LibreFed

Highly experimental federation protocol using identity-based cryptography

Motivations

Existing federation protocols like ActivityPub have a number of problems, including nomadic identity (being able to freely move your account around instances) and having multiple AP accounts for Mastodon, PeerTube, WriteFreely, Gitea, etc.

Public-key identity

We can solve many of these problems by rethinking how our protocol handles federated identity. Instead of using the instance URL as part of the full username, we use the public-key to form the full username. For instance, your username might look like billiam@d981a0c873 instead of billiam@example.com, where that hex string is your public key. Your account can be associated with any number of instances, including instances of different software, and your data is incrementally replicated across all instances. If someone wants to message you, their instance either has the URLs of your data instances cached or you have to manually give them the URL of one of the instances (like in a traditional federation protocol).

Instances will store users' public keys encrypted, so only users will be able to sign messages, proving that they haven't been tampered with by any of the instances. This scheme is potentially vulnerable to MITM attacks, so this will have to be investigated in more depth later.

Replication

As mentioned earlier, user data is replicated across multiple instances. To maintain consistency, a CRDT can be used.