Spec

Hey all,

Welcome to the second installment of our quarterly spec releases. If it feels like it hasn’t been long since our last release, you’re not alone! Our last release was just 3 months ago, introducing the new platform and world we build within.

This improvement in speed might seem too fast, but fret not: implementations are not expected to update as soon as the new spec is published. Rather, it is more realistic to expect that the ecosystem gradually update over the course of the following few months/year. Particularly after the massive release that was v1.1.

So, what’s new in v1.2? With 18 MSCs merged there’s a lot to cover - we’ve picked some notable highlights and recommend the full changelog at the bottom for a complete idea of what’s been going on.

Rearchitecting with Spaces

Spaces launched into beta last May, redefining how we can use rooms on Matrix to represent different data structures. Described mostly as MSC1772, Spaces are simply rooms with a specific type in their m.room.create event. With state events being used to define which other rooms (meaning Spaces too) are part of that Space, the possibilities for tree-like structured data become endless.

There’s still quite a lot of work to do in the Spaces space (hah), though we’re excited to see it all land. For instance, MSC3216 and MSC2962 target power level syncing, MSC3219 aims for flair, and MSC3089 looks at file structures using Spaces. We might even be able to replace the public room directory with a server-wide space, making writing clients a little bit easier.

Public, but not too public, join rules

Restricted rooms are new in this release from MSC3083. In these rooms (and therefore Spaces too!), the join rules can be configured such that a member of another room can join without needing an invite. In a typical setup, this means that a Space could be set as invite-only, but all the rooms and Spaces underneath that Space could allow joins for members of the parent Space. When someone wishes to explore the universe you’ve laid out in your Space they can simply join the interesting rooms without having to ask for invites constantly.

This feature changes how membership events are authorized, so is only available in room versions 8 and 9 (both introduced in this release). Room version 9 fixes a relatively rare bug from version 8, so we’d recommend using v9 if you’re planning an upgrade for this functionality.

Further work in this area involves figuring out how to keep membership lists perfectly in sync between the rooms, which is currently done by external tooling. For example, evicting someone from the parent Space could (optionally) evict the user from all the subsequent rooms and Spaces too.

We also need to figure out how to support both knocking and restricted rooms at the same time (oops). MSC3613 and MSC3386 both tackle this problem in different ways and timescales.

Matrix: A URI

A massive shoutout goes to kitsune and the whole community for working on MSC2312, giving us a URI we can pass around outside of Matrix to bring us back in. The early work on this dates all the way back to 2014, the very beginning of Matrix’s development, and has since been marked Provisional by the IANA.

The full spec is available here - feel free to discuss it at matrix:r/matrix-spec:matrix.org ;)

The full changelog

MSCs are how the spec changes in the way it does - adding, fixing, and maintaining features for the whole ecosystem to use. The blog post can’t cover them all, but that doesn’t make them any less important! Check out the full changelog below, and the Spec Change Proposals page for more information on how these MSCs got merged (hint: they submitted a proposal, which anyone can do - take a look at the Matrix Live episode where Matthew covers the proposal process).

Client-Server API

Breaking Changes

• The prev_content field is now returned inside the unsigned property of events, rather than at the top level, as per MSC3442. (#3524)
• The aliases property from the chunks returned by /publicRooms, as per MSC2432. (#3624)

New Endpoints

• Add the Space Hierarchy API (GET /_matrix/client/v1/rooms/{roomId}/hierarchy) as per MSC2946. (#3610)
• Add /_matrix/client/v1/register/m.login.registration_token/validity as per MSC3231. (#3616)

Backwards Compatible Changes

• Extend /_matrix/client/r0/login to accept a m.login.appservice, as per MSC2778. (#3324)
• Add support for restricted rooms as per MSC3083, MSC3289, and MSC3375. (#3387)
• Add is_guest to /account/whoami as per MSC3069. (#3605)
• Expand guest access to sending any room event and state event as per MSC3419. (#3605)
• Add Spaces and room types as per MSC1772 and MSC2946. (#3610)
• Add new m.set_displayname, m.set_avatar_url, and m.3pid_changes capabilities as per MSC3283. (#3614)
• Add support for fallback keys (optional keys used once one-time keys run out), as per MSC2732. (#3615)
• Add token-authenticated registration support as per MSC3231. (#3616)

