MainClass.java Source code

Introduction

Here is the source code for MainClass.java

Source

import java.io.FileInputStream;
import java.io.ObjectInputStream;
import java.security.MessageDigest;

public class MainClass {
    public static void main(String args[]) throws Exception {
        FileInputStream fis = new FileInputStream("test");
        ObjectInputStream ois = new ObjectInputStream(fis);
        Object o = ois.readObject();
        if (!(o instanceof String)) {
            System.out.println("Unexpected data in file");
            System.exit(-1);
        }
        String data = (String) o;
        System.out.println("Got message " + data);
        o = ois.readObject();
        if (!(o instanceof byte[])) {
            System.out.println("Unexpected data in file");
            System.exit(-1);
        }
        byte origDigest[] = (byte[]) o;
        MessageDigest md = MessageDigest.getInstance("SHA");
        md.update(data.getBytes());
        if (MessageDigest.isEqual(md.digest(), origDigest))
            System.out.println("Message is valid");
        else
            System.out.println("Message was corrupted");
    }
}