Multiple rsa keys (#978)

* Support rotation of RSA keys

* add author

* changelog for #950

Co-authored-by: Asif Saif Uddin <[email protected]>

Author: dylantack

AUTHORS

@@ -26,6 +26,7 @@ David Smith
 Diego Garcia
 Dulmandakh Sukhbaatar
 Dylan Giesler
+Dylan Tack
 Emanuele Palazzetti
 Federico Dolce
 Frederico Vieira

CHANGELOG.md

@@ -22,6 +22,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 ### Added
 * #712, #636, #808. Calls to `django.contrib.auth.authenticate()` now pass a `request`
   to provide compatibility with backends that need one.
+* #950 Add support for RSA key rotation.
 
 ### Fixed
 * #524 Restrict usage of timezone aware expire dates to Django projects with USE_TZ set to True.

docs/oidc.rst

@@ -100,6 +100,30 @@ change this class to derive from ``oauthlib.openid.Server`` instead of
 With ``RSA`` key-pairs, the public key can be generated from the private key,
 so there is no need to add a setting for the public key.
 
+
+Rotating the RSA private key
+~~~~~~~~~~~~~~~~~~~~~~~~
+Extra keys can be published in the jwks_uri with the ``OIDC_RSA_PRIVATE_KEYS_INACTIVE``
+setting. For example:::
+
+    OAUTH2_PROVIDER = {
+        "OIDC_RSA_PRIVATE_KEY": os.environ.get("OIDC_RSA_PRIVATE_KEY"),
+        "OIDC_RSA_PRIVATE_KEYS_INACTIVE": [
+            os.environ.get("OIDC_RSA_PRIVATE_KEY_2"),
+            os.environ.get("OIDC_RSA_PRIVATE_KEY_3")
+        ]
+        # ... other settings
+    }
+
+To rotate, follow these steps:
+
+#. Generate a new key, and add it to the inactive set. Then deploy the app.
+#. Swap the active and inactive keys, then re-deploy.
+#. After some reasonable amount of time, remove the inactive key. At a minimum,
+   you should wait ``ID_TOKEN_EXPIRE_SECONDS`` to ensure the key isn't removed
+   before valid tokens expire.
+
+
 Using ``HS256`` keys
 ~~~~~~~~~~~~~~~~~~~~
 
@@ -297,7 +321,7 @@ query, and other details.
 JwksInfoView
 ~~~~~~~~~~~~
 
-Available at ``/o/.well-known/jwks.json``, this view provides details of the key used to sign
+Available at ``/o/.well-known/jwks.json``, this view provides details of the keys used to sign
 the JWTs generated for ID tokens, so that clients are able to verify them.
 
 

docs/settings.rst

@@ -264,6 +264,25 @@ Default: ``""``
 
 The RSA private key used to sign OIDC ID tokens. If not set, OIDC is disabled.
 
+OIDC_RSA_PRIVATE_KEYS_INACTIVE
+~~~~~~~~~~~~~~~~~~~~
+Default: ``[]``
+
+An array of *inactive* RSA private keys. These keys are not used to sign tokens,
+but are published in the jwks_uri location.
+
+This is useful for providing a smooth transition during key rotation.
+``OIDC_RSA_PRIVATE_KEY`` can be replaced, and recently decommissioned keys
+should be retained in this inactive list.
+
+OIDC_JWKS_MAX_AGE_SECONDS
+~~~~~~~~~~~~~~~~~~~~~~
+Default: ``3600``
+
+The max-age value for the Cache-Control header on jwks_uri.
+
+This enables the verifier to safely cache the JWK Set and not have to re-download
+the document for every token.
 