Spec Clarifications

• Make AesHmacSha2KeyDescription consistent with KeyDescription in marking name as optional. (#3481)
• Fix various typos throughout the specification. (#3482, #3495, #3509, #3535, #3591, #3601, #3611, #3671, #3680)
• Explicitly mention RFC5870 in the definition of m.location events (#3492)
• Add 403 M_FORBIDDEN error code to /profile/{userId} as per MSC3550. (#3530)
• Clarify the description of the /sync API, including a fix to an ASCII art diagram. (#3543)
• Clarify that base_url in client well_known may or may not include trailing slash. (#3562)
• Clarify which signature to check when decrypting m.olm.v1.curve25519-aes-sha2 messages. (#3573)
• Clarify what "Stripped State" is and what purpose it serves, as per MSC3173. (#3606)
• Clarify how to interpret missing one-time key counts. (#3636)
• Correct the schema for the responses for various API endpoints. (#3650)
• Clarify that group mentions are no longer in the specification. (#3652)
• Distinguish between "federation" event format as exchanged by the Federation API, and the "client" event formats as used in the client-server and AS APIs. (#3658)
• Fix the rendering of the responses for various API endpoints. (#3674)

Server-Server API

New Endpoints

• Add the Space Hierarchy API (GET /_matrix/federation/v1/hierarchy/{roomId}) as per MSC2946. (#3610, #3660)

Backwards Compatible Changes

• Add support for restricted rooms as per MSC3083, MSC3289, and MSC3375. (#3387)

Spec Clarifications

• Fix various typos throughout the specification. (#3527)
• Clarify that GET /_matrix/federation/v1/event_auth/{roomId}/{eventId} does not return the auth chain for the full state of the room. (#3583)
• Fix the rendering of the responses for various API endpoints. (#3674)

Application Service API

Spec Clarifications

• Distinguish between "federation" event format as exchanged by the Federation API, and the "client" event formats as used in the client-server and AS APIs. (#3658)
• Fix the rendering of the responses for various API endpoints. (#3674)
• Correct the documentation for the response value for GET /_matrix/app/v1/thirdparty/protocol/{protocol}. (#3675)

Identity Service API

Backwards Compatible Changes

• Add the room_type to stored invites as per MSC3288. (#3610)

Spec Clarifications

• Fix the rendering of the responses for various API endpoints. (#3674)

Push Gateway API

Spec Clarifications

• Fix the rendering of the responses for various API endpoints. (#3674)

Room Versions

Backwards Compatible Changes

• Add Room Version 8 as per MSC3289. (#3387)
• Add Room Version 9 as per MSC3375. (#3387)

Spec Clarifications

• Fully specify room versions to indicate what exactly is carried over from parent versions. (#3432, #3661)
• Clarifications to sections on event IDs and event formats. (#3501)
• Remove a number of fields which were incorrectly shown to form part of the unsigned data of a Federation PDU. (#3522)
• Fix heading order of room version specifications to be consistent. (#3683)
• Add missing "Signing key validity period" section to room version 6. (#3683)
• Fix auth rules to allow membership of knock -> leave in v7, v8, and v9. (#3694)

Appendices

Backwards Compatible Changes

• Describe "Common Namespaced Identifier Grammar" as per MSC2758. (#3171)
• Describe the matrix: URI scheme as per MSC2312. (#3608)

Hey all,

Once again it's been a little while since we've done a spec release (sorry; we're aiming for quarterly releases from here on out), but this time we have some pretty big news: we've got an all-new spec platform and a new versioning scheme. The new spec platform has been needed for a long time to make better sense of what Matrix is, and as part of getting that out the door we reduced the number of "Matrix versions" to just one.

Huge thanks to Will Bamberg for building it out for us, anoa for working out the deployment details, and everyone for testing it all. They talk at length about what this specification even is and about the platform itself on Matrix Live S6E19. It's the single greatest improvement to the spec we've seen to date.

The new versioning scheme presents the whole specification as a single document, making it easier to check compatibility between implementations and the spec itself. Previously, a grid would have to be drawn to show whether Server-Server r0.1.4 is compatible with Client-Server r0.6.1 - while obvious at release time, the historical context gets lost quite easily. Now, with a single version number, the entire specification is compatible across a single version number: servers implementing Matrix 1.1 will be compatible with clients implementing v1.1, and vice versa. For the specification itself, this means we no longer have to carefully point and update links between the APIs, as they'll instead be versioned together.

