diff --git a/api_signaling.go b/api_signaling.go
index 8f7e959..e1d0514 100644
--- a/api_signaling.go
+++ b/api_signaling.go
@@ -620,6 +620,18 @@ type RoomFlagsServerMessage struct {
 	Flags     uint32 `json:"flags"`
 }
 
+type ChatComment map[string]interface{}
+
+type RoomEventMessageDataChat struct {
+	Comment *ChatComment `json:"comment,omitempty"`
+}
+
+type RoomEventMessageData struct {
+	Type string `json:"type"`
+
+	Chat *RoomEventMessageDataChat `json:"chat,omitempty"`
+}
+
 type EventServerMessage struct {
 	Target string `json:"target"`
 	Type   string `json:"type"`
@@ -646,6 +658,15 @@ type EventServerMessageSessionEntry struct {
 	RoomSessionId string           `json:"roomsessionid,omitempty"`
 }
 
+func (e *EventServerMessageSessionEntry) Clone() *EventServerMessageSessionEntry {
+	return &EventServerMessageSessionEntry{
+		SessionId:     e.SessionId,
+		UserId:        e.UserId,
+		User:          e.User,
+		RoomSessionId: e.RoomSessionId,
+	}
+}
+
 // MCU-related types
 
 type AnswerOfferMessage struct {
diff --git a/clientsession.go b/clientsession.go
index a68d707..f85437e 100644
--- a/clientsession.go
+++ b/clientsession.go
@@ -214,6 +214,9 @@ func (s *ClientSession) hasAnyPermissionLocked(permission ...Permission) bool {
 func (s *ClientSession) hasPermissionLocked(permission Permission) bool {
 	if !s.supportsPermissions {
 		// Old-style session that doesn't receive permissions from Nextcloud.
+		if result, found := DefaultPermissionOverrides[permission]; found {
+			return result
+		}
 		return true
 	}
 
@@ -641,6 +644,11 @@ func (s *ClientSession) SendError(e *Error) bool {
 }
 
 func (s *ClientSession) SendMessage(message *ServerMessage) bool {
+	message = s.filterMessage(message)
+	if message == nil {
+		return true
+	}
+
 	s.mu.Lock()
 	defer s.mu.Unlock()
 
@@ -1026,6 +1034,110 @@ func (s *ClientSession) storePendingMessage(message *ServerMessage) {
 	}
 }
 
