feat: support import key from a certificate pem file

src/joserfc/rfc7517/pem.py

@@ -1,6 +1,7 @@
 from __future__ import annotations
 from typing import Any, Literal, cast
 from abc import ABCMeta, abstractmethod
+from cryptography.x509 import load_pem_x509_certificate
 from cryptography.hazmat.primitives.serialization import (
     load_pem_private_key,
     load_pem_public_key,
@@ -38,6 +39,10 @@ def load_pem_key(
     elif b"PRIVATE" in raw:
         key = load_pem_private_key(raw, password=password, backend=default_backend())
 
+    elif b"CERTIFICATE" in raw:
+        cert = load_pem_x509_certificate(raw, backend=default_backend())
+        return cert.public_key()
+
     else:
         try:
             key = load_der_private_key(raw, password=password, backend=default_backend())

tests/jwk/test_rsa_key.py

@@ -133,6 +133,12 @@ def test_import_from_der_bytes(self):
         key1 = RSAKey.import_key(value1)
         self.assertEqual(value1, key1.as_der())
 
+    def test_import_from_certificate(self):
+        firebase_cert = read_key("firebase-cert.pem")
+        key: RSAKey = RSAKey.import_key(firebase_cert)
+        data = key.as_dict()
+        self.assertEqual(data['kty'], 'RSA')
+
     def test_output_with_password(self):
         private_pem = read_key("rsa-openssl-private.pem")
         key: RSAKey = RSAKey.import_key(private_pem)

tests/keys/firebase-cert.pem

@@ -0,0 +1,19 @@
+-----BEGIN CERTIFICATE-----
+MIIDHTCCAgWgAwIBAgIJANuivDoSiT/NMA0GCSqGSIb3DQEBBQUAMDExLzAtBgNV
+BAMMJnNlY3VyZXRva2VuLnN5c3RlbS5nc2VydmljZWFjY291bnQuY29tMB4XDTI0
+MTIxMDA3MzI0OVoXDTI0MTIyNjE5NDc0OVowMTEvMC0GA1UEAwwmc2VjdXJldG9r
+ZW4uc3lzdGVtLmdzZXJ2aWNlYWNjb3VudC5jb20wggEiMA0GCSqGSIb3DQEBAQUA
+A4IBDwAwggEKAoIBAQDhywhKx2L+GZJLjmGcOVMCc+x09hrYpCVk3K/LxgJtZZ34
+vHeFUjGexazZiSc9LHd03fNmATFcdtqpVW4Qz+xsP5mQXEqbwPQu2qWZhb5VY8Z6
+Oh02uFFxRCdegupuzggdqEhc/QlkrKb2Y/undxcIyRcXKWcDaEn+5dqQA2NhjMp5
+ir1YsKRanZIJ69wR65Ok8e0YlHHGsP+7uJaW0b1yr0RyilyluEsb7DmpMV/7j7pr
+cnNnOnL7jhpLW2gjbVzjB1FR5ScNy5gKp72htFkxdGxS58/AQoT06kBu80OI2VMb
+mijU6JD4b3tIYtHZp9FOiCNhiQS1e/GTDyGT1ZT1AgMBAAGjODA2MAwGA1UdEwEB
+/wQCMAAwDgYDVR0PAQH/BAQDAgeAMBYGA1UdJQEB/wQMMAoGCCsGAQUFBwMCMA0G
+CSqGSIb3DQEBBQUAA4IBAQDOf4MfPzEesqqm50J0gVW1geCiukD6MrH1nPGuUhm8
+FUYy/4W6Rx69XnKKRxb1rEQwrqmi8WNiELRrpXugY5ieowuRwlcrPk450bB1IwK5
+Jxcqgf4fxwbvqeoADzl0Z0+JxoiYDpH2FMG1HRpdl/YCzB7W0ftv3q1uUqTDLQ+r
+K6Cm1rHyznsOio9oJknkQ8mPbvE7qSRdCYir806gGurzyhO1RacbR97B8M/vujyc
+sNxCxxSphHCgCBW1mz4XqgOF4Sd/XYPrO8/2qhoSjqaqta+gmg644afx82NqsW+Z
+NJrR9cZxaLNEfwzv+fX9s70xT1nSa9U4avINE58o3Dsk
+-----END CERTIFICATE-----