Changing the versioning of the specification does have an impact on the Client-Server API in particular, however. You may have noticed that Client-Server APIs are currently versioned at "r0". By removing rX.Y.Z versioning, all of the endpoints suddenly don't have a version to reference. All endpoints across the specification are now versioned individually to allow for breaking changes at the endpoint level. They no longer require the whole specification to be listed as a breaking change: a v1 endpoint can get additions/changes which are backwards compatible, but if we need to change format (for example) then it'll get bumped up to v2, leaving v1 in its last known state.

For the Client-Server API, a slight complication is that v1 and v2 (alpha) are already versions familiar to those that have been around for a while - to avoid confusing those people, existing Client-Server API endpoints will start at v3. New endpoints introduced after v1.1 will start at v1 instead.

It's been well over a year since the last release, which means there's a whole lot of features and changes to cover. Here we'll try to cover the things most clients/servers will have to worry about, but we do still recommend reading through the changelog included below. Overall, 28 MSCs have been merged through this release, but some have had to be excluded in the interest of getting the spec release out there. Many of them are expected to be in the next anticipated release (which should hopefully be next quarter).

Clients: There's a lot of stuff

In Matrix 1.1, client developers get all sorts of new features to play with. Clients which support end-to-end encryption should explore key backups, cross-signing, SSSS, and breaking changes to verification. Quite a lot of this stuff has existed for a while, but has made it into the specification formally now. As an added bonus, the emoji for SAS verification have been translated (contribute here).

Knocking has also landed in the spec (thanks Sorunome for leading the charge on this!), opening up the ability for rooms to optionally allow people to request invites to join. This can be helpful for semi-private rooms where it can be easier to approve/deny requests compared to finding someone's MXID and manually inviting them. This does require a v7 room to work, however.

Thanks again to Sorunome, Message Spoilers have been officially included in Matrix. People can now safely discuss the ending to the latest movie without being banned for spoilers. Though, as a new feature, there's a chance that the spoiler text still gets included in the message: clients should update as soon as possible to avoid their users accidentally getting banned for spoiling the conclusion to the Spaces saga ;)

There's a few other smaller improvements/additions, and of course the regular "various clarifications and bug fixes" to take a look at. For a sample checklist, check out element-web's issue on the subject.

Servers: Knock knock, it's a new room version

Room version 7 has landed, bringing forth the ability for users to knock on rooms (requesting an invite to join). The changes are largely scoped to using the reserved keywords for join rules and membership, and are described through the auth rules. Thankfully, the changes over v6 are minimally invasive so should be quick to implement.

Additionally, the cross-signing bits have been included in the API responses and EDU definitions. Matthew's blog post from last year (it really has been that long...) describes cross-signing and the history of its implementation.

As per usual, there's also various specification errors corrected to aid understanding. Synapse has an exhaustive issue to detail what servers might need to do.

PS: Room versions 8 and 9 are also out there, but will be included in a future spec release.

The full changelog

We haven't mentioned identity servers, bridges, etc in this post but they have changes too! Below is the whole changelog, the entire year and a bit of it. Thank you to everyone who has submitted MSCs, and congratulations on getting them released. If we forgot yours, please mention it in #matrix-spec:matrix.org so we can apologize and correct.

PS: The MSC process is how changes to Matrix are made, and you (yes, you) can propose those changes too. Check out the Matrix Live episode where Matthew talks about how this process works, and how we avoid blocking clients from implementing their proposals behind the relatively slow spec release cycles.

