I have some concerns about Matrix (the protocol, not the movie that came out recently, although I do have concerns about that as well). I've been watching the project for a long time, and it seems more a promising alternative to many protocols like IRC, XMPP, and Signal.

This review may sound a bit negative, because it focuses on those concerns. I am the operator of an IRC network and people keep asking me to bridge it with Matrix. I have myself considered just giving up on IRC and converting to Matrix. This space is a living document exploring my research of that problem space. The TL;DR: is that no, I'm not setting up a bridge just yet, and I'm still on IRC.

This article was written over the course of the last three months, but I have been watching the Matrix project for years (my logs seem to say 2016 at least). The article is rather long. It will likely take you half an hour to read, so copy this over to your ebook reader, your tablet, or dead trees, and lean back and relax as I show you around the Matrix. Or, alternatively, just jump to a section that interest you, most likely the conclusion.

  1. Introduction to Matrix
  2. Security and privacy
    1. Data retention defaults
    2. GDPR in the federation
    3. Matrix.org privacy policy
    4. Metadata handling
    5. Amplification attacks on URL previews
  3. Moderation
    1. The mjolnir bot
    2. The command-line tool
    3. Rate limiting
    4. Fundamental federation problems
    5. Room admins
  4. Availability
    1. How this works in IRC
    2. User identities
    3. Rooms
    4. Spaces
    5. Home servers
    6. Delegations
  5. Performance
    1. Horizontal scalability
    2. Other implementations
    3. Latency
    4. Transport
  6. Usability
    1. Onboarding and workflow
    2. 5 minute clients evaluation
    3. Bots
    4. Working on Matrix
  7. Conclusion
    1. Looking back at history
    2. Where the federated services are in history

Introduction to Matrix

Matrix is an "open standard for interoperable, decentralised, real-time communication over IP. It can be used to power Instant Messaging, VoIP/WebRTC signalling, Internet of Things communication - or anywhere you need a standard HTTP API for publishing and subscribing to data whilst tracking the conversation history".

It's also (when compared with XMPP) "an eventually consistent global JSON database with an HTTP API and pubsub semantics - whilst XMPP can be thought of as a message passing protocol."

According to their FAQ, the project started in 2014, has about 20,000 servers, and millions of users. Matrix works over HTTPS but over a special port: 8448.

Security and privacy

I have some concerns about the security promises of Matrix. It's advertised as a "secure" with "E2E [end-to-end] encryption", but how does it actually work?

Data retention defaults

One of my main concerns with Matrix is data retention, which is a key part of security in a threat model where (for example) an hostile state actor wants to surveil your communications and can seize your devices.

On IRC, servers don't actually keep messages all that long: they pass them along to other servers and clients as fast as they can, only keep them in memory, and move on to the next message. There are no concerns about data retention on messages (and their metadata) other than the network layer. (I'm ignoring the issues with user registration, which is a separate, if valid, concern.) Obviously, an hostile server could log everything passing through it, but IRC federations are normally tightly controlled. So, if you trust your IRC operators, you should be fairly safe. Obviously, clients can (and often do, even if OTR is configured!) log all messages, but this is generally not the default. Irssi, for example, does not log by default. IRC bouncers are more likely to log to disk, of course, to be able to do what they do.

Compare this to Matrix: when you send a message to a Matrix homeserver, that server first stores it in its internal SQL database. Then it will transmit that message to all clients connected to that server and room, and to all other servers that have clients connected to that room. Those remote servers, in turn, will keep a copy of that message and all its metadata in their own database, by default forever. On encrypted rooms those messages are encrypted, but not their metadata.

There is a mechanism to expire entries in Synapse, but it is not enabled by default. So one should generally assume that a message sent on Matrix is never expired.

GDPR in the federation

But even if that setting was enabled by default, how do you control it? This is a fundamental problem of the federation: if any user is allowed to join a room (which is the default), those user's servers will log all content and metadata from that room. That includes private, one-on-one conversations, since those are essentially rooms as well.

In the context of the GDPR, this is really tricky: who is the responsible party (known as the "data controller") here? It's basically any yahoo who fires up a home server and joins a room.

In a federated network, one has to wonder whether GDPR enforcement is even possible at all. But in Matrix in particular, if you want to enforce your right to be forgotten in a given room, you would have to:

  1. enumerate all the users that ever joined the room while you were there
  2. discover all their home servers
  3. start a GDPR procedure against all those servers

I recognize this is a hard problem to solve while still keeping an open ecosystem. But I believe that Matrix should have much stricter defaults towards data retention than right now. Message expiry should be enforced by default, for example. (Note that there are also redaction policies that could be used to implement part of the GDPR automatically, see the privacy policy discussion below on that.)

Also keep in mind that, in the brave new peer-to-peer world that Matrix is heading towards, the boundary between server and client is likely to be fuzzier, which would make applying the GDPR even more difficult.

Update: this comment links to this post (in german) which apparently studied the question and concluded that Matrix is not GDPR-compliant.

