/**
   @version 1.00 1997-09-10
   @author Cay Horstmann
*/

import java.security.*;

/**
   This program demonstrates how to sign a message with a
   private DSA key and verify it with the matching public key.
*/
public class SignatureTest
{  
   public static void main(String[] args)
   {  
      try
      {  
         KeyPairGenerator keygen
            = KeyPairGenerator.getInstance("DSA");
         SecureRandom secrand = new SecureRandom();
         keygen.initialize(512, secrand);

         KeyPair keys1 = keygen.generateKeyPair();
         PublicKey pubkey1 = keys1.getPublic();
         PrivateKey privkey1 = keys1.getPrivate();

         KeyPair keys2 = keygen.generateKeyPair();
         PublicKey pubkey2 = keys2.getPublic();
         PrivateKey privkey2 = keys2.getPrivate();

         Signature signalg = Signature.getInstance("DSA");
         signalg.initSign(privkey1);
         String message
            = "Pay authors a bonus of $20,000.";
         signalg.update(message.getBytes());
         byte[] signature = signalg.sign();
  
         Signature verifyalg = Signature.getInstance("DSA");
         verifyalg.initVerify(pubkey1);
         verifyalg.update(message.getBytes());
         if (!verifyalg.verify(signature))
            System.out.print("not ");
         System.out.println("signed with private key 1");

         verifyalg.initVerify(pubkey2);
         verifyalg.update(message.getBytes());
         if (!verifyalg.verify(signature))
            System.out.print("not ");
         System.out.println("signed with private key 2");
      }
      catch(Exception e)
      {  
         e.printStackTrace();
      }
   }
}