providers/oauth2: fix issues with es256 and add tests (#3808)

fix issues with es256 and add tests

Signed-off-by: Jens Langhammer <jens.langhammer@beryju.org>

Signed-off-by: Jens Langhammer <jens.langhammer@beryju.org>

authentik/core/tests/utils.py

@@ -44,9 +44,11 @@ def create_test_tenant() -> Tenant:
     return Tenant.objects.create(domain=uid, default=True)
 
 
-def create_test_cert() -> CertificateKeyPair:
+def create_test_cert(use_ec_private_key=False) -> CertificateKeyPair:
     """Generate a certificate for testing"""
-    builder = CertificateBuilder()
+    builder = CertificateBuilder(
+        use_ec_private_key=use_ec_private_key,
+    )
     builder.common_name = "goauthentik.io"
     builder.build(
         subject_alt_names=["goauthentik.io"],

authentik/crypto/builder.py

@@ -6,7 +6,8 @@ from typing import Optional
 from cryptography import x509
 from cryptography.hazmat.backends import default_backend
 from cryptography.hazmat.primitives import hashes, serialization
-from cryptography.hazmat.primitives.asymmetric import rsa
+from cryptography.hazmat.primitives.asymmetric import ec, rsa
+from cryptography.hazmat.primitives.asymmetric.types import PRIVATE_KEY_TYPES
 from cryptography.x509.oid import NameOID
 
 from authentik import __version__
@@ -18,7 +19,10 @@ class CertificateBuilder:
 
     common_name: str
 
-    def __init__(self):
+    _use_ec_private_key: bool
+
+    def __init__(self, use_ec_private_key=False):
+        self._use_ec_private_key = use_ec_private_key
         self.__public_key = None
         self.__private_key = None
         self.__builder = None
@@ -36,6 +40,14 @@ class CertificateBuilder:
         self.cert.save()
         return self.cert
 
+    def generate_private_key(self) -> PRIVATE_KEY_TYPES:
+        """Generate private key"""
+        if self._use_ec_private_key:
+            return ec.generate_private_key(curve=ec.SECP256R1)
+        return rsa.generate_private_key(
+            public_exponent=65537, key_size=4096, backend=default_backend()
+        )
+
     def build(
         self,
         validity_days: int = 365,
@@ -43,9 +55,7 @@ class CertificateBuilder:
     ):
         """Build self-signed certificate"""
         one_day = datetime.timedelta(1, 0, 0)
-        self.__private_key = rsa.generate_private_key(
-            public_exponent=65537, key_size=4096, backend=default_backend()
-        )
+        self.__private_key = self.generate_private_key()
         self.__public_key = self.__private_key.public_key()
         alt_names: list[x509.GeneralName] = [x509.DNSName(x) for x in subject_alt_names or []]
         self.__builder = (

authentik/providers/oauth2/tests/test_jwks.py

@@ -3,6 +3,7 @@ import json
 
 from django.test import RequestFactory
 from django.urls.base import reverse
+from jwt import PyJWKSet
 
 from authentik.core.models import Application
 from authentik.core.tests.utils import create_test_cert, create_test_flow
@@ -32,6 +33,7 @@ class TestJWKS(OAuthTestCase):
         )
         body = json.loads(response.content.decode())
         self.assertEqual(len(body["keys"]), 1)
+        PyJWKSet.from_dict(body)
 
     def test_hs256(self):
         """Test JWKS request with HS256"""
@@ -46,3 +48,20 @@ class TestJWKS(OAuthTestCase):
             reverse("authentik_providers_oauth2:jwks", kwargs={"application_slug": app.slug})
         )
         self.assertJSONEqual(response.content.decode(), {})
+
+    def test_es256(self):
+        """Test JWKS request with ES256"""
+        provider = OAuth2Provider.objects.create(
+            name="test",
+            client_id="test",
+            authorization_flow=create_test_flow(),
+            redirect_uris="http://local.invalid",
+            signing_key=create_test_cert(use_ec_private_key=True),
+        )
+        app = Application.objects.create(name="test", slug="test", provider=provider)
+        response = self.client.get(
+            reverse("authentik_providers_oauth2:jwks", kwargs={"application_slug": app.slug})
+        )
+        body = json.loads(response.content.decode())
+        self.assertEqual(len(body["keys"]), 1)
+        PyJWKSet.from_dict(body)

authentik/providers/oauth2/views/jwks.py

@@ -4,6 +4,9 @@ from typing import Optional
 
 from cryptography.hazmat.primitives import hashes
 from cryptography.hazmat.primitives.asymmetric.ec import (
+    SECP256R1,
+    SECP384R1,
+    SECP521R1,
     EllipticCurvePrivateKey,
     EllipticCurvePublicKey,
 )
@@ -26,6 +29,15 @@ def b64_enc(number: int) -> str:
     return final.decode("ascii")
 
 
+# See https://notes.salrahman.com/generate-es256-es384-es512-private-keys/
+# and _CURVE_TYPES in the same file as the below curve files
+ec_crv_map = {
+    SECP256R1: "P-256",
+    SECP384R1: "P-384",
+    SECP521R1: "P-512",
+}
+
+
 class JWKSView(View):
     """Show RSA Key data for Provider"""
 
@@ -54,8 +66,9 @@ class JWKSView(View):
                 "alg": JWTAlgorithms.ES256,
                 "use": "sig",
                 "kid": key.kid,
-                "n": b64_enc(public_numbers.n),
-                "e": b64_enc(public_numbers.e),
+                "x": b64_enc(public_numbers.x),
+                "y": b64_enc(public_numbers.y),
+                "crv": ec_crv_map.get(type(public_key.curve), public_key.curve.name),
             }
         else:
             return key_data