In fact, maybe Synapse should be designed so that there's no configurable flag to turn off data retention. A bit like how most system loggers in UNIX (e.g. syslog) come with a log retention system that typically rotate logs after a few weeks or month. Historically, this was designed to keep hard drives from filling up, but it also has the added benefit of limiting the amount of personal information kept on disk in this modern day. (Arguably, syslog doesn't rotate logs on its own, but, say, Debian GNU/Linux, as an installed system, does have log retention policies well defined for installed packages, and those can be discussed. And "no expiry" is definitely a bug.

Matrix.org privacy policy

When I first looked at Matrix, five years ago, Element.io was called Riot.im and had a rather dubious privacy policy:

We currently use cookies to support our use of Google Analytics on the Website and Service. Google Analytics collects information about how you use the Website and Service.

[...]

This helps us to provide you with a good experience when you browse our Website and use our Service and also allows us to improve our Website and our Service.

When I asked Matrix people about why they were using Google Analytics, they explained this was for development purposes and they were aiming for velocity at the time, not privacy (paraphrasing here).

They also included a "free to snitch" clause:

If we are or believe that we are under a duty to disclose or share your personal data, we will do so in order to comply with any legal obligation, the instructions or requests of a governmental authority or regulator, including those outside of the UK.

Those are really broad terms, above and beyond what is typically expected legally.

Like the current retention policies, such user tracking and ... "liberal" collaboration practices with the state set a bad precedent for other home servers.

Thankfully, since the above policy was published (2017), the GDPR was "implemented" (2018) and it seems like both the Element.io privacy policy and the Matrix.org privacy policy have been somewhat improved since.

Notable points of the new privacy policies:

I'm not super happy with all the trackers they have on the Element platform, but then again you don't have to use that service. Your favorite homeserver (assuming you are not on Matrix.org) probably has their own Element deployment, hopefully without all that garbage.

Overall, this is all a huge improvement over the previous privacy policy, so hats off to the Matrix people for figuring out a reasonable policy in such a tricky context. I particularly like this bit:

We will forget your copy of your data upon your request. We will also forward your request to be forgotten onto federated homeservers. However - these homeservers are outside our span of control, so we cannot guarantee they will forget your data.

It's great they implemented those mechanisms and, after all, if there's an hostile party in there, nothing can prevent them from using screenshots to just exfiltrate your data away from the client side anyways, even with services typically seen as more secure, like Signal.

As an aside, I also appreciate that Matrix.org has a fairly decent code of conduct, based on the TODO CoC which checks all the boxes in the geekfeminism wiki.

Metadata handling

Overall, privacy protections in Matrix mostly concern message contents, not metadata. In other words, who's talking with who, when and from where is not well protected. Compared to a tool like Signal, which goes through great lengths to anonymize that data with features like private contact discovery, disappearing messages, sealed senders, and private groups, Matrix is definitely behind. (Note: there is an issue open about message lifetimes in Element since 2020, but it's not at even at the MSC stage yet.)

This is a known issue (opened in 2019) in Synapse, but this is not just an implementation issue, it's a flaw in the protocol itself. Home servers keep join/leave of all rooms, which gives clear text information about who is talking to. Synapse logs may also contain privately identifiable information that home server admins might not be aware of in the first place. Those log rotation policies are separate from the server-level retention policy, which may be confusing for a novice sysadmin.

Combine this with the federation: even if you trust your home server to do the right thing, the second you join a public room with third-party home servers, those ideas kind of get thrown out because those servers can do whatever they want with that information. Again, a problem that is hard to solve in any federation.

To be fair, IRC doesn't have a great story here either: any client knows not only who's talking to who in a room, but also typically their client IP address. Servers can (and often do) obfuscate this, but often that obfuscation is trivial to reverse. Some servers do provide "cloaks" (sometimes automatically), but that's kind of a "slap-on" solution that actually moves the problem elsewhere: now the server knows a little more about the user.

Overall, I would worry much more about a Matrix home server seizure than a IRC or Signal server seizure. Signal does get subpoenas, and they can only give out a tiny bit of information about their users: their phone number, and their registration, and last connection date. Matrix carries a lot more information in its database.

Amplification attacks on URL previews

I (still!) run an Icecast server and sometimes share links to it on IRC which, obviously, also ends up on (more than one!) Matrix home servers because some people connect to IRC using Matrix. This, in turn, means that Matrix will connect to that URL to generate a link preview.

I feel this outlines a security issue, especially because those sockets would be kept open seemingly forever. I tried to warn the Matrix security team but somehow, I don't think this issue was taken very seriously. Here's the disclosure timeline:

There are a couple of problems here:

  1. the bug was publicly disclosed in September 2020, and not considered a security issue until I notified them, and even then, I had to insist

  2. no clear disclosure policy timeline was proposed or seems established in the project (there is a security disclosure policy but it doesn't include any predefined timeline)

  3. I wasn't informed of the disclosure

  4. the actual solution is a size limit (10MB, already implemented), a time limit (30 seconds, implemented in PR 11784), and a content type allow list (HTML, "media" or JSON, implemented in PR 11936), and I'm not sure it's adequate

  5. (pure vanity:) I did not make it to their Hall of fame

I'm not sure those solutions are adequate because they all seem to assume a single home server will pull that one URL for a little while then stop. But in a federated network, many (possibly thousands) home servers may be connected in a single room at once. If an attacker drops a link into such a room, all those servers would connect to that link all at once. This is an amplification attack: a small amount of traffic will generate a lot more traffic to a single target. It doesn't matter there are size or time limits: the amplification is what matters here.