+func filterDisplayNames(events []*EventServerMessageSessionEntry) []*EventServerMessageSessionEntry {
+	result := make([]*EventServerMessageSessionEntry, 0, len(events))
+	for _, event := range events {
+		if event.User == nil {
+			result = append(result, event)
+			continue
+		}
+
+		var userdata map[string]interface{}
+		if err := json.Unmarshal(*event.User, &userdata); err != nil {
+			result = append(result, event)
+			continue
+		}
+
+		if _, found := userdata["displayname"]; !found {
+			result = append(result, event)
+			continue
+		}
+
+		delete(userdata, "displayname")
+		if len(userdata) == 0 {
+			// No more userdata, no need to serialize empty map.
+			e := event.Clone()
+			e.User = nil
+			result = append(result, e)
+			continue
+		}
+
+		data, err := json.Marshal(userdata)
+		if err != nil {
+			result = append(result, event)
+			continue
+		}
+
+		e := event.Clone()
+		e.User = (*json.RawMessage)(&data)
+		result = append(result, e)
+	}
+	return result
+}
+
+func (s *ClientSession) filterMessage(message *ServerMessage) *ServerMessage {
+	switch message.Type {
+	case "event":
+		switch message.Event.Target {
+		case "participants":
+			if message.Event.Type == "update" {
+				m := message.Event.Update
+				users := make(map[string]bool)
+				for _, entry := range m.Users {
+					users[entry["sessionId"].(string)] = true
+				}
+				for _, entry := range m.Changed {
+					if users[entry["sessionId"].(string)] {
+						continue
+					}
+					m.Users = append(m.Users, entry)
+				}
+				// TODO(jojo): Only send all users if current session id has
+				// changed its "inCall" flag to true.
+				m.Changed = nil
+			}
+		case "room":
+			switch message.Event.Type {
+			case "join":
+				if s.HasPermission(PERMISSION_HIDE_DISPLAYNAMES) {
+					message.Event.Join = filterDisplayNames(message.Event.Join)
+				}
+			case "message":
+				if message.Event.Message == nil || message.Event.Message.Data == nil || len(*message.Event.Message.Data) == 0 || !s.HasPermission(PERMISSION_HIDE_DISPLAYNAMES) {
+					return message
+				}
+
+				var data RoomEventMessageData
+				if err := json.Unmarshal(*message.Event.Message.Data, &data); err != nil {
+					return message
+				}
+
+				if data.Type == "chat" && data.Chat != nil && data.Chat.Comment != nil {
+					if displayName, found := (*data.Chat.Comment)["actorDisplayName"]; found && displayName != "" {
+						(*data.Chat.Comment)["actorDisplayName"] = ""
+						if encoded, err := json.Marshal(data); err == nil {
+							message.Event.Message.Data = (*json.RawMessage)(&encoded)
+						}
+					}
+				}
+			}
+		}
+	case "message":
+		if message.Message != nil && message.Message.Data != nil && len(*message.Message.Data) > 0 && s.HasPermission(PERMISSION_HIDE_DISPLAYNAMES) {
+			var data MessageServerMessageData
+			if err := json.Unmarshal(*message.Message.Data, &data); err != nil {
+				return message
+			}
+
+			if data.Type == "nickChanged" {
+				return nil
+			}
+		}
+	}
+
+	return message
+}
+
 func (s *ClientSession) processNatsMessage(msg *NatsMessage) *ServerMessage {
 	switch msg.Type {
 	case "message":
@@ -1050,23 +1162,7 @@ func (s *ClientSession) processNatsMessage(msg *NatsMessage) *ServerMessage {
 				return nil
 			}
 		case "event":
-			if msg.Message.Event.Target == "participants" &&
-				msg.Message.Event.Type == "update" {
-				m := msg.Message.Event.Update
-				users := make(map[string]bool)
-				for _, entry := range m.Users {
-					users[entry["sessionId"].(string)] = true
-				}
-				for _, entry := range m.Changed {
-					if users[entry["sessionId"].(string)] {
-						continue
-					}
-					m.Users = append(m.Users, entry)
-				}
-				// TODO(jojo): Only send all users if current session id has
-				// changed its "inCall" flag to true.
-				m.Changed = nil
-			} else if msg.Message.Event.Target == "room" {
+			if msg.Message.Event.Target == "room" {
 				// Can happen mostly during tests where an older room NATS message
 				// could be received by a subscriber that joined after it was sent.
 				if msg.SendTime.Before(s.getRoomJoinTime()) {
diff --git a/hub_test.go b/hub_test.go
index 9305275..a4e2e01 100644
--- a/hub_test.go
+++ b/hub_test.go
@@ -259,6 +259,14 @@ func processAuthRequest(t *testing.T, w http.ResponseWriter, r *http.Request, re
 			UserId:  params.UserId,
 		},
 	}
+	userdata := map[string]string{
+		"displayname": "Displayname " + params.UserId,
+	}
+	if data, err := json.Marshal(userdata); err != nil {
+		t.Fatal(err)
+	} else {
+		response.Auth.User = (*json.RawMessage)(&data)
+	}
 	return response
 }
 
