diff --git a/synapse/api/constants.py b/synapse/api/constants.py
index 5baba43966bb..92b5790557a2 100644
--- a/synapse/api/constants.py
+++ b/synapse/api/constants.py
@@ -1,6 +1,7 @@
 # -*- coding: utf-8 -*-
 # Copyright 2014-2016 OpenMarket Ltd
 # Copyright 2017 Vector Creations Ltd
+# Copyright 2018 New Vector Ltd
 #
 # Licensed under the Apache License, Version 2.0 (the "License");
 # you may not use this file except in compliance with the License.
@@ -70,6 +71,7 @@ class EventTypes(object):
     CanonicalAlias = "m.room.canonical_alias"
     RoomAvatar = "m.room.avatar"
     GuestAccess = "m.room.guest_access"
+    Encryption = "m.room.encryption"
 
     # These are used for validation
     Message = "m.room.message"
diff --git a/synapse/handlers/room.py b/synapse/handlers/room.py
index 8df8fcbbadc6..bcb54fe41ad4 100644
--- a/synapse/handlers/room.py
+++ b/synapse/handlers/room.py
@@ -46,12 +46,14 @@ class RoomCreationHandler(BaseHandler):
             "history_visibility": "shared",
             "original_invitees_have_ops": False,
             "guest_can_join": True,
+            "encryption_alg": "m.megolm.v1.aes-sha2",
         },
         RoomCreationPreset.TRUSTED_PRIVATE_CHAT: {
             "join_rules": JoinRules.INVITE,
             "history_visibility": "shared",
             "original_invitees_have_ops": True,
             "guest_can_join": True,
+            "encryption_alg": "m.megolm.v1.aes-sha2",
         },
         RoomCreationPreset.PUBLIC_CHAT: {
             "join_rules": JoinRules.PUBLIC,
@@ -373,6 +375,15 @@ def send(etype, content, **kwargs):
                 content=content,
             )
 
+        if "encryption_alg" in config:
+            send(
+                etype=EventTypes.Encryption,
+                state_key="",
+                content={
+                    'algorithm': config["encryption_alg"],
+                }
+            )
+
 
 class RoomContextHandler(BaseHandler):
     @defer.inlineCallbacks