It should also be noted that clients that generate link previews have more amplification because they are more numerous than servers. And of course, the default Matrix client (Element) does generate link previews as well.

That said, this is possibly not a problem specific to Matrix: any federated service that generates link previews may suffer from this.

I'm honestly not sure what the solution is here. Maybe moderation? Maybe link previews are just evil? All I know is there was this weird bug in my Icecast server and I tried to ring the bell about it, and it feels it was swept under the rug. Somehow I feel this is bound to blow up again in the future, even with the current mitigation.

Moderation

In Matrix like elsewhere, Moderation is a hard problem. There is a detailed moderation guide and much of this problem space is actively worked on in Matrix right now. A fundamental problem with moderating a federated space is that a user banned from a room can rejoin the room from another server. This is why spam is such a problem in Email, and why IRC networks have stopped federating ages ago (see the IRC history for that fascinating story).

The mjolnir bot

The mjolnir moderation bot is designed to help with some of those things. It can kick and ban users, redact all of a user's message (as opposed to one by one), all of this across multiple rooms. It can also subscribe to a federated block list published by matrix.org to block known abusers (users or servers). Bans are pretty flexible and can operate at the user, room, or server level.

Matrix people suggest making the bot admin of your channels, because you can't take back admin from a user once given.

The command-line tool

There's also a new command line tool designed to do things like:

This tool and Mjolnir are based on the admin API built into Synapse.

Rate limiting

Synapse has pretty good built-in rate-limiting which blocks repeated login, registration, joining, or messaging attempts. It may also end up throttling servers on the federation based on those settings.

Fundamental federation problems

Because users joining a room may come from another server, room moderators are at the mercy of the registration and moderation policies of those servers. Matrix is like IRC's +R mode ("only registered users can join") by default, except that anyone can register their own homeserver, which makes this limited.

Server admins can block IP addresses and home servers, but those tools are not easily available to room admins. There is an API (m.room.server_acl in /devtools) but it is not reliable (thanks Austin Huang for the clarification).

Matrix has the concept of guest accounts, but it is not used very much, and virtually no client or homeserver supports it. This contrasts with the way IRC works: by default, anyone can join an IRC network even without authentication. Some channels require registration, but in general you are free to join and look around (until you get blocked, of course).

I have seen anecdotal evidence (CW: Twitter, nitter link) that "moderating bridges is hell", and I can imagine why. Moderation is already hard enough on one federation, when you bridge a room with another network, you inherit all the problems from that network but without the entire abuse control tools from the original network's API...

Room admins

Matrix, in particular, has the problem that room administrators (which have the power to redact messages, ban users, and promote other users) are bound to their Matrix ID which is, in turn, bound to their home servers. This implies that a home server administrators could (1) impersonate a given user and (2) use that to hijack the room. So in practice, the home server is the trust anchor for rooms, not the user themselves.

That said, if server B administrator hijack user joe on server B, they will hijack that room on that specific server. This will not (necessarily) affect users on the other servers, as servers could refuse parts of the updates or ban the compromised account (or server).

It does seem like a major flaw that room credentials are bound to Matrix identifiers, as opposed to the E2E encryption credentials. In an encrypted room even with fully verified members, a compromised or hostile home server can still take over the room by impersonating an admin. That admin (or even a newly minted user) can then send events or listen on the conversations.

This is even more frustrating when you consider that Matrix events are actually signed and therefore have some authentication attached to them, acting like some sort of Merkle tree (as it contains a link to previous events). That signature, however, is made from the homeserver PKI keys, not the client's E2E keys, which makes E2E feel like it has been "bolted on" later.

Availability

While Matrix has a strong advantage over Signal in that it's decentralized (so anyone can run their own homeserver,), I couldn't find an easy way to run a "multi-primary" setup, or even a "redundant" setup (even if with a single primary backend), short of going full-on "replicate PostgreSQL and Redis data", which is not typically for the faint of heart.

How this works in IRC

On IRC, it's quite easy to setup redundant nodes. All you need is:

  1. a new machine (with it's own public address with an open port)

  2. a shared secret (or certificate) between that machine and an existing one on the network

  3. a connect {} block on both servers

That's it: the node will join the network and people can connect to it as usual and share the same user/namespace as the rest of the network. The servers take care of synchronizing state: you do not need to worry about replicating a database server.

(Now, experienced IRC people will know there's a catch here: IRC doesn't have authentication built in, and relies on "services" which are basically bots that authenticate users (I'm simplifying, don't nitpick). If that service goes down, the network still works, but then people can't authenticate, and they can start doing nasty things like steal people's identity if they get knocked offline. But still: basic functionality still works: you can talk in rooms and with users that are on the reachable network.)

User identities

Matrix is more complicated. Each "home server" has its own identity namespace: a specific user (say @anarcat:matrix.org) is bound to that specific home server. If that server goes down, that user is completely disconnected. They could register a new account elsewhere and reconnect, but then they basically lose all their configuration: contacts, joined channels are all lost.

(Also notice how the Matrix IDs don't look like a typical user address like an email in XMPP. They at least did their homework and got the allocation for the scheme.)

