New post about matrix migration

Gemfile.lock

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_posts/2022-03-24-matrix-migrate-encrypted-room-to-a-clear-text-one.md

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+---
+layout: post
+slug: matrix-migrate-encrypted-room-to-a-clear-text-one
+status: published
+sitemap: true
+title: "Matrix: Migrate an encrypted room to a clear text one"
+description: Matrix E2EE does not work well with public roooms
+category: operation
+tags:
+---
+
+Some time ago, the Matrix team was pushing hard E2EE and activated for all created rooms.
+Believing encryption was the future, we kept this default for all the rooms we created.
+But now that one of our room starts being popular, it appeares that E2EE does not work well with public rooms:
+  1. the history is not available to newcomers
+  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)
+  3. notifications options are limited on mobile
+  4. scaling issues
+  5. and so on.
+
+It seems that Matrix developpers are aware of these problems as now, if you create a "public room", you will not be asked to encrypt it at all.
+But for existing rooms, we have a problem: for security reasons, you can't disable encryption in a room.
+Our only option is to create a new room and to point the old one to the new one.
+Thankfully, Matrix has a feature named **Tombstone** that helps redirecting users from one room to another.
+This feature is used for room version upgrade, but we can "abuse" it to redirect people to a completely different room.
+
+First, you must create a new clear text room.
+To provide the best experience to your users, take time to configure its picture, description, and so on.
+Now, go to your old room, remove all its aliases to be able to set them on the new room.
+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:
+
+> 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
+
+Finally, you need the identifier of your room. It starts with a `!`. For example: `!ARbIZeDKGloDOnjyyw:deuxfleurs.fr`.
+Keep it somewhere accessible, and we are done configuring our new room.
+
+We can now prepare the tombstone for the old room.
+First, you should inform your users with a message, something like:
+
+> Hi @room, we are migrating to a new room to fix some issues with this one. 
+You will not be able to post new messages here, please follow the provided redirection to join the new room. 
+Sorry for the inconvenience.
+
+Now, open the developper tools in your old room by typing in the message box:
+
+```
+/devtools
+```
+
+*You can also open it by going in "Room Settings" -> "Advanced" -> "Open Devtools"*
+
+A window must appear. Click on "Send Custom Event". Then click on the red button "Event" to create a "State Event".
+Put `m.room.tombstone` as the Event Type, keep the State Key field empty, and finally enter the following content (replace the example room ID by the one of your new room):
+
+```json
+{
+  "body": "We migrated to a cleartext rooms as E2EE does not work well with large public rooms",
+  "replacement_room": "!ARbIZeDKGloDOnjyyw:deuxfleurs.fr"
+}
+```
+
+And that's all, you have migrated your old encrypted room to a new clear text one!
+
+If you want to explore all the possibilities offered by the developer tools, you can read [Matrix specification](https://spec.matrix.org/).
+For example, our tombstone event is documented here: [`m.room.tombstone`](https://spec.matrix.org/v1.2/client-server-api/#mroomtombstone)