public static KeyPair loadKey(File f, String passwd) throws IOException, GeneralSecurityException {
        return loadKey(readPemFile(f), passwd);
    }
@Test
    public void loadBlankKey() throws IOException, GeneralSecurityException {
        File file = new File(this.getClass().getResource("blank").getFile());
        String password = "password";
        assertThrows(InvalidKeyException.class, () -> PrivateKeyProvider.loadKey(file, password));
    }