1 files changed, 35 insertions, 0 deletions
diff --git a/gn3/oauth2/jwks.py b/gn3/oauth2/jwks.py
new file mode 100644
index 0000000..adaa3e9
--- /dev/null
+++ b/gn3/oauth2/jwks.py
@@ -0,0 +1,35 @@
+"""Utilities dealing with JSON Web Keys (JWK)"""
+from urllib.parse import urljoin
+
+import requests
+from flask import current_app as app
+from authlib.jose.errors import BadSignatureError
+from authlib.jose import KeySet, JsonWebKey, JsonWebToken
+
+from gn3.oauth2.errors import TokenValidationError
+
+
+def fetch_jwks(authserveruri: str, path: str = "auth/public-jwks") -> KeySet:
+    """Fetch the JWKs from a particular URI"""
+    try:
+        response = requests.get(urljoin(authserveruri, path))
+        if response.status_code == 200:
+            return KeySet([
+                JsonWebKey.import_key(key) for key in response.json()["jwks"]])
+    except Exception as _exc:
+        app.logger.debug("There was an error fetching the JSON Web Keys.",
+                         exc_info=True)
+
+    return KeySet([])
+
+
+def validate_token(token: str, keys: KeySet) -> dict:
+    """Validate the token against the given keys."""
+    for key in keys.keys:
+        kd = key.as_dict()
+        try:
+            return JsonWebToken(["RS256"]).decode(token, key=key)
+        except BadSignatureError as _bse:
+            pass
+
+    raise TokenValidationError("No key was found for validation.")