Implement Token Authenticated Registration flow (m.login.registration_token) in Element

[anoadragon453]

Description

This issue requests the implementation of Token Authenticated Registration (TAR) in Element Web, such that a token can be provided to the homeserver as part of the sign up flow.

What is Token Authenticated Registration?

As detailed in MSC3231, TAR allows homeserver admins to generate "registration tokens" to distribute to trusted friends and family in order to allow them to register an account.

A new User-Interactive Authentication stage, m.login.registration_token, allows clients to present a token to the homeserver in order to successfully complete registration.

An existing implementation of this feature exists in the nheko Matrix client: mtxclient library PR, nheko UI PR.

Equivalent PRs for Element Web would need to be made in matrix-js-sdk at the base layer, whereas the UI bits would live in the matrix-react-sdk and possibly element-web codebases.

Note that with all feature changes, you should expect to converse and receive sign-off from Element Web's UI/UX designers on this task for the user-interface portion of the feature.

[anoadragon453]

Note that this feature can be particularly useful for homeservers that want to enable semi-public registration, without having to be given a temporary password, or requiring the homeserver operator to set up potentially complex Single Sign-On infrastructure.

[fd1f]

this would be very useful to have included, and speed up registrations in situations like anoa describes! i hope the triage changes.

[ShadowJonathan]

I concur, @anoadragon453 this is likely to change to maybe O-Intermediate once conduit and synapse both implement this, conduit is already widely used for single or small-scope servers, so there'd definitely be demand from there.

Synapse 1.42.0 is the first synapse to include this, and conduit also wants to implement this (though that issue was made before the MSC was there)

[turt2live]

The triage is just for scoping, not for importance of an issue.

[GregSutcliffe]

For what it's worth, the Ansible community would find this very helpful as part of our Matrix rollout, and would be happy to take part in any appropriate discussions or trials.

[MacLemon]

We're fairydust.space and would love to see Token-Registration Support in Element as well. Since having open registration binds a lot of time for being ready to close again once the automated bot-registrations inevitably return. This time could be spent much better by having token support in Element!

[MexHigh]

Maybe a relevant update: As MSC3231 made it into to v1.2 matrix spec, synapse released a release candidate that already uses the stable endpoints (https://github.com/matrix-org/synapse/releases/tag/v1.53.0rc1).

[govynnus]

Yep, I've made a PR for matrix-js-sdk (matrix-org/matrix-js-sdk#2181) and am in the process of updating matrix-org/matrix-react-sdk#7275

[Half-Shot]

This is now in the spec, so we can probably drop the MSC name from the issue.