feat: allow for forcing asymmetric jwts (openedx#32045)

Add a temporary feature toggle to force the LMS to
only produce asymmetric JWTs. This is a part of
DEPR of Symmetric JWTs:
openedx/public-engineering#83

openedx/core/djangoapps/oauth_dispatch/jwt.py

@@ -6,8 +6,9 @@
 from time import time
 
 from django.conf import settings
-from edx_django_utils.monitoring import set_custom_attribute
+from edx_django_utils.monitoring import increment, set_custom_attribute
 from edx_rbac.utils import create_role_auth_claim_for_user
+from edx_toggles.toggles import SettingToggle
 from jwkest import jwk
 from jwkest.jws import JWS
 
@@ -159,6 +160,12 @@ def _create_jwt(
         secret (string): Overrides configured JWT secret (signing) key.
     """
     use_asymmetric_key = _get_use_asymmetric_key_value(is_restricted, use_asymmetric_key)
+    # Enable monitoring of key type used. Use increment in case there are multiple calls in a transaction.
+    if use_asymmetric_key:
+        increment('create_asymmetric_jwt_count')
+    else:
+        increment('create_symmetric_jwt_count')
+
     # Default scopes should only contain non-privileged data.
     # Do not be misled by the fact that `email` and `profile` are default scopes. They
     # were included for legacy compatibility, even though they contain privileged data.
@@ -188,10 +195,27 @@ def _create_jwt(
     return _encode_and_sign(payload, use_asymmetric_key, secret)
 
 
+# .. toggle_name: JWT_AUTH_FORCE_CREATE_ASYMMETRIC
+# .. toggle_implementation: SettingToggle
+# .. toggle_default: False
+# .. toggle_description: When True, forces the LMS to only create JWTs signed with the asymmetric
+#   key. This is a temporary rollout toggle for DEPR of symmetric JWTs.
+# .. toggle_use_cases: temporary
+# .. toggle_creation_date: 2023-04-10
+# .. toggle_target_removal_date: 2023-07-31
+# .. toggle_tickets: https://github.com/openedx/public-engineering/issues/83
+JWT_AUTH_FORCE_CREATE_ASYMMETRIC = SettingToggle(
+    'JWT_AUTH_FORCE_CREATE_ASYMMETRIC', default=False, module_name=__name__
+)
+
+
 def _get_use_asymmetric_key_value(is_restricted, use_asymmetric_key):
     """
     Returns the value to use for use_asymmetric_key.
     """
+    if JWT_AUTH_FORCE_CREATE_ASYMMETRIC.is_enabled():
+        return True
+
     return use_asymmetric_key or is_restricted
 
 

openedx/core/djangoapps/oauth_dispatch/tests/test_jwt.py

@@ -73,6 +73,11 @@ def test_dot_create_jwt_for_token_with_asymmetric(self):
         jwt_token = self._create_jwt_for_token(DOTAdapter(), use_asymmetric_key=True)
         self._assert_jwt_is_valid(jwt_token, should_be_asymmetric_key=True)
 
+    @override_settings(JWT_AUTH_FORCE_CREATE_ASYMMETRIC=True)
+    def test_dot_create_jwt_for_token_forced_asymmetric(self):
+        jwt_token = self._create_jwt_for_token(DOTAdapter(), use_asymmetric_key=False)
+        self._assert_jwt_is_valid(jwt_token, should_be_asymmetric_key=True)
+
     def test_create_jwt_for_token_default_expire_seconds(self):
         oauth_adapter = DOTAdapter()
         jwt_token = self._create_jwt_for_token(oauth_adapter, use_asymmetric_key=False)