Good news in privacy for ActivityPub. The first early draft of the MLS over ActivityPub specification went out this week. It’s been part of my work on our E2EE for ActivityPub project at the Social Web Foundation.

Messaging Layer Security (MLS) is an IETF standard for end-to-end encrypted (E2EE) messaging. It lets people on laptops and phones communicate with each other in a secure way that no one in between can see.

MLS is designed to use pluggable lower-level protocols. This specification defines an envelope format for distributing MLS messages through the network, and an Activity Streams 2.0 profile for the packets of application data stored inside the messages.

This specification is ready for review from both ActivityPub developers and security analysts. It’s time to start making proof-of-concept implementations and testing interoperability.

The best place to make comments or report problems is on the ActivityPub E2EE GitHub repo issues list. I’m looking forward to these next steps!