forked from quentin/quentin.dufour.io
86 lines
4.1 KiB
Markdown
86 lines
4.1 KiB
Markdown
---
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layout: post
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slug: matrix-migrate-encrypted-room-to-a-clear-text-one
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status: published
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sitemap: true
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title: "Matrix: Migrate an encrypted room to a clear text one"
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description: Matrix E2EE does not work well with public roooms
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category: operation
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tags:
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---
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Some time ago, the Matrix team was pushing hard E2EE and activated it for all created rooms.
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Believing encryption was the future, we kept this default for all of our rooms.
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But now that one of our room starts being popular, it appears that E2EE does not work well with public rooms:
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1. the history is not available to newcomers
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2. we can not search the history of an encrypted room (or at least, I never managed to make it work even with the desktop app)
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3. notification options are more limited
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4. scaling issues
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5. many additional minor issues
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It seems that Matrix developers are aware of these problems as if you create a "public room" now, you will not be proposed to encrypt it.
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But for existing rooms, we still have a problem: for security reasons, you can't disable encryption in a room.
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Our only option is to create a new room and to point the old one to the new one.
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Thankfully, Matrix has a feature named **Tombstone** that helps redirecting users from one room to another.
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This feature is used for room version upgrade, but we can "abuse" it to redirect people to a completely different room.
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First, you must create a new clear text room.
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To provide the best experience to your users, take time to configure its picture, description, and so on.
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Now, go to your old room, remove all its aliases to be able to set them on the new room.
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You can set a new alias for your old room and send a message containing it on your new room, to "connect it with the old one", eg:
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> Hi, this is the beginning of the history of this room. If you want to go back even more in time, check the old room: #myroom-old:example.tld
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Finally, you need the identifier of your **new** room. It starts with a `!`. For example: `!ARbIZeDKGloDOnjyyw:deuxfleurs.fr`.
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Keep it somewhere accessible, and we are done configuring our new room.
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We can now prepare the tombstone for the old room.
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First, you should inform your users with a message, something like:
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> Hi @room, we are migrating to a new room to fix some issues with this one.
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You will not be able to post new messages here, please follow the provided redirection to join the new room.
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Sorry for the inconvenience.
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Now we will prepare a **state event** that point to the **new** room, create a file named `migration.json`
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based on the following template:
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```json
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{
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"body": "We migrated to a cleartext rooms as E2EE does not work well with large public rooms",
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"replacement_room": "!ARbIZeDKGloDOnjyyw:deuxfleurs.fr"
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}
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```
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This event must be sent in the **old** room. Let's say its identifier is `!MFnHRRrCTMeHvfnNUD:deuxfleurs.fr`.
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The URL template is thus:
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```
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https://im.deuxfleurs.fr/_matrix/client/v3/rooms/!MFnHRRrCTMeHvfnNUD:deuxfleurs.fr/state/m.room.tombstone
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```
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The last thing we need is to build an header file containing the required information for authentication onto the API.
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Create a file named `hdrs.txt` based on the following template.
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```text
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Authorization: Bearer see_below_how_you_can_find_me
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Content-Type: application/json
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```
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*The authorization header can be extracted from an Element Web instance by opening the developer panel (F12) and going to the Network tab.
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Then select a request going to your matrix backend, on the right part of your screen search the "Authorization" line and copy/paste its value.*
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Finally you can send the request to the API by again adapting the following command template:
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```bash
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curl \
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-H @hdrs.txt \
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-X PUT \
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-d @migration.json \
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'https://im.deuxfleurs.fr/_matrix/client/v3/rooms/!MFnHRRrCTMeHvfnNUD:deuxfleurs.fr/state/m.room.tombstone'
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```
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And that's all, you have migrated your old encrypted room to a new clear text one!
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If you want to explore all the possibilities offered by the developer tools, you can read [Matrix specification](https://spec.matrix.org/).
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For example, our tombstone event is documented here: [`m.room.tombstone`](https://spec.matrix.org/v1.2/client-server-api/#mroomtombstone)
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