public static PrivateKey getSenderPrivateKey() {
        try {
            HDImageStore.setDir("/path_to_file/te-69214.000");
            KeyStore hdImageStore = KeyStore.getInstance("HDImageStore");
            hdImageStore.load(null, "password".toCharArray());
            Enumeration<String> aliases = hdImageStore.aliases();
            while (aliases.hasMoreElements()) {
                System.out.println(aliases.nextElement());
            }
            PrivateKey privateKey = (PrivateKey) hdImageStore.getKey("alias", "password".toCharArray());// privateKey is null
            return null;
        } catch (Exception e) {
            throw new RuntimeException(e);
        }
    }