Client-Server API

Breaking Changes

• Document curve25519-hkdf-sha256 key agreement method for SAS verification, and deprecate old method as per MSC2630. (#2687)
• Add m.key.verification.ready and m.key.verification.done to key verification framework as per MSC2366. (#3139)

Deprecations

• Deprecate starting verifications that don't start with m.key.verification.request as per MSC3122. (#3199)

New Endpoints

• Add key backup (/room_keys/*) endpoints as per MSC1219. (#2387, #2639)
• Add POST /keys/device_signing/upload and POST /keys/signatures/upload as per MSC1756. (#2536)
• Add /knock endpoint as per MSC2403. (#3154)
• Add /login/sso/redirect/{idpId} as per MSC2858. (#3163)

Removed Endpoints

• Remove unimplemented m.login.oauth2 and m.login.token user-interactive authentication mechanisms as per MSC2610 and MSC2611. (#2609)

Backwards Compatible Changes

• Document how clients can advise recipients that it is withholding decryption keys as per MSC2399. (#2399)
• Add cross-signing properties to the response of POST /keys/query as per MSC1756. (#2536)
• Document Secure Secret Storage and Sharing as per MSC1946 and MSC2472. (#2597)
• Add a device_id parameter to login fallback as per MSC2604. (#2709)
• Added a common set of translations for SAS Emoji. (#2728)
• Added support for reason on all membership events and related endpoints as per MSC2367. (#2795)
• Add a 404 M_NOT_FOUND error to push rule endpoints as per MSC2663. (#2796)
• Make reason and score parameters optional in the content reporting API as per MSC2414. (#2807)
• Allow guests to get the list of members for a room as per MSC2689. (#2808)
• Add support for spoilers as per MSC2010 and MSC2557, and color attribute as per MSC2422. (#3098)
• Add <details> and <summary> to the suggested HTML subset as per MSC2184. (#3100)
• Add key verification using in-room messages as per MSC2241. (#3139, #3150)
• Add information about using SSSS for cross-signing and key backup. (#3147)
• Add key verification method using QR codes as per MSC1544. (#3149)
• Document how clients can simplify usage of Secure Secret Storage as per MSC2874. (#3151)
• Add support for knocking, as per MSC2403. (#3154, #3254)
• Multiple SSO providers are possible through m.login.sso as per MSC2858. (#3163)
• Add device_id to /account/whoami response as per MSC2033. (#3166)
• Downgrade identity server discovery failures to FAIL_PROMPT as per MSC2284. (#3169)
• Re-version all endpoints to be v3 as a starting point instead of r0 as per MSC2844. (#3421)

Spec Clarifications

• Fix issues with age and unsigned being shown in the wrong places. (#2591)
• Fix definitions for room version capabilities. (#2592)
• Fix various typos throughout the specification. (#2594, #2599, #2809, #2878, #2885, #2888, #3116, #3339)
• Clarify link to OpenID Connect specification. (#2605)
• Clarify the behaviour of SSO login and UI-Auth. (#2608)
• Remove spurious room_id from /sync examples. (#2629)
• Reorganize information in Push Notifications module for clarity. (#2634)
• Improve consistency and clarity of event schema titles. (#2647)
• Fix schema issues in m.key.verification.accept and secret storage. (#2653)
• Reword "UI Authorization" to "User-Interactive Authentication" to be more clear. (#2667)
• Fix schemas for push rule actions to represent their alternative object form. (#2669)
• Fix usage of highlight tweak for consistency. (#2670)
• Clarify the behaviour of state for /sync with lazy-loading. (#2754)
• Clarify description of m.room.redaction event. (#2814)
• Mark messages as a required JSON body field in PUT /_matrix/client/r0/sendToDevice/{eventType}/{txnId} calls. (#2928)
• Correct examples of client_secret request body parameters so that they do not include invalid characters. (#2985)
• Fix example MXC URI for m.presence. (#3091)
• Clarify that event bodies are untrusted, as per MSC2801. (#3099)
• Fix the maximum event size restriction (65535 bytes -> 65536). (#3127)
• Update Access-Control-Allow-Headers recommendation to fit CORS specification. (#3225)
• Explicitly state that replacement_room is a room ID in m.room.tombstone events. (#3233)
• Clarify that all request bodies are required. (#3238, #3332)
• Add missing titles to some scheams. (#3330)
• Add User-Interactive Authentication fields to cross-signing APIs as per MSC1756. (#3331)
• Mention that a canonical alias event should be added when a room is created with an alias. (#3337)
• Add an 'API conventions' section to the Appendices. (#3350)
• Clarify the documentation around the pagination tokens used by /sync, /rooms/{room_id}/messages, /initialSync, /rooms/{room_id}/initialSync, and /notifications. (#3353)
• Remove the inaccurate 'Pagination' section. (#3366)
• Clarify how redacted_because is meant to work. (#3411)
• Remove extraneous mimetype from EncryptedFile examples, as per MSC2582. (#3412)
• Describe how MSC2844 affects the /versions endpoint. (#3420)
• Fix documentation errors around threepid_creds. (#3471)

