}

        String normalised = normaliseKeyId(keyId);
        try {
            return Long.parseLong(normalised, 16);
        } catch (NumberFormatException e) {
            throw new IllegalArgumentException("the key id \'" + keyId + "\' is not a valid hex string");
        }
    }

    private static String normaliseKeyId(String keyId) {
        String keyIdUpped = keyId.toUpperCase(Locale.ROOT);