Explicit check the key for ECAlgorithm (#713)

* Explicit check the key for ECAlgorithm

* [pre-commit.ci] auto fixes from pre-commit.com hooks

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Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>

1 files changed, 6 insertions, 0 deletions

diff --git a/jwt/algorithms.py b/jwt/algorithms.py
index 1f8865a..739df80 100644
--- a/jwt/algorithms.py
+++ b/jwt/algorithms.py
@@ -417,6 +417,12 @@ if has_crypto:
             except ValueError:
                 key = load_pem_private_key(key, password=None)
 
+            # Explicit check the key to prevent confusing errors from cryptography
+            if not isinstance(key, (EllipticCurvePrivateKey, EllipticCurvePublicKey)):
+                raise InvalidKeyError(
+                    "Expecting a EllipticCurvePrivateKey/EllipticCurvePublicKey. Wrong key provided for ECDSA algorithms"
+                )
+
             return key
 
         def sign(self, msg, key):