Rooms

Users talk to each other in "rooms", even in one-to-one communications. (Rooms are also used for other things like "spaces", they're basically used for everything, think "everything is a file" kind of tool.) For rooms, home servers act more like IRC nodes in that they keep a local state of the chat room and synchronize it with other servers. Users can keep talking inside a room if the server that originally hosts the room goes down. Rooms can have a local, server-specific "alias" so that, say, #room:matrix.org is also visible as #room:example.com on the example.com home server. Both addresses refer to the same room underlying room.

(Finding this in the Element settings is not obvious though, because that "alias" are actually called a "local address" there. So to create such an alias (in Element), you need to go in the room settings' "General" section, "Show more" in "Local address", then add the alias name (e.g. foo), and then that room will be available on your example.com homeserver as #foo:example.com.)

So a room doesn't belong to a server, it belongs to the federation, and anyone can join the room from any serer (if the room is public, or if invited otherwise). You can create a room on server A and when a user from server B joins, the room will be replicated on server B as well. If server A fails, server B will keep relaying traffic to connected users and servers.

A room is therefore not fundamentally addressed with the above alias, instead ,it has a internal Matrix ID, which basically a random string. It has a server name attached to it, but that was made just to avoid collisions. That can get a little confusing. For example, the #fractal:gnome.org room is an alias on the gnome.org server, but the room ID is !hwiGbsdSTZIwSRfybq:matrix.org. That's because the room was created on matrix.org, but the preferred branding is gnome.org now.

As an aside, rooms, by default, live forever, even after the last user quits. There's an admin API to delete rooms and a tombstone event to redirect to another one, but neither have a GUI yet. The latter is part of MSC1501 ("Room version upgrades") which allows a room admin to close a room, with a message and a pointer to another room.

Spaces

Discovering rooms can be tricky: there is a per-server room directory, but Matrix.org people are trying to deprecate it in favor of "Spaces". Room directories were ripe for abuse: anyone can create a room, so anyone can show up in there. It's possible to restrict who can add aliases, but anyways directories were seen as too limited.

In contrast, a "Space" is basically a room that's an index of other rooms (including other spaces), so existing moderation and administration mechanism that work in rooms can (somewhat) work in spaces as well. This enables a room directory that works across federation, regardless on which server they were originally created.

New users can be added to a space or room automatically in Synapse. (Existing users can be told about the space with a server notice.) This gives admins a way to pre-populate a list of rooms on a server, which is useful to build clusters of related home servers, providing some sort of redundancy, at the room -- not user -- level.

Home servers

So while you can workaround a home server going down at the room level, there's no such thing at the home server level, for user identities. So if you want those identities to be stable in the long term, you need to think about high availability. One limitation is that the domain name (e.g. matrix.example.com) must never change in the future, as renaming home servers is not supported.

The documentation used to say you could "run a hot spare" but that has been removed. Last I heard, it was not possible to run a high-availability setup where multiple, separate locations could replace each other automatically. You can have high performance setups where the load gets distributed among workers, but those are based on a shared database (Redis and PostgreSQL) backend.

So my guess is it would be possible to create a "warm" spare server of a matrix home server with regular PostgreSQL replication, but that is not documented in the Synapse manual. This sort of setup would also not be useful to deal with networking issues or denial of service attacks, as you will not be able to spread the load over multiple network locations easily. Redis and PostgreSQL heroes are welcome to provide their multi-primary solution in the comments. In the meantime, I'll just point out this is a solution that's handled somewhat more gracefully in IRC, by having the possibility of delegating the authentication layer.

Delegations

If you do not want to run a Matrix server yourself, it's possible to delegate the entire thing to another server. There's a server discovery API which uses the .well-known pattern (or SRV records, but that's "not recommended" and a bit confusing) to delegate that service to another server. Be warned that the server still needs to be explicitly configured for your domain. You can't just put:

{ "m.server": "matrix.org:443" }

... on https://example.com/.well-known/matrix/server and start using @you:example.com as a Matrix ID. That's because Matrix doesn't support "virtual hosting" and you'd still be connecting to rooms and people with your matrix.org identity, not example.com as you would normally expect. This is also why you cannot rename your home server.

The server discovery API is what allows servers to find each other. Clients, on the other hand, use the client-server discovery API: this is what allows a given client to find your home server when you type your Matrix ID on login.

Performance

The high availability discussion brushed over the performance of Matrix itself, but let's now dig into that.

Horizontal scalability

There were serious scalability issues of the main Matrix server, Synapse, in the past. So the Matrix team has been working hard to improve its design. Since Synapse 1.22 the home server can horizontally scale to multiple workers (see this blog post for details) which can make it easier to scale large servers.

Other implementations

There are other promising home servers implementations from a performance standpoint (dendrite, Golang, entered beta in late 2020; conduit, Rust, beta; others), but none of those are feature-complete so there's a trade-off to be made there. Synapse is also adding a lot of feature fast, so it's an open question whether the others will ever catch up. (I have heard that Dendrite might actually surpass Synapse in features within a few years, which would put Synapse in a more "LTS" situation.)

