ensure digest input is bytes

lemur/auth/service.py

@@ -100,7 +100,10 @@ def decode_with_multiple_secrets(encoded_jwt, secrets, algorithms):
             continue
         if len(secrets) > 1:
             digest = hashes.Hash(hashes.SHA256(), backend=default_backend())
-            digest.update(secret)
+            if isinstance(secret, str):
+                digest.update(secret.encode())
+            else:
+                digest.update(secret)
             metrics.send("jwt_decode", "counter", 1, metric_tags={**dict(kid=index, fingerprint=digest.finalize().hex()), **payload})
         return payload
     if errors:

lemur/tests/test_auth.py

@@ -0,0 +1,30 @@
+from unittest.mock import patch
+
+from cryptography.hazmat.primitives import hashes
+from cryptography.hazmat.backends import default_backend
+import jwt
+from lemur.auth.service import decode_with_multiple_secrets
+
+
+@patch("lemur.auth.service.metrics")
+def test_decode_with_multiple_secrets(mock_metrics):
+    # Given
+    secret = "my_secret"
+    encoded_jwt = jwt.encode({"foo": "bar"}, secret, algorithm='HS256')
+    secrets = [secret, secret + "2"]
+    algorithms = ['HS256']
+
+    # When
+    payload = decode_with_multiple_secrets(encoded_jwt, secrets, algorithms)
+
+    # Then
+    assert payload == {"foo": "bar"}
+    digest = hashes.Hash(hashes.SHA256(), backend=default_backend())
+    digest.update(secret.encode())
+    mock_metrics.send.assert_called_once_with(
+        "jwt_decode", "counter", 1,
+        metric_tags={
+            **dict(kid=0, fingerprint=digest.finalize().hex()),
+            **{"foo": "bar"}
+        }
+    )