 OIDC_USERINFO_ENDPOINT
 ~~~~~~~~~~~~~~~~~~~~~~

oauth2_provider/settings.py

@@ -72,6 +72,8 @@
     "OIDC_ISS_ENDPOINT": "",
     "OIDC_USERINFO_ENDPOINT": "",
     "OIDC_RSA_PRIVATE_KEY": "",
+    "OIDC_RSA_PRIVATE_KEYS_INACTIVE": [],
+    "OIDC_JWKS_MAX_AGE_SECONDS": 3600,
     "OIDC_RESPONSE_TYPES_SUPPORTED": [
         "code",
         "token",

oauth2_provider/views/oidc.py

@@ -71,12 +71,23 @@ class JwksInfoView(OIDCOnlyMixin, View):
     def get(self, request, *args, **kwargs):
         keys = []
         if oauth2_settings.OIDC_RSA_PRIVATE_KEY:
-            key = jwk.JWK.from_pem(oauth2_settings.OIDC_RSA_PRIVATE_KEY.encode("utf8"))
-            data = {"alg": "RS256", "use": "sig", "kid": key.thumbprint()}
-            data.update(json.loads(key.export_public()))
-            keys.append(data)
+            for pem in [
+                oauth2_settings.OIDC_RSA_PRIVATE_KEY,
+                *oauth2_settings.OIDC_RSA_PRIVATE_KEYS_INACTIVE,
+            ]:
+
+                key = jwk.JWK.from_pem(pem.encode("utf8"))
+                data = {"alg": "RS256", "use": "sig", "kid": key.thumbprint()}
+                data.update(json.loads(key.export_public()))
+                keys.append(data)
         response = JsonResponse({"keys": keys})
         response["Access-Control-Allow-Origin"] = "*"
+        response["Cache-Control"] = (
+            "Cache-Control: public, "
+            + f"max-age={oauth2_settings.OIDC_JWKS_MAX_AGE_SECONDS}, "
+            + f"stale-while-revalidate={oauth2_settings.OIDC_JWKS_MAX_AGE_SECONDS}, "
+            + f"stale-if-error={oauth2_settings.OIDC_JWKS_MAX_AGE_SECONDS}"
+        )
         return response
 
 

tests/presets.py

@@ -12,6 +12,7 @@
     "OIDC_ISS_ENDPOINT": "http://localhost/o",
     "OIDC_USERINFO_ENDPOINT": "http://localhost/o/userinfo/",
     "OIDC_RSA_PRIVATE_KEY": settings.OIDC_RSA_PRIVATE_KEY,
+    "OIDC_RSA_PRIVATE_KEYS_INACTIVE": settings.OIDC_RSA_PRIVATE_KEYS_INACTIVE,
     "SCOPES": {
         "read": "Reading scope",
         "write": "Writing scope",

tests/settings.py

@@ -134,6 +134,24 @@
 dTnvCVtA59ne4LEVie/PMH/odQWY0SxVm/76uBZv/1vY
 -----END RSA PRIVATE KEY-----"""
 
+OIDC_RSA_PRIVATE_KEYS_INACTIVE = [
+    """-----BEGIN RSA PRIVATE KEY-----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+-----END RSA PRIVATE KEY-----"""
+]
+
 OAUTH2_PROVIDER_ACCESS_TOKEN_MODEL = "oauth2_provider.AccessToken"
 OAUTH2_PROVIDER_APPLICATION_MODEL = "oauth2_provider.Application"
 OAUTH2_PROVIDER_REFRESH_TOKEN_MODEL = "oauth2_provider.RefreshToken"

tests/test_oidc_views.py

@@ -71,6 +71,7 @@ def test_get_connect_discovery_info_without_rsa_key(self):
 @pytest.mark.oauth2_settings(presets.OIDC_SETTINGS_RW)
 class TestJwksInfoView(TestCase):
     def test_get_jwks_info(self):
+        self.oauth2_settings.OIDC_RSA_PRIVATE_KEYS_INACTIVE = []
         expected_response = {
             "keys": [
                 {
@@ -93,6 +94,31 @@ def test_get_jwks_info_no_rsa_key(self):
         self.assertEqual(response.status_code, 200)
         assert response.json() == {"keys": []}
 
+    def test_get_jwks_info_multiple_rsa_keys(self):
+        expected_response = {
+            "keys": [
+                {
+                    "alg": "RS256",
+                    "e": "AQAB",
+                    "kid": "s4a1o8mFEd1tATAIH96caMlu4hOxzBUaI2QTqbYNBHs",
+                    "kty": "RSA",
+                    "n": "mwmIeYdjZkLgalTuhvvwjvnB5vVQc7G9DHgOm20Hw524bLVTk49IXJ2Scw42HOmowWWX-oMVT_ca3ZvVIeffVSN1-TxVy2zB65s0wDMwhiMoPv35z9IKHGMZgl9vlyso_2b7daVF_FQDdgIayUn8TQylBxEU1RFfW0QSYOBdAt8",  # noqa
+                    "use": "sig",
+                },
+                {
+                    "alg": "RS256",
+                    "e": "AQAB",
+                    "kid": "AJ_IkYJUFWqiKKE2FvPIESroTvownbaj0OzL939oIIE",
+                    "kty": "RSA",
+                    "n": "0qVzbcWg_fgygZ0liTaFeodD2bkinhj8gPJ9P2rPzvqG6ImI9YKkEk8Dxcc7eWcudnw5iEL8wx_tgooaRiHiYfUrFBBXfA15D_15PdX_5gG8rQbJ7XMxQrYoRUcVm2wQDB4fIuR7sTPqx9p8OR4f--BixOfM5Oa7SEUtQ8kvrlE",  # noqa
+                    "use": "sig",
+                },
+            ]
+        }
+        response = self.client.get(reverse("oauth2_provider:jwks-info"))
+        self.assertEqual(response.status_code, 200)
+        assert response.json() == expected_response
+
 
 @pytest.mark.django_db
 @pytest.mark.parametrize("method", ["get", "post"])