Latency

Matrix can feel slow sometimes. For example, joining the "Matrix HQ" room in Element (from matrix.debian.social) takes a few minutes and then fails. That is because the home server has to sync the entire room state when you join the room. There was promising work on this announced in the lengthy 2021 retrospective, and some of that work landed (partial sync) in the 1.53 release already. Other improvements coming include sliding sync, lazy loading over federation, and fast room joins. So that's actually something that could be fixed in the fairly short term.

But in general, communication in Matrix doesn't feel as "snappy" as on IRC or even Signal. It's hard to quantify this without instrumenting a full latency test bed (for example the tools I used in the terminal emulators latency tests), but even just typing in a web browser feels slower than typing in a xterm or Emacs for me.

Even in conversations, I "feel" people don't immediately respond as fast. In fact, this could be an interesting double-blind experiment to make: have people guess whether they are talking to a person on Matrix, XMPP, or IRC, for example. My theory would be that people could notice that Matrix users are slower, if only because of the TCP round-trip time each message has to take.

Transport

Some courageous person actually made some tests of various messaging platforms on a congested network. His evaluation was basically:

So that was interesting. I suspect IRC would have also fared better, but that's just a feeling.

Other improvements to the transport layer include support for websocket and the CoAP proxy work from 2019 (targeting 100bps links), but both seem stalled at the time of writing. The Matrix people have also announced the pinecone p2p overlay network which aims at solving large, internet-scale routing problems. See also this talk at FOSDEM 2022.

Usability

Onboarding and workflow

The workflow for joining a room, when you use Element web, is not great:

  1. click on a link in a web browser
  2. land on (say) https://matrix.to/#/#matrix-dev:matrix.org
  3. offers "Element", yeah that's sounds great, let's click "Continue"
  4. land on https://app.element.io/#/room%2F%23matrix-dev%3Amatrix.org and then you need to register, aaargh

As you might have guessed by now, there is a specification to solve this, but web browsers need to adopt it as well, so that's far from actually being solved. At least browsers generally know about the matrix: scheme, it's just not exactly clear what they should do with it, especially when the handler is just another web page (e.g. Element web).

In general, when compared with tools like Signal or WhatsApp, Matrix doesn't fare so well in terms of user discovery. I probably have some of my normal contacts that have a Matrix account as well, but there's really no way to know. It's kind of creepy when Signal tells you "this person is on Signal!" but it's also pretty cool that it works, and they actually implemented it pretty well.

Registration is also less obvious: in Signal, the app confirms your phone number automatically. It's friction-less and quick. In Matrix, you need to learn about home servers, pick one, register (with a password! aargh!), and then setup encryption keys (not default), etc. It's a lot more friction.

And look, I understand: giving away your phone number is a huge trade-off. I don't like it either. But it solves a real problem and makes encryption accessible to a ton more people. Matrix does have "identity servers" that can serve that purpose, but I don't feel confident sharing my phone number there. It doesn't help that the identity servers don't have private contact discovery: giving them your phone number is a more serious security compromise than with Signal.

There's a catch-22 here too: because no one feels like giving away their phone numbers, no one does, and everyone assumes that stuff doesn't work anyways. Like it or not, Signal forcing people to divulge their phone number actually gives them critical mass that means actually a lot of my relatives are on Signal and I don't have to install crap like WhatsApp to talk with them.

5 minute clients evaluation

Throughout all my tests I evaluated a handful of Matrix clients, mostly from Flathub because almost none of them are packaged in Debian.

Right now I'm using Element, the flagship client from Matrix.org, in a web browser window, with the PopUp Window extension. This makes it look almost like a native app, and opens links in my main browser window (instead of a new tab in that separate window), which is nice. But I'm tired of buying memory to feed my web browser, so this indirection has to stop. Furthermore, I'm often getting completely logged off from Element, which means re-logging in, recovering my security keys, and reconfiguring my settings. That is extremely annoying.

Coming from Irssi, Element is really "GUI-y" (pronounced "gooey"). Lots of clickety happening. To mark conversations as read, in particular, I need to click-click-click on all the tabs that have some activity. There's no "jump to latest message" or "mark all as read" functionality as far as I could tell. In Irssi the former is built-in (alt-a) and I made a custom /READ command for the latter:

/ALIAS READ script exec \$_->activity(0) for Irssi::windows

And yes, that's a Perl script in my IRC client. I am not aware of any Matrix client that does stuff like that, except maybe Weechat, if we can call it a Matrix client, or Irssi itself, now that it has a Matrix plugin (!).

As for other clients, I have looked through the Matrix Client Matrix (confusing right?) to try to figure out which one to try, and, even after selecting Linux as a filter, the chart is just too wide to figure out anything. So I tried those, kind of randomly:

Unfortunately, I lost my notes on those, I don't actually remember which one did what. I still have a session open with Mirage, so I guess that means it's the one I preferred, but I remember they were also all very GUI-y.

Maybe I need to look at weechat-matrix or gomuks. At least Weechat is scriptable so I could continue playing the power-user. Right now my strategy with messaging (and that includes microblogging like Twitter or Mastodon) is that everything goes through my IRC client, so Weechat could actually fit well in there. Going with gomuks, on the other hand, would mean running it in parallel with Irssi or ... ditching IRC, which is a leap I'm not quite ready to take just yet.

