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Matrix Metadata Problem: the server sees everything except your messages (dfrws.org)
submitted 3 days ago* (last edited 2 days ago) by to c/matrix@lemmy.ml
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Matrix Metadata Problem: the server sees everything except your messages

People pick Matrix because of end-to-end encryption. But E2EE only protects message content — everything around it is plaintext.

The server sees:

  • Your ID, IP, client type and version, device you use
  • Your presence, typing status, read receipts
  • Which rooms you join and when you join/leave
  • Who else is in those rooms → your entire social graph
  • Room names, topics, avatars (all plaintext state)
  • For every message: who sent it, which room, a millisecond timestamp, type, size

And federation copies most of that to every other server whose users are in the room. Your "social footprint" isn't one copy — it's as many as there are servers.

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[–] [S] 3 points 2 days ago (4 children)

Matrix can expose your device name and device details to other homeservers through federation. Profile information such as your avatar and bio can also be queried remotely. A client version is not a dedicated federation field, but it can leak through the device name. Signal at least has Sealed Sender, which hides the sender's identity from its own service in supported cases.

This is about metadata, not centralisation, self-hosting, or phone-number registration. Those are separate issues, not trade-offs.

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  • [–] 2 points 2 days ago (3 children)

    Those are absolutely trade-offs. Do you want the app to positively ID you and tie you to your passport, or do you want the app to broadcast your set name and set identity strings to those you opt in to share it with?

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  • [–] [S] 2 points 2 days ago (2 children)

    You haven’t explained why I have to choose between these two trade-offs. I want neither: I want strong metadata protection without being forced to link my account to my real-world identity.

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  • [–] 2 points 1 day ago (1 child)

    I'm replying to your statement. You proposed Signal as a point of comparison, so those are the apps to compare. They're both less than perfect if your only metric is anonymity, but their shortcomings are very different, and the shortcomings of Signal are fundamentally de-anonymising whereas Matrix is just metadata rich. But you can set your own client string, your username, your avatar, it's all information you inputted (either as a user or app developer). With Signal, the data that's shared is all controlled by Signal.

    I'm not defending Matrix. If the design decisions of Matrix aren't what you want, then there's room to ask for or build an alternative. If Matrix or discourse around Matrix is misleading about what is shared then that's a good thing to highlight.

    What I meant with my reply was to contrast it with Signal and communicate that Signal isn't a valid alternative. It's not the same class of service. Matrix exists to facilitate chatting with friends and Signal exists to conduct surveillance on you and your friends.

    You don't have to choose between these two trade-offs. I'm not saying a third system can't be better. But any third system wasn't being evaluated in the thread I replied to.

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