Merge uo 3.4.4 to 4.0.x

Author: Spomky

src/Library/KeyManagement/KeyConverter/KeyConverter.php

@@ -162,8 +162,9 @@ public static function loadFromX5C(array $x5c): array
             throw new InvalidArgumentException('The certificate chain is empty');
         }
         foreach ($x5c as $id => $cert) {
+            assert(is_string($cert), 'Invalid certificate chain');
             $x5c[$id] = '-----BEGIN CERTIFICATE-----' . "\n" . chunk_split(
-                (string) $cert,
+                $cert,
                 64,
                 "\n"
             ) . '-----END CERTIFICATE-----';
@@ -180,6 +181,9 @@ public static function loadFromX5C(array $x5c): array
         return self::loadKeyFromCertificate(reset($x5c));
     }
 
+    /**
+     * @return array<array-key, mixed>
+     */
     private static function loadKeyFromDER(string $der, ?string $password = null): array
     {
         $pem = self::convertDerToPem($der);

src/Library/KeyManagement/X5UFactory.php

@@ -30,7 +30,8 @@ public function loadFromUrl(string $url, array $header = []): JWKSet
 
         $keys = [];
         foreach ($data as $kid => $cert) {
-            if (mb_strpos((string) $cert, '-----BEGIN CERTIFICATE-----') === false) {
+            assert(is_string($cert), 'Invalid content.');
+            if (mb_strpos($cert, '-----BEGIN CERTIFICATE-----') === false) {
                 $cert = '-----BEGIN CERTIFICATE-----' . "\n" . $cert . "\n" . '-----END CERTIFICATE-----';
             }
             $jwk = KeyConverter::loadKeyFromCertificate($cert);