Oh, and basically none of those clients (except Nheko and Element) support VoIP, which is still kind of a second-class citizen in Matrix. It does not support large multimedia rooms, for example: Jitsi was used for FOSDEM instead of the native videoconferencing system.

Bots

This falls a little aside the "usability" section, but I didn't know where to put this... There's a few Matrix bots out there, and you are likely going to be able to replace your existing bots with Matrix bots. It's true that IRC has a long and impressive history with lots of various bots doing various things, but given how young Matrix is, there's still a good variety:

One thing I haven't found an equivalent for is Debian's MeetBot. There's an archive bot but it doesn't have topics or a meeting chair, or HTML logs.

Working on Matrix

As a developer, I find Matrix kind of intimidating. The specification is huge. The official specification itself looks somewhat digestable: it's only 6 APIs so that looks, at first, kind of reasonable. But whenever you start asking complicated questions about Matrix, you quickly fall into the Matrix Spec Change specification (which, yes, is a separate specification). And there are literally hundreds of MSCs flying around. It's hard to tell what's been adopted and what hasn't, and even harder to figure out if your specific client has implemented it.

(One trendy answer to this problem is to "rewrite it in rust": Matrix are working on implementing a lot of those specifications in a matrix-rust-sdk that's designed to take the implementation details away from users.)

Just taking the latest weekly Matrix report, you find that three new MSCs proposed, just last week! There's even a graph that shows the number of MSCs is progressing steadily, at 600+ proposals total, with the majority (300+) "new". I would guess the "merged" ones are at about 150.

That's a lot of text which includes stuff like 3D worlds which, frankly, I don't think you should be working on when you have such important security and usability problems. (The internet as a whole, arguably, doesn't fare much better. RFC600 is a really obscure discussion about "INTERFACING AN ILLINOIS PLASMA TERMINAL TO THE ARPANET". Maybe that's how many MSCs will end up as well, left forgotten in the pits of history.)

And that's the thing: maybe the Matrix people have a different objective than I have. They want to connect everything to everything, and make Matrix a generic transport for all sorts of applications, including virtual reality, collaborative editors, and so on.

I just want secure, simple messaging. Possibly with good file transfers, and video calls. That it works with existing stuff is good, and it should be federated to remove the "Signal point of failure". So I'm a bit worried with the direction all those MSCs are taking, especially when you consider that clients other than Element are still struggling to keep up with basic features like end-to-end encryption or room discovery, never mind voice or spaces...

Conclusion

Overall, Matrix is somehow in the space XMPP was a few years ago. It has a ton of features, pretty good clients, and a large community. It seems to have gained some of the momentum that XMPP has lost. It may have the most potential to replace Signal if something bad would happen to it (like, I don't know, getting banned or going nuts with cryptocurrency)...

But it's really not there yet, and I don't see Matrix trying to get there either, which is a bit worrisome.

Looking back at history

I'm also worried that we are repeating the errors of the past. The history of federated services is really fascinating:. IRC, FTP, HTTP, and SMTP were all created in the early days of the internet, and are all still around (except, arguably, FTP, which was removed from major browsers recently). All of them had to face serious challenges in growing their federation.

IRC had numerous conflicts and forks, both at the technical level but also at the political level. The history of IRC is really something that anyone working on a federated system should study in detail, because they are bound to make the same mistakes if they are not familiar with it. The "short" version is:

(The numbers were taken from the Wikipedia page and Netsplit.de. Note that I also include other networks launch in parenthesis for context.)

Pretty dramatic, don't you think? Eventually, somehow, IRC became irrelevant for most people: few people are even aware of it now. With less than a million users active, it's smaller than Mastodon, XMPP, or Matrix at this point.1 If I were to venture a guess, I'd say that infighting, lack of a standardization body, and a somewhat annoying protocol meant the network could not grow. It's also possible that the decentralised yet centralised structure of IRC networks limited their reliability and growth.

But large social media companies have also taken over the space: observe how IRC numbers peak around the time the wave of large social media companies emerge, especially Facebook (2.9B users!!) and Twitter (400M users).

Where the federated services are in history

Right now, Matrix, and Mastodon (and email!) are at the "pre-EFnet" stage: anyone can join the federation. Mastodon has started working on a global block list of fascist servers which is interesting, but it's still an open federation. Right now, Matrix is totally open, but matrix.org publishes a (federated) block list of hostile servers (#matrix-org-coc-bl:matrix.org, yes, of course it's a room).

Interestingly, Email is also in that stage, where there are block lists of spammers, and it's a race between those blockers and spammers. Large email providers, obviously, are getting closer to the EFnet stage: you could consider they only accept email from themselves or between themselves. It's getting increasingly hard to deliver mail to Outlook and Gmail for example, partly because of bias against small providers, but also because they are including more and more machine-learning tools to sort through email and those systems are, fundamentally, unknowable. It's not quite the same as splitting the federation the way EFnet did, but the effect is similar.

HTTP has somehow managed to live in a parallel universe, as it's technically still completely federated: anyone can start a web server if they have a public IP address and anyone can connect to it. The catch, of course, is how you find the darn thing. Which is how Google became one of the most powerful corporations on earth, and how they became the gatekeepers of human knowledge online.

