From 268f4bc5d46e05393fecbd2854074b11ab20cd65 Mon Sep 17 00:00:00 2001 From: Simo Sorce Date: Mon, 31 Aug 2026 16:12:54 -0400 Subject: [PATCH] Use checked headers to find kid in JWKSet When verifying a JWS against a JWKSet, check for the 'kid' parameter in chk_hdrs instead of self.jose_header. This ensures that key lookup works properly for signatures that define 'kid' in unprotected headers or when processing multiple signatures. Assisted-by: Gemini:Gemini 3.7 Flash Signed-off-by: Simo Sorce --- jwcrypto/jws.py | 6 +++--- jwcrypto/tests.py | 36 ++++++++++++++++++++++++++++++++++++ 2 files changed, 39 insertions(+), 3 deletions(-) Index: jwcrypto-1.5.7/jwcrypto/jws.py =================================================================== --- jwcrypto-1.5.7.orig/jwcrypto/jws.py +++ jwcrypto-1.5.7/jwcrypto/jws.py @@ -297,11 +297,11 @@ class JWS: self.verifylog.append("Success") elif isinstance(key, JWKSet): keys = key - if 'kid' in self.jose_header: - kid_keys = key.get_keys(self.jose_header['kid']) + if 'kid' in chk_hdrs: + kid_keys = key.get_keys(chk_hdrs['kid']) if not kid_keys: raise JWKeyNotFound('Key ID {} not in key set'.format( - self.jose_header['kid'])) + chk_hdrs['kid'])) keys = kid_keys for k in keys: Index: jwcrypto-1.5.7/jwcrypto/tests.py =================================================================== --- jwcrypto-1.5.7.orig/jwcrypto/tests.py +++ jwcrypto-1.5.7/jwcrypto/tests.py @@ -1194,6 +1194,42 @@ class TestJWS(unittest.TestCase): with self.assertRaises(JWKeyNotFound): s4.deserialize(s3.serialize(), ks) + def test_multiple_signatures_keyset(self): + ks = jwk.JWKSet() + key1 = jwk.JWK.generate(kty='oct', alg='HS256', kid='key1') + key2 = jwk.JWK.generate(kty='oct', alg='HS256', kid='key2') + ks.add(key1) + ks.add(key2) + + payload = b'JSON Serialization JWS with multiple signatures' + s = jws.JWS(payload=payload) + s.add_signature(key1, protected={'alg': 'HS256', 'kid': 'key1'}) + s.add_signature(key2, protected={'alg': 'HS256'}, + header={'kid': 'key2'}) + + serialized = s.serialize() + decoded = json_decode(serialized) + self.assertIn('signatures', decoded) + self.assertEqual(len(decoded['signatures']), 2) + + s2 = jws.JWS() + s2.deserialize(serialized, ks) + self.assertTrue(s2.is_valid) + self.assertEqual(s2.payload, payload) + + # Test with keys swapped + key1_dict = key1.export(as_dict=True) + key1_dict['kid'] = 'key2' + key2_dict = key2.export(as_dict=True) + key2_dict['kid'] = 'key1' + ks_swapped = jwk.JWKSet() + ks_swapped.add(jwk.JWK(**key1_dict)) + ks_swapped.add(jwk.JWK(**key2_dict)) + + s3 = jws.JWS() + with self.assertRaises(JWKeyNotFound): + s3.deserialize(serialized, ks_swapped) + E_A1_plaintext = \ [84, 104, 101, 32, 116, 114, 117, 101, 32, 115, 105, 103, 110, 32,