The Fediverse of Things


Binary code displayed on a screen.

One of the most frustrating things in modern technology is the effort spent trying to artificially restrict abundance. Take, for example, this tale from museum-worker Aaron Cope: I was out with a friend who worked for Twitter and I asked them whether it would be possible for the museum to “create 200,000 Twitter accounts, one […]

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How updates work in ActivityPub / Mastodon


Logo for ActivityPub.

I didn't realise this, so I'm documenting it to stop other people making the same silly mistake that I did. Messages in ActivityPub have two distinct ID strings. Here's a (truncated) view of what happens when I send a new message on Mastodon:   "id": "https://mastodon.social/users/Edent/statuses/1234567890/activity",   "type": "Create",   "actor": "https://mastodon.social/users/Edent",   "published": "2024-03-10T16:13:49Z", […]

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I made a mistake in verifying HTTP Message Signatures


A pet cat typing on a computer keyboard.

It's never great to find out you're wrong, but that's how learning and personal growth happens. HTTP Message Signatures are hard1. There are lots of complex parts and getting any aspect wrong means certain death2. In a previous post, I wrote A simple(ish) guide to verifying HTTP Message Signatures in PHP. It turns out that […]

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Updates to ActivityPub in a single PHP file


Logo for ActivityPub.

A few weeks ago, I built an ActivityPub Server in a Single PHP File. It's a proof of concept showing how easy it is to turn a website into a full-featured Fediverse participant. After a bunch of feedback and testing, I've added a some features to make it slightly more useful. A single PHP file […]

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A simple(ish) guide to verifying HTTP Message Signatures in PHP


Screenshot of JSON. As described in text.

Mastodon makes heavy use of HTTP Message Signatures. They're a newish almost-standard which allows a server to verify that a request made to it came from the person who sent it. This is a quick example to show how to verify these signatures using PHP. I don't claim that it covers every use-case, and it […]

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HTTP Signature Infinite Loop?


A padlock engraved into a circuit board.

I'm trying to get my head round HTTP Signatures as they're used extensively in the Fediverse. Conceptually, they're relatively straightforward. You send me a normal HTTP request. For example, you want to POST something to https://example.com/data You send me these headers: POST /data Host: example.com Date: Sat, 24 Feb 2024 14:43:48 GMT Accept-Encoding: gzip Digest: […]

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ActivityPub Server in a Single PHP File


Logo for ActivityPub.

Any computer program can be designed to run from a single file if you architect it wrong enough! I wanted to create the simplest possible Fediverse server which can be used as an educational tool to show how ActivityPub / Mastodon works. The design goals were: Upload a single PHP file to the server. No […]

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Internationalise The Fediverse


Translation icon. By Linh Nguyen.

We live in the future now. It is OK to use Unicode everywhere. It seems bizarre to me that modern Internet services sometimes "forget" that there's a world outside the Anglosphere. Some people have the temerity to speak foreign languages! And some of those languages have accents on their letters!! Even worse, some don't use […]

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A (tiny, incomplete, single user, write-only) ActivityPub server in PHP


Screenshot of a map. There is a pop-up containing an image of me drinking a pint.

I've written an ActivityPub server which only allows you to post messages to your followers. That's all it does. It won't record favourites or reposts. There's no support for following other accounts or receiving replies. It cannot delete or update posts nor can it verify signatures. It doesn't have a database or any storage beyond […]

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Rebuilding FourSquare for ActivityPub using OpenStreetMap


Map of London with several bits highlighted.

I used to like the original FourSquare. The "mayor" stuff was a bit silly, and my friends never left that many reviews, but I loved being able to signal to my friends "I am at this cool museum" or "We're at this pub if you want to meet" or "Spending the day at the park". […]

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