{
    "rules": {
        ".read" : "auth != null",
        ".write": "auth != null",

        "messages": {
            "$msg_id": {
                ".validate": "auth.is_operator == true || newData.child('conversation_id').val() == root.child('chat_users').child(auth.uid).child('conversation_id').val()"
            }
        }
    }
}