MSC4266: Policies in /.well-known/matrix/support

Signed-off-by: Johannes Marbach <[email protected]>

proposals/4266-policies.md

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+# MSC4266: Policies in `/.well-known/matrix/support`
+
+Matrix supports collecting policy consent from users during [account
+registration]. There is, however, no API allowing clients to retrieve the
+policies again at a later point. This requires the user to manually store them
+upon registration to be able to refer to them again.
+
+Furthermore, some policies, such as the privacy policy, might be relevant for
+users of other homeservers. Again, these users' clients have no way to
+programmatically retrieve the server's policies.
+
+The present proposal addresses this situation by publishing the policies in the
+server's support document under [`/.well-known/matrix/support`].
+
+## Proposal
+
+A new optional property `policies` is added to the response of
+[`/.well-known/matrix/support`]. The format is the same one used during
+[registration][account registration].
+
+``` json5
+{
+  "contacts": [ ... ],
+  "support_page": ...,
+  "policies": {
+    "privacy_policy": {
+      "en": {
+        "name": "Privacy Policy",
+        "url": "https://example.org/somewhere/privacy-1.2-en.html"
+      },
+      "fr": {
+        "name": "Politique de confidentialité",
+        "url": "https://example.org/somewhere/privacy-1.2-fr.html"
+      },
+      "version": "1.2"
+    },
+    "terms_of_service": {
+      "en": {
+        "name": "Terms of Service",
+        "url": "https://example.org/somewhere/terms-1.2-en.html"
+      },
+      "fr": {
+        "name": "Conditions d'utilisation",
+        "url": "https://example.org/somewhere/terms-1.2-fr.html"
+      },
+      "version": "1.2"
+    }
+  }
+}
+```
+
+If the request is authenticated, the server SHOULD respond with the latest
+version of the policies that the user consented to.
+
+## Potential issues
+
+None.
+
+## Alternatives
+
+It might be debatable whether policies represent "support" information. Instead
+of repurposing the support document, the policies could also be made available
+via a dedicated endpoint.
+
+Instead of querying the server, the client could store the policies in the
+user's account data. If [encrypted] this would prevent the server from tampering
+with the policies the user has consented to. This would, however, not allow
+external users to retrieve the policies.
+
+## Security considerations
+
+The server could fake the terms and respond with a version that is different
+from the one the user consented to.
+
+## Unstable prefix
+
+While this proposal is unstable `policies` should be referred to as
+`org.matrix.msc4266.policies`.
+
+  [account registration]: https://spec.matrix.org/v1.13/client-server-api/#terms-of-service-at-registration
+  [`/.well-known/matrix/support`]: https://spec.matrix.org/v1.13/client-server-api/#getwell-knownmatrixsupport
+  [encrypted]: https://spec.matrix.org/v1.13/client-server-api/#secret-storage