Comments URL: https://news.ycombinator.com/item?id=47310169

Points: 5

# Comments: 0

Auth for clients is also specified in the spec - there is some scope for homeservers to freestyle, but nowadays they have to implement OIDC: https://spec.matrix.org/latest/client-server-api/#client-aut...

Whereas I literally select count(*)'d from the destinations table on matrix.org, filtered on servers which had been federating in the last week(?) in order to get the specific stats above. (And then count(*) of all time for the 150K figure).

The problem is more that Element team is seriously stretched (particularly after the various misadventures outlined here: https://youtu.be/lkCKhP1jxdk?t=740) - so even if there was a pot of money to (say) merge custom emoji PRs... the team is more than overloaded already with commitments to folks like NATO and the UN. Meanwhile, onboarding new folks and figuring out how to do the Discordy features and launch a separately Discordy app under a Discordy server would also be a major distraction from ensuring Element gets sustainable by selling govtech messaging solutions.

So, we're caught in a catch-22 for now. One solution would be for other projects to build Discordy solutions on top of Matrix (like Cinny or Commet), or fork Element to be more Discordy (and run their own crowdfunders, perhaps in conjunction with The Matrix Foundation). Otherwise, we have to wait for Element to get sustainable via govtech work so it can eventually think about diversifying back into consumer apps.

The difference with Discord is that Matrix is a protocol, not a service. It's made up of thousands of servers run by different people in different countries. Public instances may choose to verify users in affected countries to abide by the law; others may choose to run a private instance instead.

19. "media downloads are unauthenticated by default" -> fixed in Jun 2024: https://matrix.org/blog/2024/06/26/sunsetting-unauthenticate...

20. "ask someone else’s homeserver to replicate media" -> also fixed by authenticated media

21. "media uploads are unverified by default" - for E2EE this is very much a feature; running file transfers through an antivirus scanner would break E2EE. (Some enterprisey clients like Element Pro do offer scanning at download, but you typically wouldn't want to do it at upload given by the time people download the AV defs might be stale). For non-encrypted media, content can and is scanned on upload - e.g. by https://github.com/matrix-org/synapse-spamcheck-badlist

22. "all it takes is for one of your users to request media from an undesirable room for your homeserver to also serve up copies of it" - yes, this is true. similarly, if you host an IMAP server for your friends, and one of them gets spammed with illegal content, it unfortunately becomes your problem.

In terms of "invisible events in rooms can somehow download abusive content onto servers and clients" - I'm not aware of how that would work. Clients obviously download media when users try to view it; if the event is invisible then the client won't try to render it and won't try to download the media.

Nowadays many clients hide media in public rooms, so you have to manually click on the blurhash to download the file to your server anyway.

> isn't Matrix based out of the UK and primary hosted instances on AWS in the UK?

It doesn't matter what country you run your server in or where your company is based; if you're providing public signup to a chat server then the countries (UK, AU, NZ etc) which require age verification will object if you don't age verify the users from those countries. (This is why Discord is doing it, despite being US HQ'd). In other words, the fact that The Matrix.org Foundation happens to be UK HQ'd doesn't affect the situation particularly.

(Edit: also, as others have pointed out, Matrix is a protocol, not a service or a product. The Matrix Foundation is effectively a standards body which happens to run the matrix.org server instance, but the jurisdiction that the standards body is incorporated in makes little difference - just like IETF being US-based doesn't mean the Internet is actually controlled by the US govt).

> Their solution is for everyone to pay for Matrix with a credit card to verify age.

Verifying users in affected countries based on owning a credit card is one solution we're proposing; suspect there will be other ways to do so too. However: this would only apply on the matrix.org server instance. Meanwhile, there are 23,306 other servers currently federating with matrix.org (out of a total of 156,055) - and those other servers, if they provide public signup, can figure out how to solve the problem in their own way.

Also, the current plan on the matrix.org server is to only verify users who are in affected countries (as opposed to try to verify the whole userbase as Discord is).

However, in practice, this was not exploitable: the only way to exercise these primitives was over the network, where network latency and request rate limiting mitigates such attacks.

Meanwhile, we had already rewritten and replaced libolm with vodozemac, a pure rust implementation using robust primitives, shipped in the major Matrix SDKs and implementations like Element and Element X.

I’m not sure this counts as alarmingly cavalier. I do regret libolm ever going into production with substandard primitives from a hygiene perspective, but we fixed it as soon as we could via vodozemac, and meanwhile included the safety warning.

matui looks super fun - you should come tell https://matrix.to/#/#twim:matrix.org about it :)

It entirely depends on the client. There is nothing in the protocol which means that clients have to store old keys, but many do - mainly so they have a copy that can be backed up on the server to support migrating between devices, and for history sharing, as you say. However you absolutely could configure a locked-down Matrix client which discards megolm keys after receipt.

> My understanding is that, while a _sender_ will rotate Megolm sessions every 100 or so messages, recipients tend not to: clients will accept ciphertexts sent from those old sessions for an indefinite period of time. Again, I haven't been following developments in the Matrix world for a little while, so please correct me if I'm wrong.

Yup, this is fair - and agreed that implementations could and should discard unexpected messages in those sessions. There's nothing in the protocol that stops that (but also it's not explicitly covered in the spec).

We can fix this though; thanks for flagging it (and sorry if we missed it in the RHUL research...)