@@ -1827,6 +1835,88 @@ func TestJoinMultiple(t *testing.T) {
 	}
 }
 
+func TestJoinMultipleDisplaynamesPermission(t *testing.T) {
+	hub, _, _, server := CreateHubForTest(t)
+
+	client1 := NewTestClient(t, server, hub)
+	defer client1.CloseWithBye()
+	if err := client1.SendHello(testDefaultUserId + "1"); err != nil {
+		t.Fatal(err)
+	}
+	client2 := NewTestClient(t, server, hub)
+	defer client2.CloseWithBye()
+	if err := client2.SendHello(testDefaultUserId + "2"); err != nil {
+		t.Fatal(err)
+	}
+
+	ctx, cancel := context.WithTimeout(context.Background(), testTimeout)
+	defer cancel()
+
+	hello1, err := client1.RunUntilHello(ctx)
+	if err != nil {
+		t.Fatal(err)
+	}
+	hello2, err := client2.RunUntilHello(ctx)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	session2 := hub.GetSessionByPublicId(hello2.Hello.SessionId).(*ClientSession)
+	if session2 == nil {
+		t.Fatalf("Session %s does not exist", hello2.Hello.SessionId)
+	}
+
+	// Client 2 may not receive display names.
+	session2.SetPermissions([]Permission{PERMISSION_HIDE_DISPLAYNAMES})
+
+	// Join room by id (first client).
+	roomId := "test-room"
+	if room, err := client1.JoinRoom(ctx, roomId); err != nil {
+		t.Fatal(err)
+	} else if room.Room.RoomId != roomId {
+		t.Fatalf("Expected room %s, got %s", roomId, room.Room.RoomId)
+	}
+
+	// We will receive a "joined" event.
+	if err := client1.RunUntilJoined(ctx, hello1.Hello); err != nil {
+		t.Error(err)
+	}
+
+	// Join room by id (second client).
+	if room, err := client2.JoinRoom(ctx, roomId); err != nil {
+		t.Fatal(err)
+	} else if room.Room.RoomId != roomId {
+		t.Fatalf("Expected room %s, got %s", roomId, room.Room.RoomId)
+	}
+
+	// We will receive a "joined" event for the first and the second client.
+	if events, unexpected, err := client2.RunUntilJoinedAndReturn(ctx, hello1.Hello, hello2.Hello); err != nil {
+		t.Error(err)
+	} else {
+		if len(unexpected) > 0 {
+			t.Errorf("Received unexpected messages: %+v", unexpected)
+		} else if len(events) != 2 {
+			t.Errorf("Expected two event, got %+v", events)
+		} else if events[0].User != nil {
+			t.Errorf("Expected empty userdata for first event, got %+v", events[0].User)
+		} else if events[1].User != nil {
+			t.Errorf("Expected empty userdata for second event, got %+v", events[1].User)
+		}
+	}
+	// The first client will also receive a "joined" event from the second client.
+	if events, unexpected, err := client1.RunUntilJoinedAndReturn(ctx, hello2.Hello); err != nil {
+		t.Error(err)
+	} else {
+		if len(unexpected) > 0 {
+			t.Errorf("Received unexpected messages: %+v", unexpected)
+		} else if len(events) != 1 {
+			t.Errorf("Expected one event, got %+v", events)
+		} else if events[0].User == nil {
+			t.Errorf("Expected userdata for first event, got nothing")
+		}
+	}
+}
+
 func TestJoinRoomSwitchClient(t *testing.T) {
 	hub, _, _, server := CreateHubForTest(t)
 
diff --git a/session.go b/session.go
index 9a8da88..de04ca5 100644
--- a/session.go
+++ b/session.go
@@ -36,6 +36,14 @@ var (
 	PERMISSION_MAY_PUBLISH_SCREEN Permission = "publish-screen"
 	PERMISSION_MAY_CONTROL        Permission = "control"
 	PERMISSION_TRANSIENT_DATA     Permission = "transient-data"
+	PERMISSION_HIDE_DISPLAYNAMES  Permission = "hide-displaynames"
+
+	// DefaultPermissionOverrides contains permission overrides for users where
+	// no permissions have been set by the server. If a permission is not set in
+	// this map, it's assumed the user has that permission.
+	DefaultPermissionOverrides = map[Permission]bool{
+		PERMISSION_HIDE_DISPLAYNAMES: false,
+	}
 )
 
 type SessionIdData struct {