Server-Server API

New Endpoints

• Add /make_knock and /send_knock endpoints as per MSC2403. (#3154)

Backwards Compatible Changes

• Add cross-signing information to GET /user/keys and GET /user/devices/{userId}, m.device_list_update EDU, and a new m.signing_key_update EDU as per MSC1756. (#2536)
• Add support for knocking, as per MSC2403. (#3154)

Spec Clarifications

• Specify that GET /_matrix/federation/v1/make_join/{roomId}/{userId} can return a 404 if the room is unknown. (#2688)
• Fix various typos throughout the specification. (#2888, #3116, #3128, #3207)
• Correct the /_matrix/federation/v1/user/devices/{userId} response which actually returns "self_signing_key" instead of "self_signing_keys". (#3312)
• Explain the reasons why <hostname> TLS certificate is needed rather than <delegated_hostname> for SRV delegation. (#3322)
• Tweak the example PDU diagram to better demonstrate situations with multiple prev_events. (#3340)

Application Service API

Spec Clarifications

• Fix various typos throughout the specification. (#2888)

Identity Service API

New Endpoints

• Add GET /_matrix/identity/versions API as per MSC2320. (#3101)

Removed Endpoints

• The v1 identity service API has been removed in favour of the v2 API, as per MSC2713. (#3170)

Spec Clarifications

• Fix various typos throughout the specification. (#2888)
• Clarify that some identifiers must be case folded prior to processing, as per MSC2265. (#3167, #3176)
• Describe how MSC2844 affects the /versions endpoint. (#3459)

Push Gateway API

Spec Clarifications

• Clarify where to get information about the various parameter values for the notify endpoint. (#2763)

Room Version 6, Client-Server r0.6.1, and Federation r0.1.4 spec releases

Hey all,

It's been a little while since we've done a spec release, so here we are with Room Version 6, Client-Server r0.6.1, and Federation r0.1.4.

Room Version 6 (and the associated Federation r0.1.4 release) is largely something for implementations to worry about. It contains new event authorisation rules, changes to the redaction algorithm, and stricter compliance for JSON.

Client-Server r0.6.1 contains a number of clarifications as well as SSO support for authorisation, "soft logout" to avoid needlessly destroying e2e history, and new ways to publish aliases within rooms.

If you're wondering where all the E2E-by-default related MSCs are - we're doing final iterations based on the real-world feedback from the E2E-by-default launch a few weeks ago, and they are then expected to land in the upcoming Client-Server r0.7.

Here's all the MSCs that got merged since the last release:

• MSC2240: Room version 6
• MSC2457: Invalidating devices during password modification
• MSC2454: Support UI auth for SSO
• MSC2451: Remove query_auth federation endpoint
• MSC2432: Updated semantics for publishing room aliases
• MSC2324: Facilitating early releases of software dependent on spec
• MSC2313: Moderation policies as rooms
• MSC1466: Soft Logout
• MSC2540: Stricter event validation: JSON compliance
• MSC2209: Alter auth rules to check notifications in m.room.power_levels
• MSC1802: Remove the '200' value from some federation responses

Client-Server r0.6.1 changelog

New Endpoints

• Added /rooms/{roomId}/aliases for retrieving local aliases for a room. (#2562)

Backwards Compatible Changes

• Added data structures for defining moderation policies in rooms per MSC2313. (#2434)
• Optionally invalidate other access tokens during password modification per MSC2457. (#2523)
• Add User-Interactive Authentication for SSO-backed homeserver per MSC2454. (#2532)
• Add soft-logout support per MSC1466. (#2546)
• Replaced legacy room alias handling with a more sustainable solution per MSC2432. (#2562)