I have only briefly mentioned XMPP here, and my XMPP fans will undoubtedly comment on that, but I think it's somewhere in the middle of all of this. It was co-opted by Facebook and Google, and both corporations have abandoned it to its fate. I remember fondly the days where I could do instant messaging with my contacts who had a Gmail account. Those days are gone, and I don't talk to anyone over Jabber anymore, unfortunately. And this is a threat that Matrix still has to face.

It's also the threat Email is currently facing. On the one hand corporations like Facebook want to completely destroy it and have mostly succeeded: many people just have an email account to register on things and talk to their friends over Instagram or (lately) TikTok (which, I know, is not Facebook, but they started that fire).

On the other hand, you have corporations like Microsoft and Google who are still using and providing email services — because, frankly, you still do need email for stuff, just like fax is still around — but they are more and more isolated in their own silo. At this point, it's only a matter of time they reach critical mass and just decide that the risk of allowing external mail coming in is not worth the cost. They'll simply flip the switch and work on an allow-list principle. Then we'll have closed the loop and email will be dead, just like IRC is "dead" now.

I wonder which path Matrix will take. Could it liberate us from these vicious cycles?

Update: this generated some discussions on lobste.rs.


  1. According to Wikipedia, there are currently about 500 distinct IRC networks operating, on about 1,000 servers, serving over 250,000 users. In contrast, Mastodon seems to be around 5 million users, Matrix.org claimed at FOSDEM 2021 to have about 28 million globally visible accounts, and Signal lays claim to over 40 million souls. XMPP claims to have "millions" of users on the xmpp.org homepage but the FAQ says they don't actually know. On the proprietary silo side of the fence, this page says

    • Facebook: 2.9 billion users
    • WhatsApp: 2B
    • Instagram: 1.4B
    • TikTok: 1B
    • Snapchat: 500M
    • Pinterest: 480M
    • Twitter: 397M

    Notable omission from that list: Youtube, with its mind-boggling 2.6 billion users...

    Those are not the kind of numbers you just "need to convince a brother or sister" to grow the network...

Some comments and whatnot from another Montréaler

Hello there. Some comments from an active Matrix user (aussi un Montréalais, but I don't work for matrix.org or New Vector), from top to bottom. (For other readers: they're AFAIK so please correct me if necessary.)

Element 2.2.1: mentions many more third parties

Writing all the third parties together is quite misleading and you should definitely separate them. Specifically, according to my understanding of the text:

  • Twillo, if you register with a phone number on an EMS-operated homeserver
  • Stripe and Quaderno if you're a paying customer
  • LinkedIn, Twitter, Google, Outplay, Salesforce, and Pipedrive if you click on an ad of Element from a third-party platform (presumably they're not used if you land on Element directly, so maybe they shouldn't be included)
  • Hubspot, Matomo (selfhosted) and Posthog for website analytics

So I don't think they're applicable to the client.

Whether privacy policies are actually followed is a different thing, but assumptions need to be clearly indicated, in my opinion.

As an aside, I also appreciate that Matrix.org has a fairly decent code of conduct

The enforcement of it (bans in #matrix-org-coc-bl:matrix.org whose reason is code of conduct violations) is commonly believed to be dubious at times. Specifically, they ban people (including those not exhibiting bad faith) too easily (often without warning) and there are no real appeal process (AFAIK abuse@matrix.org doesn't manually respond to most emails). Since #matrix-org-coc-bl:matrix.org is also used outside of official Matrix rooms (it applies to public communities directly related to EMS-operated homeservers as well, eg. FOSDEM, Arch Linux, etc.), there definitely should be some constraints w/r/t the use of bans.

Third-party homeservers seem to be much better moderated.

The mjolnir bot

Unfortunately, in practice, Mjolnir requires a homeserver to be run (given that the bot expects to be free of ratelimit, which requires an exception in the homeserver, which is unlikely to be granted to someone who's not related to the homeserver's administration). This makes it inaccessible to people who cannot run a homeserver (and cannot trust one who can to handle moderation). See also here.

Server admins can block IP addresses and home servers, but those tools are not currently available to room admins.

Room admins can block homeservers through ACL, it's not intuitive (/devtools => Explore Room State => m.room.server_acl) but it is indeed available. But ACL itself is not reliable.

Also, Mjolnir user bans support wildcard (@*:example.com).

Matrix has the concept of guest accounts, but it is not used very much, and virtually no client supports it.

Element does, but virtually no homeserver supports it (since it is easily abusable).

as servers could refuse parts of the updates

pretty sure you can't do that without affecting all future updates

I have heard anecdotal evidence that "moderating bridges is hell"

Since bridge puppets are still users, you could ban them or redact their messages. If the platform can be accessed through multiple bridges running the same bridge software, you could use Mjolnir to ban @bridge_username:* with the server name as wildcard. Of course, that doesn't prevent the situation where multiple public bridges exist that run different software and do not require explicit approval (eg. Bifrost for XMPP), but that's rare.

and then that room will be available on your example.com homeserver as #foo:example.com

But the room is already available as, say, #foo:matrix.org, and if that is the selected main alias then that's what's gonna be shown even when you add the room to example.com's room directory. So local aliases are only for someone on your homeserver to link this room, and non-main public aliases are only for someone on any homeserver to link this room, which means neither have any actual uses other than 1. vanity, and 2. to act as a redundancy in case all other public aliases fail (due to homeserver outage).

tombstone event

It does have a GUI in Element:

  • /upgraderoom
  • For rooms before version 9, room settings => Security & Privacy => "Space members" has an "upgrade required" which is clickable if you have the permission to upgrade it (IIRC)

but Matrix.org people are trying to deprecate it in favor of "Spaces"

Citation required. Also Spaces are rooms and so they can also be included in room directories.

