java 代码内容如下（客户端要生成bin文件才能交互）求问 public.bin 文件如何生成的

public static void main(String[] args) throws Exception {
CertHelper help = CertHelper.getHttpCert();
Cert cert = new Cert("ticket", "8000", "http://127.0.0.1:8080/service/rbc.svc", "E:\key\8000\public.bin", "gbk");
help.putCert(cert);

    Cert tcert = help.getCert("ticket");
    System.out.println(tcert.getSignKey());
}

Cert cert = new Cert(....,...,....,..,..)加载文件 （E:\key\8000\public.bin）

public void loadCert(String fileName) throws Exception {
    File file = new File(fileName);
    byte[] b = new byte[(int) file.length()];
    FileInputStream fis = new FileInputStream(file);
    fis.read(b);
    fis.close();

    ByteArrayInputStream bis = new ByteArrayInputStream(b);
    DataInputStream din = new DataInputStream(bis);

    int len = din.readInt();
    keyBytes = new byte[len];
    din.read(keyBytes);

    len = din.readInt();
    modules = new byte[len];
    din.read(modules);

    len = din.readInt();
    byte[] ben = new byte[len];
    din.read(ben);

    BigInteger message = new BigInteger(ben);
    setSignKey(new String(message.modPow(new BigInteger(keyBytes), new BigInteger(modules)).toByteArray()));
}