Jose\KeyConverter\KeyConverter::loadFromX5C PHP Method

    public static function loadFromX5C(array $x5c)
    {
        $certificate = null;
        $last_issuer = null;
        $last_subject = null;
        foreach ($x5c as $cert) {
            $current_cert = '-----BEGIN CERTIFICATE-----' . PHP_EOL . $cert . PHP_EOL . '-----END CERTIFICATE-----';
            $x509 = openssl_x509_read($current_cert);
            if (false === $x509) {
                $last_issuer = null;
                $last_subject = null;
                break;
            }
            $parsed = openssl_x509_parse($x509);
            openssl_x509_free($x509);
            if (false === $parsed) {
                $last_issuer = null;
                $last_subject = null;
                break;
            }
            if (null === $last_subject) {
                $last_subject = $parsed['subject'];
                $last_issuer = $parsed['issuer'];
                $certificate = $current_cert;
            } else {
                if (json_encode($last_issuer) === json_encode($parsed['subject'])) {
                    $last_subject = $parsed['subject'];
                    $last_issuer = $parsed['issuer'];
                } else {
                    $last_issuer = null;
                    $last_subject = null;
                    break;
                }
            }
        }
        Assertion::false(null === $last_issuer || json_encode($last_issuer) !== json_encode($last_subject), 'Invalid certificate chain.');
        return self::loadKeyFromCertificate($certificate);
    }

 /**
  * {@inheritdoc}
  */
 public static function createFromX5C(array $x5c, array $additional_values = [])
 {
     $values = KeyConverter::loadFromX5C($x5c);
     $values = array_merge($values, $additional_values);
     return new JWK($values);
 }