Spec Clarifications

• List available enum values for the room versions capability. (#2245)
• Fix various spelling errors throughout the specification. (#2351, #2415, #2453, #2524, #2553, #2569)
• Minor clarifications to token-based User-Interactive Authentication. (#2369)
• Minor clarification for what the user directory searches. (#2381)
• Fix key export format example to match the specification. (#2430)
• Clarify the IV data type for encrypted files. (#2492)
• Fix the .m.rule.contains_user_name default push rule to set the highlight tweak. (#2519)
• Clarify that an event_id is returned when sending events. (#2525)
• Fix some numbers in the specification to match their explanation text. (#2554)
• Move redaction algorithm into the room version specifications. (#2563)
• Clarify signature object structures for encryption. (#2566)
• Clarify which events are created as part of /createRoom. (#2571)
• Remove claims that the homeserver is exclusively responsible for profile information in membership events. (#2574)

Server-Server (Federation) r0.1.4 changelog

New Endpoints

• Add new POST /publicRooms endpoint for filtering the room directory. (#2305)
• Add new v2 /send_join and /send_leave endpoints per MSC1802. (#2547)

Removed Endpoints

• Remove the unused query_auth API per MSC2451. (#2470)

Spec Clarifications

• Move auth event selection to a more obvious location. (#2392)
• Fix typo in Request Authentication python example. (#2510)
• Clarify which fields are required on the key server endpoints. (#2527)
• Clarify the limits of prev_events and auth_events for PDUs. (#2538)
• Clarify which events are targeted by backfill. (#2559)
• Fix the response format of the /send endpoint. (#2560)
• Clarify signature object structures for encryption. (#2566)
• Clarify the server names to use when signing requests. (#2570)
• Clarify the state/auth chain requirements for /send_join. (#2575)
• Fix various spelling errors throughout the specification. (#2577)

Hey all,

For the last several months the team has been working on tightening up privacy in Matrix, and with the 1.4 release of Synapse and Riot quite a lot has been done in the area. One of the remaining pieces was to release all the specification changes to help other client/server implementations achieve the same goals, and now we've done that.

The Client-Server r0.6.0 and Identity Service r0.3.0 spec releases both cover the privacy improvements added through a number of MSCs in the last few months. Of particular note is that identity servers are now expected to support terms of service endpoints, which requires authentication that clients might need to worry about - check the spec changelogs for details.

The full changelog for the Client-Server r0.6.0 release is:

• Breaking Changes

  • Add id_access_token as a required request parameter to a few endpoints which require an id_server parameter as part of MSC2140. (#2255)

• New Endpoints

  • Add POST /account/3pid/unbind for removing a 3PID from an identity server. (#2282)

• Backwards Compatible Changes

  • Add M_USER_DEACTIVATED error code. (#2234)
  • Remove bind_msisdn and bind_email from /register now that the identity server's bind endpoint requires authentication. (#2279)
  • Add m.identity_server account data for tracking the user's preferred identity server. (#2281)
  • Deprecate id_server and make it optional in several places. (#2310)

• Spec Clarifications

  • Add missing format fields to m.room.message$m.notice schema. (#2125)
  • Remove "required" designation from the url field of certain m.room.message msgtypes. (#2129)
  • Fix various typos throughout the specification. (#2131, #2136, #2148, #2215)
  • Clarify the distinction between m.key.verification.start and its m.sas.v1 variant. (#2132)
  • Fix link to Olm signing specification. (#2133)
  • Clarify the conditions for the .m.rule.room_one_to_one push rule. (#2152)
  • Clarify the encryption algorithms supported by the device of the device keys example. (#2157)
  • Clarify that /rooms/:roomId/event/:eventId returns a Matrix error. (#2204)
  • Add a missing state_key check on .m.rule.tombstone. (#2223)
  • Fix the m.room_key_request action value, setting it from cancel_request to request_cancellation. (#2247)
  • Clarify that the submit_url field is without authentication. (#2341)
  • Clarify the expected phone number format. (#2342)
  • Clarify that clients should consider not requesting URL previews in encrypted rooms. (#2343)
  • Add missing information on how filters are meant to work with /context. (#2344)
  • Clarify what the keys are for rooms in /sync. (#2345)

The full changelog for the Identity Service r0.3.0 release is:

• New Endpoints

  • Add /account, /account/register, and /account/logout to authenticate with the identity server. (#2255)
  • Add endpoints for accepting and handling terms of service. (#2258)
  • Add /hash_details and a new /lookup endpoint for performing hashed association lookups. (#2287)

• Backwards Compatible Changes

  • Deprecate the v1 API in favour of an authenticated v2 API. (#2254)