrypted chat application with a twist: it uses e-mail as infrastructure. You set it up like an e-mail client, giving it access to one of your e-mail accounts. It will then use your e-mail account to send PGP encrypted messages.

So it’s actually a tool that brings you encrypted mail without the usual hassle of PGP set-up. Because it uses mail, you can find your messages in your regular mail archive (but encrypted), and you can contact anyone from the app if you have an e-mail address. The first message you send will be unencrypted (because you nor the app knows if the receiver has delta.chat installed), afterwards it will be encrypted as the app will have exchanged public encryption keys. Using e-mail means it’s robust, it doesn’t suffer from ‘there’s noone on here’ and there’s no silo lock-in. It also doesn’t need your phone number. It does ask for access to your contacts, which I denied as it is not at all a given that people will run delta.chat with the e-mail addresses they normally use.

I’ve tied it to my gmail address for now (ton dot zijlstra at gmail, ping me on delta.chat if you use it), because I wanted to have an easy interface to check what is going on in my inbox, and I have gmail on my phone anyway (even if I don’t use it for anything). I may switch over to a dedicated e-mail address later.

Some screenshots to illustrate:

How my initial exchange with Frank looked in Delta.chat

How my message to Frank looked in my mail. As it’s the first message it was unencrypted.

How I received Frank’s reply, which has an encrypted attachment.

The encrypted attachment when opened in a text editor shows it’s PGP.

I haven’t explored whether I can export my keys from Delta.chat. If you can’t, without Delta.chat I have no way of opening them. It’s a local tool only, so I suspect I might be able to get access to the keys outside of the app.