+            index = self._call_api('index', video_id, 'CMS Signing')
+            self._CMS_SIGNING = index.get('cms_signing') or {}
+            if not self._CMS_SIGNING:
+                for signing_policy in index.get('signing_policies', []):
+                    signing_path = signing_policy.get('path')
+                    if signing_path and signing_path.startswith('/cms/'):
+                        name, value = signing_policy.get('name'), signing_policy.get('value')
+                        if name and value:
+                            self._CMS_SIGNING[name] = value