Java自检程序(self-checksuming)

Question

我必须做一点 java 自检程序(self-checksum)。这是我的代码示例

public class tamper {
      public static int checksum_self () throws Exception {
          File file = new File ("tamper.class");
          FileInputStream fr = new FileInputStream (file);
          int result;                   // Compute the checksum
          return result;
      }
      public static boolean check1_for_tampering () throws Exception {
            return checksum_self () != 0; // TO BE UPDATED!
      }
      public static int check2_for_tampering () throws Exception {
            return checksum_self ();
      }
      public static void main (String args[]) throws Exception {
          if (check1_for_tampering ()) {
            System.exit (-1);
          }
          float celsius = Integer.parseInt (args[0]);
          float fahrenheit = 9 * celsius / 5 + 32;
          System.out.println (celsius + "C = " + fahrenheit + "F");
      }
}

我试过做类似的事情

DigestInputStream sha = new DigestInputStream(fr, MessageDigest.getInstance("SHA"));
byte[] digest = sha.getMessageDigest();

for(..)
{
result = result + digest[i]
}

但是我真的不知道如何检查？？

编辑:

感谢您的回答

@Adam Paynter 和 SpoonBenders

当然这不是我个人使用的。我不会用它来保护任何软件......

这是我必须为我的 Java 类(class)做的“练习”...

Answer 1

也许你应该看看signed jar files .