New users can be added to a space or room automatically in Synapse

In public homeservers, this may leak account age.

It's possible to restrict who can add aliases

Only public aliases (local aliases are unrestricted afaik). Also they're not required for listing on room directories.

I have heard that Dendrite might actually surpass Synapse in features within a few years

Given that this is a thing, it is likely to be the goal.

In Matrix, you need to learn about home servers, pick one,

How Element markets effectively forces everyone onto matrix.org (or EMS) and that's a problem

register (with a password! aargh!)

Don't you also have a password on Signal?

but I don't feel confident sharing my phone number there

You could share email addresses, but yes, I get your point.

Use of identity servers became opt-in in late? 2020 amid concerns that it makes Riot.im (then) a spyware by forcing a call-home. In fact a selling point of Matrix is the non-requirement of email or phone number (if applicable; but it is obvious that this will lead to abuse).

It does not support large multimedia rooms

Rooms with more than 2 users don't have native VoIP yet.

Working on Matrix

That's what happens when the same people effectively own both the protocol and the first client... But then you said of IRC, that

If I were to venture a guess, I'd say that infighting, lack of a standardization body, and a somewhat annoying protocol meant the network could not grow.

So it could also be an advantage that Matrix has a standardization body from the get-go (whether the body itself is good is a different question).

I just want secure, simple messaging. Possibly with good file transfers, and video calls.

I don't think that has been Matrix's goal from the get-go, though you could say they're now working towards that.

For me, Matrix is still only for two purposes:

  1. For individuals, to run a community (replacing Telegram and Discord), and
  2. For organizational communication (replacing Slack and MS Teams).

Sure, interoperability (which Matrix has probably lobbied for), but the cost of bridging is still quite high.

Mastodon has started working on a global block list of fascist servers

Some (certainly not mainstream) consider "not blocking abusive servers" as grounds for blocking so it's already happening on the fediverse.

but matrix.org publishes a (federated) block list of hostile servers

Element effectively encourages the use of blocklists, so abuse of which will bound to happen. Look, of course I support having people choosing their own moderation policy, but that only works in theory: in practice greater power does not lead to greater responsibility.

Comment by Austin Huang
some responses

Allo!

So first off, I should note that I actually put some poor Matrix.org through the pain of reading a draft of this article before publishing it, so I consider it somewhat accurate, or at least as much as reasonably possible considering the sheer size of the thing.

Now, as to your specific comments...

Writing all the third parties together is quite misleading and you should definitely separate them.

My reviewer also had that objection, but I will point out that the distinction is not made in the privacy policy. So I think it would actually be unfair to split it out here: it's not like you can actually pick and choose which part of the privacy policy you accept when you start using Matrix services.

In fact I'd even say it's a problem that all of those are indiscrimenatly present in the policy.

As an aside, I also appreciate that Matrix.org has a fairly decent code of conduct

[response summary: they ban people too easily]

I err on the side of banning more people than less, to be honest, so I'm perfectly fine with this. Maybe it would be better to have two rooms, one for explicit code violations and one, more "liberal" room where anything goes?

You also made comments regarding Mastodon and moderation policies which I don't quite grasp the point of.

[...]

Thanks for the clarifications on Mjolnir, room blocking, and guest accounts, I updated the article accordingly.

tombstone event

It does have a GUI in Element:

  • /upgraderoom

That's literally not a GUI: it's a text command.

but Matrix.org people are trying to deprecate it in favor of "Spaces"

Citation required. Also Spaces are rooms and so they can also be included in room directories.

The reviewer didn't wish to be cited, so I can't actually provide a quote here. Happy to stand corrected, but it does feel like a large feature overlap, no?

New users can be added to a space or room automatically in Synapse

In public homeservers, this may leak account age.

Considering the entire history of everything is available forever on home servers, that seems like a minor compromise to get higher room availability in a distributed cluster (which is one of my use cases, that, granted, I did not make very clear).

Only public aliases (local aliases are unrestricted afaik). Also they're not required for listing on room directories.

Now I'm even more confused than I was before. Local addresses, aliases, public aliases, wtf?

Given that this is a thing, it is likely to be the goal.

added a link.

register (with a password! aargh!)

Don't you also have a password on Signal?

Not really. They really want you to set a PIN so that you can do account recovery when you lose your phone, but I am not sure it's mandatory. Even if it was, it's not something you get prompted for all the time, only when you lose a device. In Element, I frequently had to login again, including in the Android app. I never had to use my Signal PIN so far (although for a while they used to prompt for it so that you wouldn't forget it, but they thankfully stopped that annoying practice).

Thanks for the review!

Comment by anarcat
Created . Edited .