Invisible Crypto: can Matrix be both secure and easy to use? (matrix-conf-2025)

The Invisible Crypto initiative intends to make Matrix easier to use by ensuring that encrypted messaging is secure by default, and the user is not bothered by irrelevant information. In this talk we will give a status update, hopefully explaining why crypto needed to become slightly more visible on the journey towards making it disappear. We'll go into some detail about what we've done (and why some of it makes things a little more noisy) and what we plan to do to really get there. We've been working on the Invisible Crypto initiative for over a year, and arguably things have got worse rather than better: some parts of Matrix crypto are more visible than they were before. We will go into some detail about what we've done so far and why those things temporarily make more noise, but will eventually lead to a peaceful, hassle-free experience of encrypted messaging. Most of the coding has been done in matrix-rust-sdk and the Element clients, but the intention is for these efforts to serve as examples for other implementations. Key goals of the initiative are to ignore "insecure" devices, and treat user identities as trust-on-first-use by default. To make these possible, we have worked on a lot of things that actually make crypto more visible: - Shields for messages from insecure devices - Encouraging device verification - Building a shared language to talk about crypto - Noticing and warning about devices with incomplete crypto information - Warnings about messages whose sender identity is unsure - Letting the user know when an identity changes and we plan to continue with things that mostly make crypto less visible, while also becoming more secure: - Excluding insecure devices - Authenticated backup - Sharing identity updates between devices - Fixing bugs that allow a device's crypto information to be incomplete - Showing identity changes in timelines instead of pop-ups - "Dehydrated" devices so messages received while logged out can be decrypted - Recovery key management Improving crypto-related code is always painstaking, but we hope to convince you that we are making steady progress, and demonstrate how you can help! Licensed to the public under https://creativecommons.org/licenses/by-sa/4.0/ about this event: https://cfp.2025.matrix.org/matrix-conf-2025/talk/BT8WR9/